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User manual - Dewetron America

1. hui Y a i gt EN i S if A r E Y Y F rd Lee SIRENA E IA PS A A cee TE iy ke A E E Le i A i M i F 8 Ed get ee E e af ur a i i i naa e en ms a l l l i l l l j l l l I AA A A eee on 116 23 3 34 9 d5 5 Picture 6 TYPICAL FFT SCREEN Result of FFT is a set of amplitudes of certain frequencies Number of lines in the set is user selectable but they only change the resolution of the FFT Line resolution is a change in frequency between two frequency lines which are extracted from the signal and is calculated with equation SampleRate 2 3 LineResolution PC t NumberOfLines DeweFRF v6 5 Reference Guide v1 2 0 page 161 O 2007 DEWESOft Theory of single channel frequency analysis Properties of the Fourier transform So the question is why not always use maximum number of available frequency lines which gives more exact results The answer is simple because with larger frequency lines it takes more time to calculate FFT NumberOfLines 2 SampleRate 4 TimeToCalculate Just for fun we can also combine the equations above and we get 1 LineResolution TimeToCalculate Let s look to the equations above and make a list for 22 kHz sample rate Mumber of lines Line resolution Calculation time 512 21 5 Hz 0 046 s 1024
2. Export Fila Imoort N Guster To export save existing modified or new Measurement setup Ch setup i gf Measurement setup ee E Modal FRF data Export menu Measurement setup DeweFRF v6 5 User Guide v1 2 0 page 48 2007 DEWESoft Data management Measure setup file The standard Save As window is displayed for saving new or modified Measurement setup to dss file Save As My Recent Documents My Documents I ms My Computer a Mois mreza DeweFRF v6 5 User Guide v1 2 0 2007 DEWESOft page 49 Data management Geometry 2 3 Geometry We can define Geometry of mechanical structure for FRF testing in unv Universal file format data file as gt New project 2 Open project A Save project Mew geometry ME Save project as New geometry To define new geometry of mechanical structure for FRF testing choose File menu New Geometry Point Maker screen is displayed In this screen we can define geometry measured points of excitation and response and trace lines of mechanical structure A EEES Nodes TraceLines Auto scale Save Cancel A Geometry E Measurement setup Modal FRF Data y Otiects OWA Hode R Y E Delete all nodes Import geometry We can also load existing previous defined and saved geometry of mechanical structure from universal files into
3. Nodes FRF Setup Point Maker Node point has to be defined with an X Y and Z coordinate input in the Node table Each coordinate needs to have a value even the 0 value In order to enter a coordinate value the cell for the value must be left clicked and the value entered Coordinate value can be only a number The coordinate is chosen either by the Tab key or again by left clicking the cell If the X and Y coordinate are already defined as soon as the first number for the Z coordinate is entered a new coordinate line for a new node to be entered is displayed automatically The current node is enumerated Node column with a consecutive number If the entry of the Z coordinate is followed by pressing the Tab key then the cursors automatically goes to the X coordinate of the next node Of course to edit an existing node coordinate or to create a new node we can always left click on the appropriate cell For detailed description action with keyboard keys see gt Navigation keys First the Nodes has to be selected by clicking from the Point Maker menu There are three following basic procedures in Point Maker for nodes manipulation e New node e Edit node e Delete node Delete node Delete all nodes Save Cancel DeweFRF v6 5 User Guide v1 2 0 page 99 2007 DEWESoft Nodes FRF Setup Point Maker New node If the entry of the Z coordinate is followed by pressi
4. Back to Analog out channel list Back to Function Generator DeweFRF v6 5 User Guide v1 2 0 page 83 2007 DEWESoft FRF Channel Setup Channel setup Analog out The arbitrary waveform makes definition of special waveforms very easy through two tabs Signal tab Offset volts ees 10W ov Wy Phase degrees 3 oi OTO O T AF All parameters like Amplitude Offset and Phase can be set up as already known C hannel setup for channel 0 There are three ways to get a signal e The signal values can be entered directly in the table Points tab T Signal settings iarna a3 Signal Foiris ES Scaling Auto ro The waveform itself is defined in a table which can be displayed in the Points tab gt Signal settings Use this channel as signal output bd Waveform Arbitrary Signal Points Press or buttons to add or remove rows in the table and enter values for Time and Value amplitude e Paste from clipboard For example from Excel to DeweFRF If you copy from another programs like Word or other Editors be aware to use the tabulator as separator between the columns e Load from file The data have to be provided as standard text file txf with tabulator separated columns for time and amplitude values There is no header required DeweFRF v6 5 User Guide v1 2 0 2007 DEWESoft page 84 Channel setup FRF Channe
5. FRECUENCY SE TTIREIS Hel ut en ira dren chiro n t Prequency fy D On Min fragquenc Maciraquency erio m aisg 100 10 fioo Show ina channels AAA i TIME BETTINGS sex Startup lime Fall lime 0 Stop measurement after finish Joa fi wn Sane Tr 7 le ES Lite au en Seta pe J wo owo P Output channel maoe Im a ap Le setting vrs A Yo FT ME e tues eer o e LE IA TO NES A dl Available modes are fixed frequency sweep burst or stepped sweep There are many functions available for each mode like frequency operation mode timings control and so on For each channel individually we can decide on waveform type sine triangular rectangular saw white noise or trigger Amplitude offset and phase can be defined for each channel as well The start and stop of generation can be either on start of acquisition or manual Each operation mode carries different manual control atfixed frequency the generation can be started and stopped at burst mode the individual bursts are issued with manual control at stepped sweep we can go manual to the next frequency The start and stop of generation can be with a half sine window so the amplitude will not rise from 0 to full amplitude immediately but within a certain time which ensures that the systems under test don t suffer from impact shock If the shaker is used for excitation of structures single or multipl
6. Fa FAECAL WALES HERO ENE u et 3 ch zao ToO a seen F un A uM ze 3 Zero Zero 2500 Define and set all the channels which will be used during measurement A el 10 The basic channel setup is the same as in all Dewe software and can be read also in DEWESoft manuals Two tabs which is the most important for DeweFRF in the Ch Setup screens are e Analog tab define and set all the channels which will be used during measurement e Analog out tab gt define analog output setting Depending on selected choice in System menu Hardware setup we can set also other selected tabs eg Math etc DeweFRF v6 5 Tutorials v1 2 0 page 9 2007 DEWESoft Four step tutorial Channel Setup Analog channel setting 300 me 00k Maa a The important thing here is to choose and setup the channels which are used in the measurement with Slot input channel On Off activate deactivate channels C channel color selector Name channel name Amplifier amplifier type and ranges Physical values current input values Zero remove offset Setup input settings and calibration Channel naming There are two conventions how to name the channels that the point direction sign and point index will be automatically deciphered from the name You can use e 10x convention as the channel name where at first the number of point index is defined 10 in our case the
7. File menu gt Save project by New project by Open existent project By new project Standard Save As window is displayed see Warning existing project is saved without warning under same Save project as below project name and overwrite its data DeweFRF v6 5 Tutorials v1 2 0 page 38 2007 DEWESoft Project management tutorial Project file Save project as UG Hew project New geometry g Coen project QU Save project M Save project ase We can save the existing modified Project Channel setup data under a new name by selecting File menu Save project as Standard Save As windowis displayed for save Project data to dfs Dewesoft FRF project data file For detailed information see User Guide gt Import Export 4 2 Measurement setup file In Measurement setup file Channel setup data are stored Import ARa Measurement setup TE Modal FRF Data We can also directly Import Load Measurement setup data from ss Dewesoft setup file or Dewesoft text setup data file by selecting Import menu gt Measurement setup Export Ed Hodal PRF data We can Export Save existing modified or new Measurement setup data by selecting Export menu gt Measurement setup For detailed information see User Guide gt Import Export DeweFRF v6 5 Tutorials v1 2 0 page 39 O 2007 DEWESoft Project management tutorial Geometry
8. Time selector end date and time start date and time of stored data of stored data E WPA 1 11 Aa i Display stored data by channels For detailed information see User Guide gt Offline calculation DeweFRF v6 5 Tutorials v1 2 0 2007 page 21 DEWESoft Calculation tutorial Channel setup Frequency span By OFFLINE CALCULATION From stored data we can t choose or set the frequency span because it is defined by the sampling rate of time domain data which is loaded The FRF setup can be selected by clicking the FRF setup tool button First it is recommended to load or define the geometry see Import Export Geometry In our test example the geometry can be loaded with Import menu gt Geometry and loading EimerGeo unv for explanation click on field of interest Deer KF oes ES FRF setup toolbar Qe geport beet Ey for add and remove de E excitations responses iee FEF ep Mu E TRANSFER FUNCT ION SELECTOR Channels assignation and changing Point index of Excitation and Response channels Define GEQMETRY of shape basis for animation in FREs Analyse DeweFRF v6 5 Tutorials v1 2 0 page 22 2007 DEWESoft oo Calculation tutorial FRF setup The geometry in above screen describes the demo structure as seen below FRF properties Are the same as with measurement see gt Four step tutorial FRF S
9. e Excitation window length e Trigger level Few common settings are set regardless of excitation type e Frequency span e Averaging mode e Number of lines e Stop conditions e Calculation method e User defined OVL range Frequency span The frequency span defines the upper limit for calculation and the number of lines defines on how many segments this frequency span will be split In the example above Hi FFF setup the 500 Hz span is split in 200 lines resulting in 2 5 Hz frequency resolution The maximum sample rate allowable will vary according to which A D board you have installed and how many channels are activated for recording In the drop down list choose appropriate frequency span Note The sampling rate is set to 2 1 28 Frequency span The factor 2 is the Nyquist factor for sampling and 1 28 is used to assure that the results will be alias free So if the frequency span is 2000 Hz the sampling rate will be set to 5120 Hz DeweFRF v6 5 User Guide v1 2 0 page 87 2007 DEWESoft FRF Setup Common FRF property panel setting 2000 UU verage mode Average Count Linear Number of lines Number of lines combined with frequency span defines the resolution of FRF The span frequency is equally divided in number of lines If we have 200 lines and the frequency span is 2000 the line resolution will be 2000 200 10 Hz Calculation method There are three calculati
10. e SPEED BEZE Z scare When triangle button is pressed shapes deflections size increase for 0 1x When triangle button is pressed shapes deflections size decrease for 0 1x SCALE 1x o SCALE 0 5x see bo SPEED When triangle button is pressed shapes deflection animations speed increase by step of 1Hz when triangle button is pressed shapes deflection animations speed decrease by step of 1Hz DeweFRF v6 5 User Guide v1 2 0 page 125 O 2007 DEWESOft o Analyse Analysis tools 6 4 Analysis tools If the geometry has been created or loaded the deflection shapes can be observed with animating the points on the structure or showing the maximum deflection shapes This actions will be taken by buttons on main Analysis too bar ren To clipboard LEE F a Export FRFs data Tools for List of Measured FRFs Analysis tools Analyses tool bar is divided in three parts Info of complete FREs Measure 1 On left are tools for List of Measured FRFs see Delete FRF from list 2 Right most is Info tool for complete information of FRFs see Info 3 On right side are tools for manipulating FRF data see Export FRF data 4 On central part of toolbar are real Analyse tools e Animate e Max shape e Circle fit Note Whena SISO single input single output model is used we have on toolbar additional button x pa MES AG oy lp Delete Demisal Flemeasue Animale M
11. 10 mVAbf 2 25 MWIN for sti Measurement Range 500 Ibf pk 2200 N pk T Frequency Range 10 dB Hard Tip kHz 2008 HZ 112 EE Frequency Range 10 dB Medium Tip 2 5 kHz 2500 Hz fz Frequency Range 10 dB Soft Tip 750 Hz 750 Hz 1112 Not Frequency Range 10 dB Super Soft 600 Hz 600 Hz 2 1112 Tip i Resonant Frequency 222 kHz 222 kHz The important field in the calibration sheet is sensitivity In our example the modal hammer has 2 25 mV N sensitivity This means that if we hit with 1 N force it will produce 2 25 mV at the output DeweFRF v6 5 Tutorials v1 2 0 page 27 2007 DEWESoft SISO Single I O modal analysis tutorial Channel setup To scale the excitation channel we first need to enter the measurement units Since we measure the force in newtons we enter N as the measurement unit Immediately this unit will be shown in the scaled value preview of the channel setup Next we have to enter the sensitivity We go to Scale by function tab and choose the sensitivity radio button instead of scaling In the entry field we need to enter sensitivity in V N Since we have the sensitivity defined in mV N we need to convert it to VIN In our case 2 25 mV N 2 25 1000 V N 0 00225mV N We immediately see on the right side what is our scaled measurement range In our example the maximum range is 2222 N This means if we hit with more than this force the channels will overload and the measurement will
12. AS lol i ds As The cell for the node input is selected using the left click During the entry of the node the cell for the next node is created below Nodes 1 Tracelines Objects TracelLmes Trace ines 1 Trace line 1 il The cell for the node input is selected using the left click During the entry of the node the cell for the next node is created below Modes i Tracelines Objects TraceLines Trace line 2 Trace ine 1 Trace ine 2 DeweFRF v6 5 User Guide v1 2 0 2007 DEWESoft page 103 Trace Lines FRF Setup Point Maker The next cell of the node list is selected using the Tab key or left clicking At the same time the trace line is displayed in the Geometry window al 3 E Can El nr Ta ore Nodes TraceLnes Objects e a Fi Pr TraceLines Trace line 2 Trace ine 1 3 Trace ine 2 4 Delete all tracelines Auto scale Save Cancel Point Maker O xi Nodes 1 TraceLines Objects ES ES Tracelines Tracelme 1 Tracelne 1 1 ssl w al ms Delete all racelnes Auto scale Save Cancel Edit trace line Name Node Using the left click we select the cell with the trace line to be changed Using the left click we select the cell with the node marking to be at the same time the header for the right column is being modified changed de Obie TraceLines Trace Line 1 Nodes Tracelines Objects Trace eve 1 1 Trac
13. DeweFRF v6 5 modal analysis software User manual v1 2 0 2007 DEWESOft General information Software version DeweFRF User manual corresponds with software version 6 5 Printing notice Specifications subject to change without notice Copyright notice 2007 DEWETRON elektronische Messgeraete Ges m b H All rights reserved May not beduplicated or disseminated in any fashion without the express written permission of DEWETRON Ges m b H Trademark notice All trademarks are acknowledged to be the property of their owners with all rights and privileges thereto Noinfringement is intended Microsoft Excel and Word are registered trademarks of Microsoft Corporation National Instruments is a trademark of National Instruments Microstar DAP and DSC are trademarks of Microstar Labs Inc Data Translation is a trademark of Data Translation Inc Disclaimer DEWETRON makes no claim about the efficacy or accuracy of the information contained herein Use ofthis manual is entirely at the user s own risk Under no circumstances will DEWETRON assume any liabilitycaused by the use proper or improper of this manual or the information textual graphical or otherwise contained within it DeweFRF 6 5 User manual v1 2 0 Contents Table of Contents Part Welcome to DeweFRF Getting helo j Mana Basis of work with DeweFRF _ C_ C nue nuuuauuuuuuuuuauueuuuanuaueeauees System requirements gt
14. Reference Guide v1 2 0 page 170 2007 DEWESOft Theory of single channel frequency analysis Representation of different signals in the FFT resolution time signal should show at least 16 or 32 modulation peaks that the modulation is shown in the FFT mall o a 01 0 2 03 s Sd a 31 100 110 120 Picture 29 TIME DOMAIN AM SIGNAL Picture 30 FREQUENCY DOMAIN AM SIGNAL 2 8 Conclusion There s no doubt about it FFT is a powerful analysis But it is just like a car If we know its limits we can get so much more performance from it That s why it is important to know how it is calculated and the tricks that might come handy The next step in one channel FFT analysis is the real signal analysis which comes from the knowledge of the measurement If it s machine vibration we have to know the structure and the properties of mechanical elements and structures If it is an electronic circuit we have to know the properties of electronic components to figure out the responses With this step the FFT analysis steps out of being a mathematical principle and becomes just a handy tool like it really should be DeweFRF v6 5 Reference Guide v1 2 0 page 1 1 2007 DEWESoft H1 H2 and HV algorithms for calculation 3 Hi H2 and HV algorithms for calculation H1 algorithm H1 algorithm expects noise on output H1 algorithm tends to minimize the noise on output In the presence of noise it underestimates am
15. Units Color Min value Automatic Mas value ETES Sample rate divider For explanation click on field of interest MDAG ACC 5N 239400 Rev 110 Range 10000 m Input type 4 ICP Voltage Current f dm Em current is valid for MDAQ ACC channels 0 7 Coupling DC f AC I3 Hz MD40 Baze SN 111111 Rex 103 DeweFRF v6 5 User Guide v1 2 0 2007 DEWESOft et Channel Setup FRF Channel Setup Analog Measurement value and unit Measurement value can be F or Force Load etc and are entered as text Unit of measurement value N newton kg V etc are entered as text Navigation keys are same as in other Windows application Min Max value The Min value and Max value fields represent a definable standard display range e as a Standard DEWESOoft displays the whole input range of the channel in each display eg the recorder This fields is set to Automatic e If you now have a wide input range but your signal is small you can define this field as narrow standard display range You can enter range as usual number navigation keys are same as in other Windows application Enter key also closes Channel setup window To set the values back to Automatic range detection just right click in the desired field and select Set to Automatic from the list Min value tom Set to Automatic i LE EY 2 This function is used only to define the standard range values for the display it ha
16. Blackmann or Kaiser window is better choice because sidebands are 10 times lower than with the Hanning window However the sideband width is wider Here it comes to the point if more lines in FFT are chosen we can use these windows and still larger sidebands have no real disadvantage If correct amplitudes are searched we should use the flat top window The amplitudes would be wrong by only a fraction as low as 1 Of course there is a penalty neighbor frequencies are also very high sideband width is high This window is most suitable for calibration But here it is the same with modern equipment with lots of lines this is no longer that much of a problem Picture 16 HANNING WINDOW Picture 17 FLAT TOP WINDOW Window characteristics maximum amplitude error sideband width highest sideband attenuation sideband slope attenuation are best described on picture 18 We have already discussed about maximum amplitude error it is an error of amplitude if sine waves does not fall on frequency line Windows try to eliminate this problem and because of that they widen the first band The sine waves are not longer one line in FFT but spread along several lines Ability to recognize small sine waves among larger ones is determined by highest sideband attenuation and sideband slope attenuation These two values determine the leakage of the FFT and that s nicely seen on picture 18 If for example there would be a frequency of 30 Hz with amplitu
17. Re Sn Channa Excitation The lower transfer function list is the selector which transfer function pean le RET or channel is shown on selected graph but also provides the information about the amplitudes of each input and output In case of overload the bar below the channel names turns out in red If the overload is gone the bar turns back to green but still it shows the red border around the channel indicating that the channel was overloaded once during the measurement 9 1 Graph Display Central part of Measure screen displays graphs We can e select channels which are displayed e set display properties of particular graph The mouse moved over the graph will show cursor values for nearest point and if we click on this point the amplitude and frequency will remain shown DeweFRF v6 5 User Guide v1 2 0 page 113 2007 DEWESoft Measure Graph Display The Excrabon scope OU 1 40 Reside cope l TE T AE ka A MA A Il IA A Ta AN il ai m N l n y a A Mit AT JA A Hi A ph ps Angle de q Ex OE Transtar curma gra yo z consists of the displays e Excitation scope e Response scope i m rt q 4 e Excitation FFT current and averaged DeweFRF v6 5 User Guide v1 2 0 page 114 2007 DEWESoft Measure Graph Display e Frequency response function Selection of channels To select channels or properties for each
18. Reference Guide v1 2 0 page 164 2007 DEWESoft Theory of single channel frequency analysis Where we can get in trouble To really see that effect it is the best if function generator and simple A D card is used and the online FFT analyzer perfectly shows the problem Since this is not possible in the written article we will use waterfall diagrams to see the problem Both pictures 13 and 14 show the sine sweep from zero to 1 5 kHz On picture 13 the signal is sampled with 1 kHz and on picture 14 the signal is sampled with 10 kHz On picture 14 we see right result but on the left we can clearly see that the signal above 500 Hz bounces back zero and then over 1 kHz is starts to rise again but the truth is all that frequencies are not correct 141 1i i FF i a AIN IL I Hi di 0 1 A LU A Me E O 150 ia x ano Picture 13 ALIASING IN THE FFT Picture 14 CORRECTLY SAMPLED SIGNAL 2 5 How can we at least try to avoid it For the problem of aliasing there is not much to do in the FFT domain Actually there is absolutely nothing we can do when the samples are already taken So the first way would be to choose the A D board who has anti aliasing filters in front the second way would be to use external filters or we can simply set the sampling rate to more than twice the maximum frequency present in the signal according to equation 2 For amplitude errors a bunch of people tried to minimize that
19. iT i A MA AE h Now you can enter the Shown time and the exact Start show time position within the file This is first way to narrow range of displayed data and later recalculating only these DeweFRF v6 5 User Guide v1 2 0 page 135 2007 DEWESoft Time overview bar Offline calculation Channel setup By defining Time selector of measurement define Show and Start show Time we can select only part of the time scale smaller range of stored data In example bellow we set Show time on 2 sec and Start show Time we increase for 14 sec from initial start time of stored data xl eO Ee H 2 S60 E Cancel IE 102005 fi4 4715 468 and we get screen like below 10 x Ple mport Export System Line J a Ch setup FRF setup Calouiste naise From measure Fil name FF From stored date Fe par Den Per DENE RSR hep Dira PREDIO IRIQGOR POE lt ei E The result depends on the used screen For DeweFRF offline calculation multiple value element like the recorder scope FFT are predefined and that will display the signal only within the selected time window like a zoom function We can see the time scale on the bottom of Display of stored data include only selected range of stored data in our example from 14 00 sec 16 00 sec i e entered Shown time 2 00 sec 2 Time overview box Selected range of stored data within the whole signal is marked in the Time
20. l a e hn AF sea hisa far Fin sure Fa mama Pr E 1 4 ET Eco sica dal en E DEN Function generator setting alri Ay ag oul Fes Sweep Step sweep Burst E Chip Start output on statacg FREGO ENY a ERREURS iman char ifs ASN Frequency es ri Min Maxx fraquar fo fro E Show into channels M Stop measurement after finish lelelelsislele lt Output channel setting Columns in the channel list explained First let s look at the columns that are shown in your analog out channel list and describe what each is for Slot Output channel On Off activate deactivate channels C channel color selector Name channel name Value amplifier type and ranges Setup channel settings DeweFRF v6 5 User Guide v1 2 0 page 73 2007 DEWESoft Function Generator FRF Channel Setup Analog out DewerFRF software offers a full featured signal generator with 16 or more analog signal outputs any analog output card from National instrument can be used as the hardware with different e operation modes e signals Waveform Analog output channels which will be used during measurement are set in Ch setup on Analog out tab Mai JE x ive tbe otis h he FAF isiu Has pos FF Fie name Faq 5000 EDEN A ee Foon ee Function generator setting malog Analog qu Fed Sweep Stepsweep Burst Chip Slant output on sat acg
21. o cmsncnrnnnnnnnannnanacnnanancnna anna Part Il Tutorials Four step tutorial ccmcinnnnnnnnnccinini nana nanan anna Channel Set p amina oda FRF Sep ais Measure o dieser A alyse id Calculation tutorial Channel Setup aiii ad PRESCLUD a AA Analyse inserer mimi pue SISO Single I O modal analysis tutorial cocococccoccccnonnnonnnoo Channel Setup amaia A A ni ee nnneninnns Measure a AN AIYSE Zaire tee Project management tutorial Project lle NN LL aia 2007 DEWESOft DeweFRF 6 5 User manual v1 2 0 Contents Il MeGEaSUFEMENLSELUD file UN den M A a eine 39 Seometiy a a ed das 40 MOdaERFDatatlle A SA 41 Part lll User Guide 43 Measure methods nanas nr cnn nora nnnrnrnrnananararnrnanananannrnenananas 44 Data management air 45 PROC a 46 MeEaSUreSGIUD ING ii A M A en 48 A aia a aE A aah wicasceesixvecsaviwevsvessniasecssinbens 50 MOdal FRF OR Nidos 52 Time data Subs EA 54 FRF Channel Setup aaa 56 A ADE O A ca 57 InNPUtecnhanmel SION SN li 58 Activating NPSA OO ne ne cr cc ee 59 CRAN OR Hunan eu 60 Channel name Name idee eueencencencenceecneeneeeeneeneenese 60 AMPUH T IVPDE ANA andes seanina a a a 61 PAYSICAL vales noia dao 62 WAU ZEROING Zero ER dc 62 Ai O A o PAP amet conetaweuenaceutauieaaa eg eancamened 64 A ne fs Dieu A et 64 Scaling iar ala le Le en Ra de
22. 4 3 Geometry You can define the Geometry of mechanical structure for FRF testing as New Geometry Import Geometry G Hew project Ge Open project E save project Save projet a we can define New Geometry by selecting toload existing previous defined and saved geometry of mechanical structure from universal files into Point Maker screen select File menu New Geometry Import menu Geometry and Point Maker screen in Ch setup tool is displayed for define new geometry Export Geometry After defining new or modified existent we can Export Save Geometry by selecting Export menu Geometry Standard Save As window is displayed for save new or modified Geometry to nv Universal file format data file WARNING because Geometry and Modal FRF Data is stored in same unv Universal format file it is strongly recommended to use separate filename for new or modified Geometry For detailed information see User Guide gt Import Export DeweFRF v6 5 Tutorials v1 2 0 page 40 2007 DEWESoft Project management tutorial Modal FRF Data file 4 4 Modal FRF Data file In Modal FRF data measured data are stored toload existing previous saved measured data from unv Universal file format data file into Analyse screen select Import menu gt Modal FRF Data In both case Save FRF data As window is displayed for saving new or modified measured data to nv U
23. Analyse Analysis tools 6 4 3 Circle fit For a quick and simple validation of results circle fit is provided for calculation e of exact frequency of mode and e damping of the structure It has to be noted that circle fit is single degree of freedom fit so it calculates the results only for a single mode and gives good results only if modes are well separated 10 x IR BA H H A AD En az y CH np FRF setup Calcule Area Delete Dalsia al Arenas Higos ges Circle it Tocipbowd UFF expert Prey Regis l Pet pet ms Bey Se Sa e Ele pe ep ea ea pe ope pa pa ped ee gt Fe oe h A A ia H tu Fes 179 12 Smua asma 00079643 DeweFRF v6 5 User Guide v1 2 0 page 130 2007 DEWESoft Circle fit Analyse Analysis tools Cet When circle fit is selected the FRF list is expanded with Circle fit selected error channels panel to show us e maximum amplitude and Natural freq 933 28 Struct damping 0 024309 e phase of the certain FRF point The amplitude and phase is calculated from the mode circle as the highest value Below the number of Fit points can be chosen Number of fit point tells the width of the calculation we have to be careful not to choose too high number otherwise neighbor modes might affect the results This number has to be a maximum value that the points still lay on the circle In order to help to define
24. DeweFRF v6 5 Reference Guide v1 2 0 page 162 2007 DEWESoft Theory of single channel frequency analysis Properties of the Fourier transform os E Da D Picture 9 LINEAR FREQUENCY SCALE Picture 10 LOGARITMIC FREQUENCY SCALE X scale can be either linear or logarithmic Linear scaling is the correct representation of the mathematic transformation and usually gives best information for analysis Sometimes like in the example shown in picture 9 it is nice to see x axis in logarithmic values since most interesting frequencies are in a lower region We have to know that just to set the x scale to logarithmic does not enhance the results in the lower region so the resolution will be better in the upper region since there are more frequency lines available there If we use another technique called CPB for constant percentage bandwidth or octave analysis this will give us same resolution in all regions when x axis is logarithmic This is achieved by the fact that upper region lines covers wider frequency ranges than the lower one The resolution of the bands is defined by 1 n description where n is the number of bands in one octave Most widely used is 1 3 octave analysis which is the standard for noise measurements 1 12 and even better 1 24 octave analysis already gives good resolution also for signal analysis 2 4 Where we can get in trouble Because there should be at least one equation in each chapter lets use the
25. In our case the frequency resolution will be 2000 Hz 400lines 5 Hz DeweFRF v6 5 Tutorials v1 2 0 page 30 2007 DEWESoft SISO Single I O modal analysis tutorial FRF setup File Import Export System re EA am A 5 Ch saup FAP setup Mentir ak Add Fist Acid Fl mirus PRICE Shame Padiri Response Por incas Fie run tevin agi Lines Ash ET Then we define the Trigger level in N Since the structure is very light we need to excite it with a low force to prevent double hits Few newtons of force is suitable In general the heavier is the structure more force is needed to excite it With very large structures and complex structures the SISO method is not suitable and we have to look for more sophisticated methods to excite the structure with one or several shakers Next we define the Pretrigger Few percent of pretrigger is nice to get also the whole rise time of hit even before the trigger level is achieved We can also define the number of hits for one measurement point In our case we have chosen to put the sensor on the bottom of the beam on point 2 The reason for this is that we need to measure mobility point Mobility point is the point where the excitation and response is the same If this point is not measured we can t calculate excitation response matrix in full we need this for animation and modal parameters calculation T
26. Input and Scaled signal are represented on dynamic graph DeweFRF v6 5 User Guide v1 2 0 page 71 2007 DEWESoft Channel Setup FRF Channel Setup Analog If you have an AC signal source you should also press the Input value Scaled value AC RMS 10000 mY 200 N button below the graph to add the RMS 6956 2 mV 139 124 N values to the dynamic display 4701 3 mv 35 627 N 109 8 mv 2 196 N When 6696 2 mV 133 923 Average Min Max AC RMS la oh buttons are pressed Average and Minimum Maximum and Average ACRMS Min Max AC RMS values of your Input and Scaled signal are represented on dynamic graph Back to Channel setup Scaling Back to Analog channel list page 72 DeweFRF v6 5 User Guide v1 2 0 2007 DEWESOft FRF Channel Setup Analog out 3 2 Analog out DEWESoft offers a full featured signal function generator with 16 or more analog signal outputs as an option One of the available tabs In Ch setup screen next to Analog and eventual others eg Math has to be labeled Analog out In this tab in the upper part there are the definitions of a Function generator and at bottom part table the Channel list in which we can set all the analog out channels which will be used during measurement The handling of this settings is already well known from the Analog input section and very similar for explanation click on area column of interest 10
27. Measurement setup 48 REAL PROF mode 154 Modal FRF data 52 Project data 46 Analog IN channels list setup Time data 54 Amplifier column type and ranges 61 Channel color C column 60 DEMO mode 153 Channel name Name column 60 DeweFRF System setting 150 Channel Setup setup column 57 58 60 61 62 General setting 150 Input channel Slot column 58 Hardware setup 150 Input zeroing Zero column 62 Physical values column 62 E Analog OUT channels list setup 73 Activating outputs On Off column 79 Export 45 Channel setup setup column 81 Geometry 51 Channel value value column 79 Measurement setup 48 Waveform type 80 Modal FRF data 52 Analog OUT channels setup 73 Channel list setup 73 y Function Generator 74 ana 00 FRF setup 86 n se FRF property panel 87 Analyse tools 126 Geometry 94 Animate tool 126 Point Maker 98 Circle fit tool 130 Transfer function selector 92 Export measured FRFs data 131 FRE graph 122 Function Generator 74 Geometry window 124 Control Options 78 Info tool 132 Operation modes 75 List of measured FRFs 121 2007 DEWESoft page 174 DeweFRF v6 5 User manual v1 2 0 Index Analyse 145 Calculate 143 G Channel setup 134 Geometry FRF setup 142 Analyse window 124 Import time data 54 FRF setup window 94 Selection range of data 135 Point Maker 98 Store time data 55 Open 45 Project 46 H H1 H2 and HV algorithms 172 P Hardware setup 150 Analog HW Device 151 Point maker 98 Analog out setup 157
28. ORIOMN 1624 fac 2 0 or higher E series AD boards 6 9 3 or higher NHAT and Ni4551 senes boards 6 9 3 or higher NI6602 series boards NI DAC 6 9 3 or higher M serios boards Sor hiaher ISA PCI and USB A D boards min latest recommended MI Sho MI Stoo Mi dx MI ho senes boards latest recommended Detailed information about the installation procedure is available in the drivers documentation In System Hardware setup Analog tab Dewetron modules you can activate DEWETRON DAQN DAQP MDAQ TEDS PAD EPAD modules for eee click on ADEN part of screen Analog CAN CAN GPS Video Math Timing Alam ar Analog EE PI mes Licensing Analog device f Dewetron m Dewetron DSA a 2 4 nse mi C Card FOUND I Use TEDS senos 7 Use DAQN modules Casein Giowina Dieaweinin TA hankaa Activate Dewetron DAQN modules To activate DAQN series modules support simply click on the Use DAQN modules checkbox This will enable a selection list of modules in the input setup Activate Dewetron DAQP MDAQ modules To activate DAQP series modules support in DEWE software click on the Use MDAQ DAQP modules checkbox and select the serial interface which is used for the communication in COM port DeweFRF v6 5 Reference Guide v1 2 0 page 152 2007 DEWESoft Analog HW Device DeweFRF System setting Hardware setup If you are using any DEWETRON hardware like a DEWE 5000 DEWE 3020 DEW
29. System gt Hardware setup gt Analog tab Analog device and activate DEWETRON modules in System gt Hardware setup gt Analog tab Dewetron modules Depending on the manufacturer the installed hardware offers different settings As an example you can set the National Instruments hardware to RSE referenced single ended standard with DEWETRON systems NRSE non referenced single ended or DIFF differential Card specification is displayed in button part of screen Device information DeweFRF v6 5 Reference Guide v1 2 0 page 155 2007 DEWESOft Analog HW Device Hardware setup A very nice and important feature for high channel count applications is the ability to group channels The grouping can be DeweFRF System setting done completely independent each group can have different number of channels and start at any channel number required Normally the systems will be set up with hardware like groups that means 16 channels per group Here is an example where grouping can be used the system includes two 32 channel A D boards 64 channels total Let s see how to set up 4 groups each with 16 channels PCl 625 1250k2 s T2850 ko res foo ME A A A A a a a in a ie Al resaltan Er PC 5 1361 F 16 El 1 Il r 1 To use the grouping for this system you have to click the grouping checkbox The Add Remove buttons will become active icon and activate the Enable AI
30. a new file name and store data under this name After pressing Store time data button on Ch setup and Yes on Warning screen we get screen like this DeweFRF y ES Ge PEA Se Ch setup FHF setup Mesure Arabia pedia File name Frea span ECOS e o eea eats C Deatao Progam DEWE Go E Npp DoF RF Dris Creating own display On this Online Overview Display screens window are predefined display of standard Digital meters for all used channels and Control properties for this type of display When you press the Design button you are allowed to create your own display Designing of displays is the same as in Dewesoft Please refer to Dewesoft user s manual for help on designing the displays DeweFRF v6 5 User Guide v1 2 0 page 55 2007 DEWESoft FRF Channel Setup 3 FRF Channel Setup Channel setup is the second step of four basic steps how to do a modal analysis Inthe FRF Channel setup we can define and set all the channels which will be used during measurement using applied hardware Channel setup is relevant to measuring see gt Measure methods directly while acquiring data with continuous or impulse or for offline calculation From stored data excitationin new or existent project Set all the channels which will be used during measurement Set Time selector Show and Start show Time in Analog and Analog out tab Store time data o About Channel setup for offline calculation see store
31. click on field of interest Back to Analog out channel list MDAQ ACC 5N 239400 Rev 110 Dynamic representation of signal to observe directly the effect of your calibration value Perform manual or automated calibration on a 2 point ora functional basis input value Scaled value 10000 m 200 N 7663 3 m 153 265 H 126 8 m 418 5 mv 10000 ay The bottom left corner of Channel setup screen is where you can perform scaling either on a 2 point or functional basis and manual automated calibration The bottom right portion of the dialog contains a dynamic representation of your signal the eft side are the electrical units and the right side is the scaled engineering units so you can directly see the effect of your calibration values Back to Analog tab Channel setup Back to Analog channel list DeweFRF v6 5 User Guide v1 2 0 page 66 2007 DEWESoft FRF Channel Setup Channel Setup Analog 3 1 8 2 1 by two points Scaling by two points by function First point Second point Calibrate from average from RHS Calibrate from average from RHS Innit value 7 m E EELIS A Li Po a rap rl to li a ee ee o 10000 mY 00 N 663 3 mY Ce 153 265 H 126 6 mY 2 536 H 7418 5 mY 148 370 H 10000 mY 200 H w 01 A sec Average AC RMS Hin Z Max Ok Cancel In this example
32. delete node 100 Licensing 158 editnode 100 Mathematic functions 157 navigation keys 101 newnode 100 R Import 45 Geometry 50 REAL PROF mode 154 Mesurement setup 48 Modal FRF data 52 S Save 45 M Project 47 Measure 112 Scaling in channel setup 66 Basics methods 44 by function 68 Graph display 113 by two points 67 Tools 119 dynamic graph 71 Measurement Setup dynamic representation 70 Ana Y Set frequency span 57 AnalogOut Tab 10 Setup of Analog IN channel 64 Channel Setup 10 General 64 Menu 146 Scaling 66 Setup of Analog OUT channel N Arbitrary Additional settings 84 General 81 New 45 Noise Additional settings 83 PEOMENY 5H Signal setting 81 Project 46 Signals out operation modes 75 Burst 77 O Chirp 77 Fixed 75 Offline calculation 133 page 175 2007 DEWESOft DeweFRF v6 5 User manual v1 2 0 Index Signals out operation modes 75 Step sweep 76 Sweep 76 SISO Single I O modal analysis 27 SISO Analyse 35 SISO Channel setup 27 SISO FRF setup 30 SISO Measure 33 System requirements 5 ef e Theory of single channel frequency analysis 159 Time data 45 Load time data 54 Store time data 55 Tutorials 7 Calculation tutorial 19 Four step tutorial 8 Project management tutorial 37 SISO Single I O modal analysis tutorial 27 W Waveform Additional settings 83 Arbitrary 83 Noise 83 2007 DEWESOft page 176
33. e WINDOWS 2000 XP 1 e Intel Pentium 4 2 4 GHZ processor or higher e 512 MB RAM or higher e Serial ATA or SCSI hard disks and or RAID systems e Approx 40 MB free hard disk space for DEWESoft Additional 20 to 200 MB for drivers and post processing software packages e A D board for using real mode requires licence key for setup this hardware see Hardware setup We strongly recommend to run DeweFRF with Windows Administration rights otherwise file access or driver problems might occur 1 DeweFRF is not running under WINDOWS 95 98 ME NT4 operating systems DeweFRF v6 5 Welcome to DeweFRF v1 2 0 page 5 2007 DEWESoft Part Tutorials 2007 DEWESoft DeweFRF v6 5 User manual v1 2 0 Welcome to the tutorials of DeweFRF modal analysis software In DeweFRF software TUTORIAL are four basic tutorials available explains basic steps to do online modal analysis in DeweFRF and is recommended for all new users explains the procedures to do modal analysis from stored data explains the specialities if the structure is excited with single input and measured with single output SISO will help to explain how to work with projects and how to import export measurement setups geometry and FRF modal data DeweFRF v6 5 Tutorials v1 2 0 2007 DEWESoft page Four step tutorial Four step tutorial This tutorial will guide through four basic steps how to do modal
34. first row upper parts of screen are different menus e In second row upper parts are icons with DeweFRFs basic tools Ch setup FRF setup for for e In main part are data of central softwares producer version and copyright for FRF data DeweFRF v6 5 User Guide v1 2 0 2007 DEWESoft page 146 DeweFRF software interface Menus File menu gt New project Open new project New geometry define new geometry Open project open load saved project Save project save project E Save project as save project under different name 1 beam open load last saved project I Il a exit Dewe FRF software g All choices displays standard Windows dialogs except New project open Analog tab for set all channels on Ch setup tool screen New geometry open FRF setup tool with separate window Point Marker to define new measured structure Import menu e eometry load existing previous defined and saved geometry of mechanical structure G Measurement setup Modal FRF Data import Measurement setup data from Dewesoft setup file or Dewesoft text setup load existing previous saved Modal FRF Data measured data from universal data file E Geometry save new or modified existent geometry of mechanical structure El Measurement setup Jl Modal FRF data ie Ch setup export existent modified or new Measurement setup data save Modal FRF Dat
35. fixed Startup time ts and a Fall time tf define the ramp slope at the beginning and the end of the function Analog Analog out Fixed Sweep LE sweep Burst Chirp Applications this mode is mainly used for modal structural tests Burst In burst mode Startup time ts Fall time tf and Hold time t1 can be defined Within the burst we can choose to have any signal but in practice noise is usually used as the base generated signal Within the startup and fall time you get noise output If the Cycles n checkbox is enabled it is possible to set the number of burst to output Analog Analog out Fixed Sweep k iiai sweep ES Le Chirp Applications Bursts are usually enhancements of the noise excitation for measuring transfer functions With the burst mode the need of using windows for frequency analysis and therefore errors caused by windowing is eliminated They are useful at testing response characteristics of the systems DeweFRF v6 5 User Guide v1 2 0 page 77 2007 DEWESoft O Function Generator FRF Channel Setup Analog out Chirp The chirp mode generates a signal which changes its frequency within a certain time It is similar to the sweep mode but in chirp mode the sweep time is shorter and the function is repeated after a defined time Start freq f1 and End freq f2 define the frequency range of the chirp The Frequency change can be either linear or logarithmic Additional
36. following one n gt 0 6 X jo gt X n e n gt 00 This is the theoretical discrete Fourier transformation and it has absolutely no error The only thing which could be bothering is the sum goes from minus infinity to plus infinity Because in the fast world we live in we don t have the time to wait that long we run in problems 1 Amplitude error picket fence effect The first problem is shown already in theory chapter The sum can produce not null results even if the signal does not correspond to the frequencies extracted from the signal The pure frequencies are because of that somehow leaked over neighbor frequencies For the same reason if the frequency does not exactly fall on frequency line amplitudes seem to be lower This is called picket fence effect Let s look at the picture 11 if a frequency is exactly on the spectrum line and some examples in between On the picture below 10 and 12 Hz are the exact frequency lines On the example there are 10 and 12 sine waves marked as black which are transformed correctly and there are frequencies in between which has lower amplitudes Maximum amplitude error can go up to 35 of the correct value DeweFRF v6 5 Reference Guide v1 2 0 page 163 2007 DEWESoft Theory of single channel frequency analysis Where we can get in trouble 1 0 8 0 5 NETA 0 7 0 8 RP EI Le Rs LE PSE RER 0 5 FETE A E 20 Picture 11 AMPLITUDE ER
37. graph E nd limit of B egin limit of stored data stored data E y 1 J I Start show time of range II End show time of range EL 1 al A 051 ME J 13 al k MP 1 j cursor 5 r i al P es it a h LA 1 k hi I F 4 iJ rl J ii Fi r 4 EA n di i h a i PT z ER 1 Ma A de del B fi pr A PL we et A EAI Le a Ve A EELT E oast Ma sh le Ty LL Mora core L I al i atts A mt teal b pi Aa AA ma de ik au kaf ii jai aa yi pv an y 1 a LE Y a r a aj ma E vit fa la j M3 ja z 5 j i at W H pe er 4 A hy h F Y Pp LE j i 1 i Cu j i i Wi ely Aa Boa A AN 1 i a P 7 bit ad J a 1 mP i i E On the left part of the display the readout values of the currently selected graph will be displayed To show values from another graph simply click on it and the values will change As there is only one time base available the cursor position is the same for all displayed graphs DeweFRF v6 5 User Guide v1 2 0 page 138 2007 DEWESoft Display of stored data Offline calculation Channel setup Selection range of stored data On Display of stored data we have another option to narrow range of displayed data and later recalculating only these and only part of time scale smaller range of stored data 1 Measurement cursor The recorder offer two measurement cursors for the active graph on top labeled with for Start show time and Il for En
38. infinite frequency spectrum of the white noise is the straight line However the shorter the samples are more different amplitudes for certain frequencies we get in the noise level It is the best to use averaging to get fixed noise line Picture 24 shows already averaged FFT of the white noise 0 0 2 DA 0 5 05 1 a 100 200 300 400 ts fa Picture 25 TIME DOMAIN NOISE Picture 26 FREQUENCY DOMAIN NOISE 4 Beating two closely spaced signals Beating in time domain is somehow hidden and looks like one frequency with changing amplitudes Only FFT reveals two frequency lines if we choose high enough line resolution The difference between two frequencies is the modulation frequency shown in the time domain 1 ifs Picture 27 BEATING IN TIME DOMAIN Picture 28 BEATING INFREQUENCY DOMAIN 9 Amplitude modulated signal Amplitude modulated AM signal is shown as two sideband frequencies Difference between the base frequency and the sideband frequency is the modulated frequency 10 Hz in this case also seen clearly in the time domain The rule here is the same like with beating to reveal the modulation we should choose high enough line resolution In fact the time signal which is the base for the FFT calculation should show some modulation peaks When windowing is used we know that the base band could be even 4 lines wide and the main band which is always the highest covers the modulation with low line DeweFRF v6 5
39. lines between nodes assigned to construction This is on off switch button Trace line switch is off When you switch all buttons off you can see a screen like this DeweFRF v6 5 User Guide v1 2 0 page 97 2007 DEWESoft FRF Setup Point Maker 4 4 Point Maker Point Maker is tool to graphically define and represent measured nodes and objects grids and circles points of mechanical structure for which fracelines and channels are defined for each excitation and response i 1 Point Maker can be opened with e click E tool of Geometry window toolbar in FRF setup or Analyse procedure e selecting New Geometry from FRF File menu With Point Maker we can define new or modify e Nodes e Trace Lines e Objects Point Maker has several Tools for your assistance for explanation click on field of interest Create or Sa Create or modify objects Geometry display tracelines grid or circle E LE setting nodes Symbolic display of global cordinate sistem After defining new Geometry of structure in Point Maker export Save it from DeweFRFs FRF setup For information about Import Export Geometry see User Guide gt Data management gt Geometry SUGGESTION because Geometry and Modal FRF Data are stored in same unv Universal format file it is strongly recommended to use separate filename for new or modified Geometry DeweFRF v6 5 User Guide v1 2 0 page 98 2007 DEWESoft
40. negative number is allowed too Using the left click the given cell is selected and a value can be entered The cells can be selected also using the Tab key for detailed description action with keyboard keys referto Navigation Keys Nodes TraceLines Objects After clicking Create under Grid parameters a grid is created using the above parameters Point Maker fe Creste Wh Tiscelines Tieceline 1 DeweFRF v6 5 User Guide v1 2 0 page 107 2007 DEWESoft Objects FRF Setup Point Maker Circle In the table of parameters values for the cells forthe Radius Number of Nods Offset distance from selected Plane along the coordinate perpendicularto this Plane have to be entered and the Plane selected Value of parameters is only a number Negative number is reasonable only in Offset parameter in Radius it is not meaningful in Number of Nods it causes unpredictable results deletes nodes of previous created circle Using the left click the given cell is selected and a value can be entered The cells can be selected also using the Tab key for detailed description action with keyboard keys referto Navigation Keys After clicking Create under Circle parameters a circle is created using the above parameters a or iF Er PAIE Nodes TraceLines Obiects tal a AA F Trace lines have to be defined separately DeweFRF v6 5 User Guide v1 2 0 page 108 2007 DEWESoft
41. problems Those were Hamming Hanning Blackmann Harris and others They have created assortment of functions which tries to correct the errors Window functions are multiplied with original time signal and because they are usually O at beginning and the end sine waves could be also in between lines or phase shifted and they will be less leaked over neighbor frequencies Picture 15 shows some of these functions in the time domain Hamming Hanning F lattes Picture 15 WINDOWS IN THE TIME DOMAIN And here is the most common question to FFT what are the differences between windows and when to use certain windows DeweFRF v6 5 Reference Guide v1 2 0 page 165 2007 DEWESoft Theory of single channel frequency analysis How can we at least try to avoid it The rule of thumb is when we want a pure transformation with no window s side effects for advanced calculations we should use rectangular window which is by the way equal to no window For general purpose Hanning or Hamming are commonly used because they provide a good compromise between fall off and amplitude error maximum of 15 This comes from the fact that old frequency analyzers didn t have that many possibilities in terms of frequency lines and these two windows have narrow sideband But still if 12 bit AD cards are used Hanning or Hamming is a good choice When more dynamic range is necessary we want to see very small signal among large ones
42. set Set frequency span Frequency span defines the upper frequency limit of the FRF This defines what will be the highest frequency which can be measured The maximum sample rate allowable will vary according to which A D board you have installed and how many channels are activated for recording In the drop down list choose appropriate frequency span Note The sampling rate is set to 2 1 28 Frequency span The factor 2 is the Nyquist factor for sampling and 1 28 is used to assure that the results will be alias free So if the frequency span is 2000 Hz the sampling rate will be set to 5120 Hz WARNING Setthe sampling rate before you do anything else this setting will also be used for the setup This important to achieve a useful scaling In Ch setup gt Analog tab we can set all the channels which will be used during measurement for explanation click on column D berm clock 7 Stat on erena tigger ett oo Beat se 19 AMA Mon LEE DeweFRF v6 5 User Guide v1 2 0 page 57 2007 DEWESoft FRF Channel Setup Analog Above the channel list we can select Analog nalog oul External clock T Estemalclock J Start on external trigger This option selects external clock as the source of acquisition Usually if this option is not selected the clock source is internal and defined by the sample rate selected in frequency span If this option is checked the source for a
43. the number of points the circle graphics shows the points which are selected for calculation in light green and next three points which are not taken are in dark green If it seen that dark green points would still be on the circle it is advisable to choose more points for calculation The Natural freq label shows the calculated natural frequency which is calculated from the mode circle The Struct damping calculates the damping from the angles of points in the mode circle Mode circle shows the points for calculation the circle is the result of fit and the red point shows the amplitude and phase of estimated natural frequency On Analyse toolbar we have two tools to export FRFs Copy to clipboard a Mei ee copy To clipboard button copies the currently selected and active FRF to the clipboard It is in tab delimited format suitable to be imported in spreadsheet applications The first column is the frequency in Hz the second column is the real part and the third column is the imaginary part UFF export az EN FRr data e nave Several Options tO export E Coherence e FRF data Pa Excitation data The UFF export exports the data in universal file format type 58 e coherence All data e excitation FFTs exports only the FFTs of the ast run or e all the results at once After selecting UFF export tool Save FRF data As window is displayed to save new or modified FRF Data measured data DeweFRF
44. three sine waves with the frequencies of 0 5 1 and 2 Hz and then the decomposed signal Picture 2 5 5 a a 16 Picture 1 ORIGINAL SIGNAL Picture 2 DECOMPOSED SIGNAL Just to make those sine waves better visible let s show them in a nicer way picture 3 On x axis there are frequencies and on the y axis there are amplitudes of the sine waves DeweFRF v6 5 Reference Guide v1 2 0 page 159 2007 DEWESoft Theory of single channel frequency analysis What is frequency analysis 0 2 4 E B 19 Picture 3 DECOMPOSED FREQUENCY DOMAIN DATA And this is really what the frequency analysis is all about showing the signal as the sum of sinus signals And the understanding how that works helps us to overcome problems that it brings with it 2 2 Theory of frequency analysis Frequency analysis is converting time domain data to the set of sinus waves So the theory says But like more if we say that frequency analysis checks the presence of certain fixed frequencies Let s look at the equation of discrete Fourier s transform to figure out why 1 X ko Y x n c0s 2 1 k n N j sin 2 1 k n N 0 Let s think about how does it work To check the presence of certain sine wave in a data sample the equation does the following 1 Multiplies the signal with sine wave of that frequency which we want to extract Pictures 4 and 5 shows the signal with black line which only consists of sine wave
45. tn re 66 NOUS j jg qq nn tn dir 67 o p Fi RP DREN He rama tani duncan tela anne Rian Nii A 68 AAA AREER A 69 dynamic representation A RRA 70 Gymamie AB NA 71 Analog CUE ion 73 Funcion Generator oeste icrti ea cette ce ne 74 Operation modes 2007 DEWESOft DeweFRF 6 5 User manual v1 2 0 Contents ll o 2 natditatst unclean tech abinetia shies a aa a 78 PACUVALING outputs ON OMR e ae ett 79 CHAN valle O 1 ce au eme 79 Wavelo may pe O O a ia 80 Channel SST dd dd as des e ds la 81 Noise AGORA SSI errada ee ee au 83 Arbitrary Additional settings LL de 84 FRF S t p g aaa 86 FRF Property DANS Sein tos 87 SOMOM omic 87 Continuous shaker eXcilatlon 54m eme dia den ns 90 Impulse hamimer excitatlon aks aie ei ee ee ee 91 Transfer function Selector ss ssssssrssensrsneensseneeensseneennsneneensseneennsnnes 92 Geometry WINCIOW a ii 94 Geometry window toolbar ie 95 Manipulate gemelo aa 95 DISPIAVSEUING O ads a 96 PORN O O ANDES 98 NES A oc 99 RL A toas 102 So o nar ete E ES 107 TOOS AAA NM MO nee 110 Measure qjg Rana aci 112 Graph Display aaa 113 Measurement gg qj a ess nren a diet nnna 118 Ec 101 CI 2 en 2 ste aae ns eus 119 Analyse qj qj ada 120 List f m as red FRES SR ne ner terne ei Ne rfi 121 FREIRE 122 Geometiy WINGOW aia Ras 124 PMAIVSISTOOIS iria ccada 126 ANMI nn M Ne A dE Ass icnes 126 2007 DEWESOft DeweFRF 6 5 User manua
46. v6 5 User Guide v1 2 0 page 131 2007 DEWESoft Export FRFs Analyse Analysis tools to uny Universal file format data file also see Data management gt Modal FRF data Save FRE data As My Recent Documents Desktop My Documents er My Computer tn a E Moja mre a The pue Info button shows the information about the settings of the project used to take FRFs The comment can be added to the project and this project info can be saved to file or printed out gt fit En EE To clipboard UFF export DeweFRF 6 4 settings file Date 29 04 2006 Project Comment Frequency span 000 Lines 00 Start frequency Stop frequency 235 Scope tigger value Scope trigger pretime Stop on overload false Stop afters averages not set FAF calculation method H1 Exported files C DewetronProgramsDE We Sofths 4op4 0 eweFRF Se tupe Elmer ur DeweFRF v6 5 User Guide v1 2 0 page 132 2007 DEWESoft Offline calculation 7 Offline calculation During extensive calculations we can Store time data in file Later we can reload calculate and analyse these From stored data The way to calculate is exactly the same except that the data is not acquired but loaded from file Offline calculation and analyse include following steps procedures e Store time data store segment of measured data in Channel setup procedure of directly measurement e From s
47. window e Save Saves actual geometry in Project not to the hard disk later with particularly action together with other projects data in dfs Dewesoft FRF project data file e Cancel Leaves Point Maker without any change to actual geometry Manipulate and display geometry A KER e Pan L When this button is pressed we can left click and drag the mouse inside the geometry widow to move the geometry on geometry window 2 3 When this button is pressed we can left click and drag the mouse inside the geometry window to rotate the geometry on geometry window When this button is pressed the same is achieved with rotating Global coordinate system We can left click and drag the mouse inside the Local coordinate system to rotate the geometry on geometry window e Rotate e Zoom When this button is pressed we can left click and drag the mouse anywhere inside the geometry widow from outside to center to extend zoom in the geometry or drag the mouse from inside outward to contract zoom out the geometry e Arrow When this button is pressed we can observe in Geometry window arrows and directions of excitation or response in constructions points This is on off switch button BA When this button is pressed we can observe in Geometry window all numbers of nodes assigned to construction This is an on off switch button da mee Di When this button is pressed we can observe in the Geometry window all the trace
48. with 50 Hz We try to extract the 36 Hz on picture 4 and 50 Hz on picture 5 they are shown as blue lines Light blue filled wave shows multiplied values 2 Multiplied values are summed together and this is the main trick If there is a component in signal like in picture 5 the multiplication of positive signal parts and extraction sine waves gives positive result Also the multiplication of negative signal parts and negative extraction sine waves gives the positive results observe picture 5 In this case the sum of the multiplied sine waves will be nonzero and will show the amplitude of the 50 Hz part of the signal In the case of 36 Hz there are both positive and negative sides of multiplication values and the sum will be almost as we will see further on zero 3 And that s it That sum gives the estimate of presence of frequencies in the signal sample We check sine and cosine to get also phase shift in the worst case if phase shift would be 90 deg sum of sine functions would always give zero Picture 4 UNSUCCESSFUL EXTRACTION Picture 5 SUCCESSFUL EXTRACTION DeweFRF v6 5 Reference Guide v1 2 0 page 160 2007 DEWESoft Theory of single channel frequency analysis Theory of frequency analysis The principle shown above can extract basically any frequency from the sine wave but it has one disadvantage It is awfully slow The next important step in the usage of DFT was the FFT algorithm Because there is mo
49. 0 page 3 2007 DEWESoft Basis of work with DeweFRF 2 Basis of work with DeweFRF DeweFRFs base DeweFRF modal analysis software to be based upon Signal generator DeweF RF includes full featured signal generator with 16 or more signal outputs There are different modes and many functions for each mode Measure To measure back excitations and systems response There are two ways of making the measurement gt directly or offline Analyzing Analyze stored FRFs and determine system characteristics It will also help to evaluate measurement results Measurement methods Before trying to setup the measurement let s notice that there are two ways methods of making the FRFs measurement 1 first way is to measure the FRFs directly while acquiring data From measure and the 2 second way is to measure and calculate respectively offline From stored data Decision what to do depends on the user if the archive time data is needed and on the system performance The system benchmarks might differentiate from system to system but with recent computers 3 GHz P4 itis possible to measure online 256 channels at few kHz bandwidth There are two method to generate input signal excitation and also measurement Impulse measurement input signal excitation is generated with modal hammer Continuous measurement gt excitation with function generator or shaker Fordetailed information see Measure methods Ba
50. 10 75 Hz 0 093 s 4096 2 685 Hz 0 372 s 16384 0 67 Hz 1 496 Table 1 EXAMPLE OF FFT SETTING So the number of lines combined with sample rate also defines the speed of the FFT when non stationary signals are applied With more lines FFT will appear slower and changes in signal will not be shown that rapidly Different amplitude scales of FFT can reveal more about the signal if used correctly Linear amplitude scale gives the best view of maximum peaks in the signal logarithmic can show more invisible peaks and signal noise but gives worse comparison of high and low peaks Scale in dB gives the best estimation of signal noise if O dB is maximum measurable value and is also used in noise measurements where the dB scaling is actually the result since the human ear has logarithmic sensitivity to noise IE CERN CES ON OR CONNUS CONS CN CN mo m ppp am m e om en a o mn me T m ne om om ee a mm Picture 7 LINEAR AMPLITUDE SCALE Picture 8 LOGARITMIC AMPLITUDE SCALE The pictures 7 and 8 give good overview about the differences in linear and logarithmic scale In linear scale picture 7 noise and the peak at 140 Hz is not even visible But on the other side peak at 140 Hz is 100 times lower than the other two and that difference is not very well visible in logarithmic scale picture 8 In the real world often there are lots of sine waves or spikes in the signal and linear amplitude display shows most relevant only
51. 6 5 Tutorials v1 2 0 page 28 2007 DEWESoft SISO Single I O modal analysis tutorial Channel setup ri Li hannel setup for channel 2 Sensors Resp Minvalue PTE UT Next step is to define the FRF setup JON Programm EL MOOHERHE Ne modules A DeweFRF v6 5 Tutorials v1 2 0 2007 DEWESoft page 29 SISO Single I O modal analysis tutorial FRF setup 3 2 FRF setup Creating Geometry For SISO it is very helpful to first define the geometry In our case it is a simple beam structure with eight points We can import the geometry with Import menu gt Geometry item or create the geometry with File menu New Geometry In this case we can go to Objects tab sheet create the grid with 8 points in x direction and 1 point in y and z direction We check create with tracelines and press Create button The beam structure is generated We close the window with Save button Point Maker _ lol xl Modes TreceLines Objects if rape Be GRID ra E Ea eee Auto Scale Save Cancel FRF Setup In the FRF setup we select the Triggered mode First we define the bandwidth of measurement We have to know that we can achieve only few kHz of bandwidth with modal hammer so more than this is not reasonable Then we define the number of lines The bandwidth is divided by the number of lines to get the frequency resolution
52. A Ch saup FFFesuip penture nasale Dagia Dalkia al Fermani sii Fist Greeti Tociptoed LFF expor ha Fit panis E Natural beg AE Sanel damping 0024305 Phase FA eects vom bu Les 2 FRE Diyoko mcm e As with all other tests the FRFs can be exported to the universal files or copied to clipboard see User Guide Analyse Export FRFs DeweFRF v6 5 Tutorials v1 2 0 page 36 2007 DEWESoft Project management tutorial 4 Project management tutorial In Dewesoft FRF there are many ways to Import Open or Export Save setup geometry and measured data type of file type of data action Channel Setup Setting of all analog channels for excitation and responses FRF Setup Project Assigned points of structure to channels and New Open x i setup parameters for calculation dfs Dewesoft FRF project datafile Save Save as Geometry Defined geometry and nodes of mechanical structure Project doesn t include measured data Measurement Setup Channel Setup dss Dewesoft setup data file or Setting of all analog channels for excitation Dewesoft text setup file and responses Geometry Geometry New Import P Defined geometry and nodes of mechanical unv Universal file format data file du ce J Export Modal FRF Data RU aes Import unv Universal file format data file Export DeweFRF v6 5 Tutorials v1 2 0 page 3 7 2007 DEWESoft Projec
53. DeweFRF v6 5 Reference Guide v1 2 0 page 153 O 2007 DEWESOft Analog HW Device DeweFRF System setting Hardware setup If you want to run the software in purely demo mode i e if you do not have either a National Instruments Data Translation Microstar iDSC or Microstar DAP A D card in computer select in System Hardware setup Analog tab Analog device from the drop down menu No A D hardware UN o A D hardware and then choose in Number of channels how many signals the system should generate for you 4 8 16 are popular numbers To indicate the demo mode Dewe software displays No hardware Running with test signals and the Registration status displays DEMO You can running Dewe FRF software on a computer with DEWE ORION 1624 most National Instruments cards most Data Translation cards most Spectrum and Microstar s DAP boards in PROF real mode Before use DEWE software in real mode you have to install appropriate Hardware driver Dewe software will automatically identify the A D card that you have installed and set it up for you DeweFRF v6 5 Reference Guide v1 2 0 page 154 2007 DEWESoft Analog HW Device DeweFRF System setting Hardware setup for explanation click on appropriate part of screen There will be nothing special that you need to do expect of selecting the right manufacturer from the drop down menu in
54. DeweFRF v6 5 User Guide v1 2 0 page 46 2007 DEWESoft Data management Project file Save project Export We can save existing or new project by selecting HE File menu Save project Ce New project By new project Standard Save As window is displayed see Save as New geometry Open project l da pen proj Warning existing project is saved under same project name and overwrite previous data Save project as Export New project We can save existing modified project to the new setup file by selecting New geometry G Open project File menu Save project as SF Save project E beam_dfs E Hamm_12Feb dfs 3 Palicas Proj Test dfs A Pacadt dfs DeweFRF v6 5 User Guide v1 2 0 page 47 2007 DEWESoft Data management Measure setup file 2 2 Measure setup file In Measurement setup dss Dewesoft setup file or Dewesoft text setup data file Channel setup data are stored Import We can also directly Import Load Measurement setup data from dss Dewesoft setup file or Dewesoft text setup data file by selecting fw Modal FRE Date Import menu Measurement setup The standard Open window is displayed for loading existing Measurement setup from dss file My Recent pa Palica9t ds5 e Desidop 5 My Documents r mi My Computer Moje mets
55. E 2010 DEWE 4010 DEWE RACK or DEWE BOOK series product then you should tell DEWESoft which COM PORT these modules are communicating on WARNING Please check this to ensure that you have the correct com port as incorrect settings can cause your system to hang up or disable other devices that are already using the same com port Please notice that the communication speed is fixed to 9600 for DAQP MDAQ series modules Activate TEDS support TEDS sensors are supported by some DAQP MDAQ series modules When DAQP MDAQ modules is active the TEDS support can also be activated for these modules by check Use TEDS sensors Activate Dewetron PAD EPAD modules To activate PAD series modules support click on the Use PAD modules checkbox and select in COM port the serial interface which is used for the communication If you are using an expansion rack with additional modules or EPAD series modules you can select Additional PAD channels to make them available If you are running this software on a computer that does not have an A D card or other required hardware you can press the CANCEL button on Hardware setup screen which will cause the software to generate waveform data for you to allow the software behave realistically After starting Dewe software if the program does not automatically show Hardware setup v dialog box it should the first time you run it please use the System menu and select Hardware setup
56. EWESoft Analyse In FRF Analyse we can analyse frequency measured response data Analyse procedure is relevantto analyse measured data which are acquiring directly with continuous or impulse excitation or for offline calculation gt see displays measured FRFs with different Display options the list of measured FRFs is the selector for the display these on the graph of mechanical structure with nodes tracelines as well as local coordinate system for observing the deflection of shapes with animating the points on the structure or to show the maximum deflection shapes Animation Max shape or Circle fit tools for export FRFs and information about the settings of the project used to take FRFs About Import Export FRF setup data as Project data file see gt About Analyse for offline calculation see gt 4 When FRFs are stored the Analyse window can be started by click on e FRF tools button or starts automatically when Stop button is pressed in Measure tool for explanation click on field of interest Ele import Export System Analysis toolbar ie Oxo A ACA En an Ch setup FRF setup Mears Analyse Delete Delete al frenada Mas shapa Cicle ft To chpboard UFF esporl Info i i a Exc Rese gg ae FUR E e RJ Bip BJ me ns ce Mn ce ee pul pl Measured FRF curves of selected channels List of measured excitation response points channels Pa r Pa I
57. Objects FRF Setup Point Maker Navigation keys lt tothe previous cell in the same line in number one digit left and from first to the previous cell gt tothe next cell in the same line in number one digit right and from last to the next cell Tab tothe next cell from Z also to X of the next line for Grid from last to first cell for Circle Shift Tab tothe previous cell from X also to Z of previous line for Grid from first to last cell for Circle T up one cell in the same column up one parameter downone cell in the same column down one parameter Home to the X coordinate of the same parameter in number to leftmost digit and then to the X coordinate End to the Z coordinate of the same parameter in number to rightmost digit and then to the Z coordinate PgUp first parameter in the column PgDn last parameter in the column Enter selectthe entire number in the cell Backspace deleting the left digit in number while editing the coordinate or entire number when this is selected Delete deleting the right digit in number while editing the coordinate or entire number when this is selected DeweFRF v6 5 User Guide v1 2 0 page 109 2007 DEWESoft Tools FRF Setup Point Maker Point Maker has the following tools for your help e Common and Objects tools e Nodes tools e TraceLines tools Common and Objects tools Save Cancel e Auto scale Scale display to fit in actual size of Geometry
58. Point Maker screen by selecting Import menu Geometry DeweFRF v6 5 User Guide v1 2 0 2007 DEWESOft page 50 Data management Geometry Standard Open window is displayed for load existing geometry from unv data file Look in O Setups 1 eE CroularPlate ur Cube unv Eimer ums EimerFRFs uny Eimer Geo un 2 Hammi_1 eb unv Hamm2_12Feb Lrnr Hamm3_12Feb unv Pabea4 Help osn uny Pabca6_bestumy My Computer CCEA is Moja mre a Fleseftype fUriverlficfomat ll Mall Eventually modify existing dataandafterward Export geometry Export geometry ES File After defining new or modified geometry we can export save Te geometry by selecting Export menu Geometry she BeamTast un e 1 CroularPlate uny Cube uny d ni EJ Eimer uriy EmerFRPS ue pa 4 Elmerteo ur My Documents Hammi_12Feb ur 2 Hamm2_12Feb un pe un My Computer 2 Paica4_Help_osn uny Palca _test uns Moja meja Savesshoe Unvana fle formar Cancel WARNING because Geometry and Modal FRF Data are stored in same unv Universalformat file it is strongly recommended to use separate filename for new or modified Geometry DeweFRF v6 5 User Guide v1 2 0 page 51 2007 DEWESoft Data management Modal FRF data 2 4 Modal FRF data In Modal FRF data unv Universalfile format data file measured data are stored Import Modal FRF Data We can directl
59. ROR AND LEAKAGE OF THE FFT NO WINDOW 2 Leakage Also we observe that especially if the sine wave is not on the frequency line we get high amplitude values on both sides of the main band The amplitudes are really high with no window it is about 10 of the original values for about 10 neighbor lines If there is another sine wave in the signal in this region which is lower than this 10 it will be completely hidden by the leakage effect 3 Aliasing The other problem comes from the fact of the signal conditioning If simple A D converters are used the sampling frequency must be at least twice higher than the maximum frequency of the signal This effect is called aliasing effect Picture 12 shows the reason for it Vertical lines represents samples taken with A D converter and the blue line is the original signal But if we look at the red line which is the signal form A D converter the signal is totally wrong because too fewer samples per period were taken to correctly represent the signal Picture 12 ALIANSING Of course the problem above is not FFT problem but it is very important to know to correctly identify the cause for the error And sometimes there are some lines in FFT which can be only explained in terms of aliases In FFT if we change the frequency to the ranges above the maximum frequency limit that line will not disappear but will bounce back and will show the fake frequency DeweFRF v6 5
60. Y or Z and sign or combined in for example 12Y Then you can define the excitation channel by clicking on the first column In this row we also define the index direction and sign of the measurement point Generator does not have any effect at this point The same is valid for the response channels Number of response channels is number of all selected channels minus one used for excitation For detailed information see User Guide FRF Setup Define Geometry The geometry can be loaded from unv file by selecting Import Geometry On Point Maker screen you can define geometry nodes of mechanical structure trace lines as well as global coordinate systems of the nodes are supported When entering points arrow with indexes directions and signs will be shown We can left click and move the mouse inside the geometry to rotate move the geometry and to zoom in and out the geometry For detailed information see User Guide Point Maker DeweFRF v6 5 Tutorials v1 2 0 page 15 2007 DEWESoft Four step tutorial Measure 1 3 Measure ato The Measure can be started by clicking the _ ese FRF tools icon Ale Import Export System vie He AR Ex Aj E EE ar ro Snake Aerea FE epee level Fh Slag Cone Fo Meteo FLT Haas F1 CA sola FRE setup Rispa Portinsar 17 Asp az ie ae Lines ii eke i Be ea E X Fj ag eset Fo Reject last F6 Stop ConfimiF3 Meytexc FIG Ment r
61. a measured data System menu DeweFRF Ra Ln pa le General and Hardware setting for work with DeweFRF software LE Ch setup FAF setu dt Hardware setup DeweFRF v6 5 User Guide v1 2 0 page 147 2007 DEWESoft Part Reference Guide DEWE software can be used with recommended system hardware and software System requirements Before installing DEWE software for working in real mode you have to install appropriate Hardware Hardware driver s and licence key Licensing Before use DEWE software first of all choose is appropriate DeweFRF System setting in System menu In this guide is also information about Theory of frequency analysis and H1 H2 and Hv calculation algorithms DeweFRF v6 5 Reference Guide v1 2 0 page 149 2007 DEWESoft DeweFRF System setting DeweFRF System setting Before use DeweFRF software e for working in REAL mode you have to install appropriate Hardware and Hardware driver s After installing software you have to install licence key Licensing e first of all choose is appropriate hardware and general setting In DeweFRF System menu you can choose DeweFRF File Import Export System ste T l Ez EE zs ES General settings i p General setting and most important Ch setup FRF setul Hardware setup Mr Hardware setup 1 1 General setting General settings FF Beep on bigger We turn on and off sound sig
62. al A D boards or other sources In this case DEWETRON can create a License file dwcode which you can load to register your software Right click in the licensing tab and select Load license code s from file DeweFRF v6 5 Reference Guide v1 2 0 page 158 2007 DEWESoft Theory of single channel frequency analysis 2 Theory of single channel frequency analysis Frequency analysis is widely used tool because of its power to reveal the real nature of dynamic signals Working for many years in practice doing measurements and lately also developing FFT analyzers it became very obvious knowing the theory of frequency analysis helps to reveal the problems we can anticipate and the ways to get around them This article helps to understand the theory and answers some of the most asked questions regarding FFT e What is frequency analysis e Theory of frequency analysis e Properties of the Fourier transform e Where we can get in trouble with the FFT e How can we at least try to avoid it e Averaging how to further enhance the results Representation of different signals in the FFT e Conclusion 2 1 What is frequency analysis Frequency analysis is just another way of looking at the same data Instead of observing the data in the time domain with some not very difficult yet inventive mathematics frequency analysis decomposes time data in the series of sinus waves Picture 1 shows the signal which consist of
63. al screen with selected e is displayed depending on hardware you can running Dewe FRF software on a computer e that does not have an A D card in DEMO mode or e with DEWE ORION 1624 most National Instruments cards most Data Translation cards most Spectrum and Microstar s DAP boards in PROF REAL mode For DEWETRON modules you can activate this modules Before use DEWE software in real mode you have to install appropriate Hardware driver s for explanation click on area of interest ai Analog CAN GPS Video Math Timing Alarms Analog out Plugins Licensing Dewetron DSA ee com Card FOUND I Use TEDS sensors scons Use DAGN modules Card setup Grouping D 16 bit mode T use onboard AS485 r use onboard AS5485 for additional ORIOM 1624 200000 PROF E _ Cancel Grouping independent each group can have different number of channels and start at any channel number required e For high channel count applications is also available Channel The grouping can be done completely DeweFRF v6 5 Reference Guide v1 2 0 page 151 2007 DEWESoft Analog HW Device DeweFRF System setting Hardware setup Before installing DEWE software for working in real mode you have to install the A D board drivers Be aware that the proper drivers are installed according to the following hardware driver list Devices r Driver version DAQ and PAD sones DEWE
64. an enterthe channel name as usual text MS Navigation keys are same as in other Windows application You can also enter this texton the Channel setup screen General part of A 250 e Analogin channel see gt Analog Channel setup or MD EE e Analog out channel see gt Analog out Channel setup Back to Analog channel list Back to Analog out channel list DeweFRF v6 5 User Guide v1 2 0 page 60 2007 DEWESoft FRF Channel Setup Amplifier type and ranges Analog Shows the DEWE Module currently installed in this slot AMPLIFIER 014 HDAG ACC inane 2500 m 300 k 1 HDAQ ACC SNCESSaN 500 mv 300 k MDAG ACE Sha 2500 mi 300 k HDAG ACC SADO 2500 mv 300 k HOAQ ACC SNA 2500 mv 300 k HDAQ ACC SM T3400 500 m 300 k HOAQ ACC ASADO 2500 mv 300 k HDAD ACE SIDO 2500 m 300 k HDAQ Baze 0111111 e for DAQP MDAQ module it will show the name of the module and the range selected e for DAQN or DAQ series non programmable module onlythe name is shown e for PAD series module the name and range are shown A small arrow I on the right side of the field is running through all fields indicating that all channels are scanned for new amplifiers or settings When you click on one of the Amplifier columns header line with al a selection field will appear In this field you can choose from different options which will have an effect on al
65. analysis Please click on caption or picture for detailed explanation of the certain step CHANNEL SETUP Set all the analog channels which will be used during measurement excitation and sensors FRF POINT amp GEOMETRY SETUP Define geometry and nodes of mechanical structure assign points and setup parameters for calculation MEASURE Acquire frequencyresponse data ANALYSE Animating shapes calculate damping and export data to UFF and clipboard DeweFRF v6 5 Tutorials v1 2 0 page 8 2007 DEWESoft Four step tutorial Channel Setup 1 1 Channel Setup Bog The Channel setup can be done by clicking the Ru icon on FREs tool bar In Channel setup we can define Set all the channels which will be used during measurement in Analog and Analog out tab Measurement method From measure default or From stored data see Calculation tutorial for offline calculation Set frequency span maximum sample rate allowable About Import Export Channel setup data see Project management tutorial When the Channel setup are done go tothe next step FRF setup for explanation click on field of interest 5 abs tae Live measurement Maxi mn LE Et Import Export System DIRECTLY while SE RS z PTI A ett acquiring data Ch setup FE Se He nay mm a namme e E b From Store data during expensive calculation and reload it recalculate and analyse it later
66. ated by the left mouse click and deactivated by the right click You can set any channel to auto mode DeweFRF v6 5 User Guide v1 2 0 page 62 2007 DEWESoft Input zeroing Zero FRF Channel Setup Analog If you click on the Zero El button the following selection window appears mn E Zero all AUTO channels Zero Reset all AUTO channels Calibrate first point on all AUTO channels Zero Calibrate second point on all AUTO channels Calibration tmebase 0 15ec Ave Pf O isec Ave 1 0sec Ave e Zero all AUTO channels option will perform a channel zero for all channels set to auto e Reset all AUTO channels will set zero offset to all channels e Calibrate first point on all AUTO channels option allows to calibrate all the channels at once Usually this is useful when the CAL signal is available on all the inputs If we have the option to put electrical 0 and for example 80 on all the channels we can enter the 0 as the first point in the channel setup and 80 as the second point in the Channel setup for each channel set all the channels to AUTO and then first apply 0 press Calibrate first point then apply 80 and press Calibrate Second point on all AUTO channels e We can also choose the Calibration time base as 0 1 sec Ave or 1 0 sec Ave same as in Channel setup 0 1 second will give faster response time while 1 second will provide more averaging time to perform calibration Back to Ana
67. ax thaps Cice To clipboard UFF export Info Reseau In single FRFs which have inadequate results can be measured again by pressing SA ce button also see gt DeweFRF Tutorial gt SISO single I O modal analysis If the geometry has been created or loaded the deflection shapes can be observed with animating the points on the structure ate BEFA By choosing Animate button currently selected operation deflection shape will be animated wi Complex l The speed and amplitude can be changed with the buttons on the Geometry display see Real Geometry window SCALE and SPEED Imaginary DeweFRF v6 5 User Guide v1 2 0 page 126 2007 DEWESoft Animate Analyse Analysis tools The drop down menu gives the choices to animate e complex e real or e imaginary parts of the currently selected mode Usually complex animation is used but often it is useful to animate only imaginary part of the results because with well separated modes the real part of the results is only the measurement error re gt After selecting Animate button instead of this we get Stop button to stop animation EA ERES however Max shape button is disabled LS EE Fie import Export System Ge ba e BE Lx BA 45 M az Eh selup FAF Fat Cekule finado i _ Delete Delete a Slop ere si MES Cuck ft To chpbosed UFF export inio In the abo
68. before you do anything else this setting will also be used for the setup This important to achieve a useful scaling By OFFLINE CALCULATION From stored data we can t choose the frequency span because it is defined by the sampling rate of time domain data which is loaded DeweFRF v6 5 Tutorials v1 2 0 page 12 2007 DEWESoft Four step tutorial FRF Setup 1 2 FRF Setup The FRF setup can be selected by clicking the FRF setup tool icon In FRF setup we can define Geometry of mechanical structure with nodes trace lines as well as global coordinate systems Channels assignment excitation and responses channel adding removing excitations or responses and changing pointindex FRF property frequency span number of lines calculation method and FRF Calculation type free run or triggered acquisition with all of its property About Import Export FRF setup data see gt Project management tutorial When the Channel and FRF setup are done go tothe next step gt Measure for explanation click on field of interest Dewef EF Ele mort Export Svp FRE property panel for add and remove gt A Es E B ti f excitations responses Ch shp FAF up elo Ws dd Ferme Add Fermes FRF setup toolbar TRANSFER FUNCT ION SELECTOR Channels assignation and changing Point index of Excitation and Response channels a a e l e A m4 MPT Bas MAI 1 Defi
69. channel Now press the Add button to enlarge the table to the required number of groups In our example we would like to define 4 groups therefore we need 4 rows 16 Group 2 Er 2 Group 3 48 Ej DeweFRF v6 5 Reference Guide v1 2 0 page 156 2007 DEWESoft Analog HW Device DeweFRF System setting Hardware setup The following columns have to be filled out e Group name Can be any name just helps you to identify the group e Channels Number of channels within this group in our example always 16 e Start index The number of the first channel within the selected number of channels e Prefix The channels are named automatically from 0 to the selected number of channels as this will cause multiple entries with same channel names a prefix will be added Can be any text try to keep it short After you have done this settings the groups are already available in the Setup Since DEWE Software 6 2 an analog output is available for Nationa Instruments M series boards This function is only available with Function Generator option in DEWE software For test issues set the hardware to Test AO Hardware setup Tx j GPs Video Math Timing Alarms F natog out Plugins Licensing Card FOUND P Hera FF idee padem Analog CAN alog out I kir ae Please find more information about analog out in User Guide gt Channel Setup and Measure The mathema
70. cquisition comes from an external clock source such as encoder or external oscillator Start on external trigger We can select this option to start the acquisition on external event This option is useful when we want to start capturing data not on the start of the measurement but on external digital event It is most useful with extremely high sampling rates but in a lot of cases the software trigger is better because we see the dataeven before the trigger occurs and we can also use pretrigger Columns in the channel list explained First let s look at the columns that are shown in your analog channel list and describe what each is for Slot input channel On Off activate deactivate channels C channel color selector Name channel name Amplifier amplifier type and ranges Physical values current input values Zero remove offset Setup input settings and calibration This column indicates the number of the channel It always starts with 0 and counts up to the maximum number of available output This column is a direct reference to the slots within your DEWETRON system If you have a DEWE 3010 or DEWE 3000 the first 8 0 through 7 slots are the ones on the mainframe itself and the second group of 8 slots pertain to either the BNC inputs or RACK 8 3010 expansion rack depending on the configuration of your system If you have a DEWE 2010 DEWE 4000 DEWE RACK 16 or DEWE BOOK 16 then each slot pertai
71. d show time which can be positioned in two ways e Move mouse cursor to the first position of interest Click measurement cursor appear in this point and hold left mouse button and move on mouse cursor appear measurement cursor Il and move whit him to the second position of interest e Drag the first cursor from eft side of the graph to the position of interest and the second cursor from the right side of the graph when mouse point on vertical line of measurement cursor mouse cursor change to two sided arrow which indicate feasibility to move measurement cursor A E i well DeweFRF v6 5 User Guide v1 2 0 page 139 2007 DEWESoft Display of stored data Offline calculation Channel setup In both case we can zoom into the selected area with e Move the mouse between these two measurement cursors it will change the appearance immediately to he Then simply do a left mouse click to zoom into the selected area To undo the zoom just use the right mouse button and you will zoom out step by step e Do a left mouse click on MM button on right side of graph to zoom into the selected area To undo the zoom use amp button below and you will zoom out step by step After zoom into the selected area you will see now more details Jolxi Ele Import Export System Ch senap FAFselup Calculate Anabse i From stored deba F e path TRIEGER ME pr gt muna at CT ar by o The signal ove
72. d if we click on coherence curve the value of coherence in this point is displayed see graph above The coherence is used when multiple data is acquired for single FRF e The other two selections are inear or logarithmic amplitude and frequency plots DeweFRF v6 5 User Guide v1 2 0 page 122 2007 DEWESoft Analyse FRF graph Typical coherence FRFs display j 726254 Amp 1 3971 Coh 0 958 _ o E aY p o Le Tianster cure 1 0E 1 Coordinates Scaling Transfer curve of FRF graph has x and y coordinates scaling possibilities 1 Edit minimum or maximum value for x and y coordinate of Transfer curve If we move with the mouse over the minimum or maximum value for x and y the cursor change Ea we can enter custom value by clicking with left mouse button and entering the value for X max x fOr Y min After editing we can see FRF graph like below 150 che Angle deal ioc 180 i dr 5 ai Th La e DeweFRF v6 5 User Guide v1 2 0 page 123 2007 DEWESoft Analyse FRF graph 2 Coordinates scale of FRF graph For FRF graph we have also the Auto scale y axis If we move with the mouse left to y coordinate of FRF graph the pointer change to k4 and we can by left click gt Auto scale y axis right click gt Full scale y axis With selected IS cursor changes in yellow vertical line and we can with eft mouse click and
73. de Analyse Export FRFs About Import Export Measured data see Project management tutorial For detailed information see User Guide Analyse DeweFRF v6 5 Tutorials v1 2 0 page 18 2007 DEWESoft Calculation tutorial 2 Calculation tutorial This tutorial will guide you through basic steps to do modal analysis based on Dewesoft data files If number of channels or frequency span is too high to calculate the FRFs while acquiring data we can stream the time domain data and later recalculate the FRFs from the streamed file This tutorial uses EimerNoise dsd and EimerGeo unv files which can be found on installation CD and can be used to follow the steps in this tutorial please click on caption or picture for detailed explanation for the certain step STORE LOAD DEWESOFT TIME DATA Loads Dewesoft data which will be used for calculation FRF POINT GEOMETRY SETUP Define geometry and nodes of mechanical structure assign points and setup parameters for calculation CALCULATE Calculate frequency response data ANALYSE Animating shapes calculate damping and export data to UFF and clipboard DeweFRF v6 5 Tutorials v1 2 0 page 19 2007 DEWESoft Calculation tutorial Channel setup 2 1 Channel setup STORE LOAD DEWESOFT TIME DATA A The channel setup can be selected by clicking the icon on FRFs tool bar Time domain data is stored in Dewesoft format with extension d
74. de more cycles at lower frequencies Startup time ts and a Fall time tf define the ramp slope at the beginning and the end of the sweep Two Sweep modes are selectable Single and Loop In single mode you will get a single sweep output only at loop mode the sweep is output continuously Ans log Analog out Fixed IE ll LUE sweep 8 Burst E Chirp Po is So Used Applications Sweeps are useful for testing electronic circuits like filters as well as in automated modal analysis DeweFRF v6 5 User Guide v1 2 0 page 76 2007 DEWESOft OO Function Generator FRF Channel Setup Analog out Step sweet The step sweep mode is a special procedure for modal testing where the signal remains at certain fixed frequencies to allow the structure to settle to that frequency In addition to this more exact frequency resolution of transfer function can be achieved with smaller steps Even though this procedure is the s owest to finish the test it provides most accurate results In the middle the frequency steps can be one channel defined as the trigger channel and this one can trigger the acquisition system to take results of modal test Start freq f1 and End freq f2 have similar function to sweep mode Delta frequency df defines the width of frequency change during Sweep time Sweep time t1 defines the sweep duration to the next frequency step Hold time t2 sets the duration where the frequency keeps
75. de of 0 0001 we would never see it because the 10 5 Hz frequency leakage is bigger than requested frequency But for example if rectangular window is used we would never see even signal with amplitude of 0 01 DeweFRF v6 5 Reference Guide v1 2 0 page 166 2007 DEWESoft Theory of single channel frequency analysis How can we at least try to avoid it Picture 18 WINDOW PROPERTIES DESCRIPTION For different kind of windows table 2 shows the values of all window properties This is a numerical representation of above mentioned rules Window type mum Highest sideband Sideband slope Rectangular El i 23 20 didecade Hanning ine OA 0 dh decade Hamming i iby 20 dh decada Blackmann 2 3h 12 40 db decade 20 db decade Table 2 WINDOW PROPERTIES Picture 19 shows zoomed FFT of the pure sine wave which fits to the exact frequency line Abscissa axis shows the lines value In normal FFT only values of the 0 1 2 etc are calculated so only those values are shown in the FFT We can see width of the first sideband highest sideband and sideband attenuation very clearly Y A AL A as c MAN O AR EU a ll Il LLL i Picture 19 WINDOW PROPERTIES If a signal sine wave frequency falls between two lines we see only the values of 0 5 1 5 2 5 which always produces higher sidebands This is best seen if we take the function generator set the frequency to exact frequency line set the amplitu
76. de scaling to logarithmic and the FFT will look fantastic No leakage exact amplitude Now switch the frequency from function generator to the one between two lines in the FFT and the result will be just terrible large amplitude errors huge leakage There is one more trick with windows if we are sure that all the frequencies will fall on its frequency lines rectangular window will give us the best result For example to measure the harmonics of the power line 50 Hz in Europe or higher 167 DeweFRF v6 5 Reference Guide v1 2 0 page 2007 DEWESoft Theory of single channel frequency analysis How can we at least try to avoid it choose 6400 or 9600 sample sec sampling rate that the line resolution will give exact 50 100 150 Hz FFT lines choose rectangular window and observe the perfect result in the y log scale 2 6 Averaging how to enhance the results To enhance the result we can use averaging of the signal in the frequency domain There are many ways to average the signal but the most important are linear exponential and peak hold average Averaging means that we calculate many FFTs during the time and average the frequency lines We can do linear averaging each FFT counts the same in the results exponential FFTs becomes less and less important with time and the peak hold only maximum results are stored and shown There is one more thing about the averaging loss of information When averaging i
77. display click on it and it will get a white border around it which shows that this graph is selected Channel Excitation 2 003 EPI The items which are displayed on each graph can be chosen from the right Response Pointimdex side transfer function list table with left click on channel TAE HE an 7 1 PRET a By MT a ii e for excitation scope and FFTs the excitation channels can be selected see example on left p AE A 053 MPS na gt e for response scope and for FRF transfer functions the response IA channels can be selected ASE WPA per aoe MPS E A EA A 058 MP10 3 NOTE screen display selection is limited to maximum 8 channels DeweFRF v6 5 User Guide v1 2 0 page 115 2007 DEWESott Measure Graph Display Display properties Display option Frequency response function hs A A ne MS sh i bf A PEUT hi MEET i d ral aT y et in For FRF we have several choices paa El e on the upper FRF display we can show coherence phase real or imaginary s Coherence D isplay display Real Imaginary The coherence is the ratio between vector and scalar sum of single FRF shots and shows how well the FRF shots are correlated to each other The coherence of 1 shows perfect correlation coherence of O shows no correlation When we select coherence and if we click on coherence curve the value of coherence in this point is displa
78. e For detailed information see FRF setup gt Point Maker 4 To set up Point Maker click the E icon Geometry is stored in unv Universal file format data file and can be imported from this in DeweFRFs FRF setup file with Import menu gt Geometry for information about Import Export Geometry see User Guide gt Data management gt Geometry Arrows are defined in Transfer function selector Channels assignation SUGGESTION because Geometry and Modal FRF Data are stored in same unv Universal format file it is strongly recommended to use separate filename for new or modified Geometry DeweFRF v6 5 User Guide v1 2 0 page 94 2007 DEWESoft Geometry window toolbar FRF Setup Geometry window Some tools are accessible on FRF Geometry window toolbar for explanation click on button OR A S FAP a le MANIPULATE with geometry e Pan e Zoom e Rotate e Point Maker SETTING FOR ANALYSE Scale and Speed see Analyse Geometry window DISPLAY SETTING e Arrow e Trace line e Nodes number All tools are accessible with press on appropriate button icon me Pan When this button is pressed we can left click and drag the mouse inside the geometry window to move the geometry on geometry window Even if rotate is chosen option we can pan with Shift click on geometry display EN Rotate When this button is pressed we can left click and drag the mouse inside the geometry window to rota
79. e recorder by channels on this display we have also feasibility to select certain range of stored data for calculation In one of the next steps of DeweFRF procedure we can recalculate whole range volume of stored data or only certain smaller range of these The selection of stored data for recalculation can be done in Ch setup From stored data procedure where there are some ways to select certain smaller range of whole volume stored data for recalculation on e with Time selector or The selection of this range is the primary goal of this procedure If we are to recalculate whole range of stored data no action in Ch setup after reloading data are needed and we can proceed with procedure for Offline Calculation The setup of the display as seen below depends on the display setup of Overview screen during acquisition of data either in Dewesoft or DeweFRF ox Time selector 7 ahi show Start show time Ch setup FAF setup Colousie ne white bordered rectangular a a indicate range of stored data stored data Fee Import Export pysben et f From madura File name f From sioned drie Fit ca start date and time of stored data Pg Lp pai MPS 2 iip 2 inf iila Display stored data by channels 5 05 Mii DeweFRF v6 5 User Guide v1 2 0 page 134 2007 DEWESoft Time overview bar Offline calculation Channel setup Time selector show Start show time and Shown time
80. e shakers are driven by either analog output or by external DeweFRF v6 5 User Guide v1 2 0 page 74 2007 DEWESoft Function Generator FRF Channel Setup Analog out shaker system The force is induced in the structure and the response of the structure is measured by the accelerometers or another vibration transducers shaker Analog output j Force E Vibration measurement In Analog out tab of DeweFRF Channel Setup Screen can be set for particular operation mode e Frequency setting Hz and Time setting sec for explanation click on operations mode name bellow e Control Options 18 x Fa CE Ma A F enamel E PTI 5001 Sterne bma cau Analog Hors MNT Er ee P re Sweep SE Burst Chip 7 DRA tii Start output i on slarteacg F Show inta channels l Reo E Dar E ua The function generator offers five different operation modes which are set for all analog output channels Fixed signals with a constant frequency Sweep gt Sweep frequency from Start frequency to End frequency Step sweep gt Sweep frequency with certain fixed frequencies Burst gt noise output Chirp gt sweep frequency with is shorter time and repeated after a defined time The amplitude will not rise from zero to full amplitude immediately but within a definable time This ensures that there are no jumps or glitches on the generated signal which is important to avoid i
81. eLines Trace Line 1 2 Trace Lire 1 1 0 2 3 0 3 d In the Geometry window the trace line display is also accordingly modified DeweFRF v6 5 User Guide v1 2 0 page 104 2007 DEWESoft Trace Lines FRF Setup Point Maker Delete trace line Deleting trace lines Point Maker can be accomplished in two ways 1 With deleting the trace line Using the left click we select the cell with the name of the trace line to be deleted Tracel mes Trace me 2 Trace ine 1 3 Trace ine In Point Maker tools _ Delete traceine can be chosen to delete selected trace line Trace line 2 above Point Maker PointMaker O O O lo x TraceLines Trace line 1 2 3 Delete all racelines Auto scale Save Cancel If in Point Maker tools nt Et is clicked ALL trace lines are deleted 2 With deleting the node With deleting the node for example Node 3 as described in the procedure Delete node leaves trace line 1 as Nodes TraceLines Objects Tracelines Trace line 1 e Trace line 2 z o Auto scale Save Cancel DeweFRF v6 5 User Guide v1 2 0 page 2007 DEWESoft 105 Trace Lines FRF Setup Point Maker and trace line 2 as 10 x Nodes Tracelines Objects ma dar Ta TraceLines Trace line 2 z Trace line 1 0 Delete haceine Delete all tracelines Auto scale Save Cancel ALL trace lines connected
82. ed Therefore the use of overlap is highly recommended 25 SE 66 6 overlap is the minimum to ensure same weight for each sample Fo For further reading please see Reference Guide Theory of frequency analysis DeweFRF v6 5 User Guide v1 2 0 page 90 2007 DEWESoft Impulse hammer excitation FRF Setup FRF property panel setting Several settings are set in FRF property panel gt FRF MENU for Impulse hammer excitation type e Calculation type e Response decay e Window type e Pretrigger e Excitation window length e Trigger level FRF MENU Calculation type Calculation type Free run Triggered Triggered acquisition is used if the excitation is impulse like with modal hammer chirp or plane ps burst Averaging mode The additional option common in averaging is to automatically reject the overloaded FRF In this case if any of the signals either excitation or response goes to overload this FRF will not be taken into the final averaged result but will be automatically rejected Window type Rectangular Hanning Hamming Flat top length Triangle Blackman Exponent dowr The window for excitation channels is automatically Rectangular with a predefined window P E RNE tered Excitation window length The window will have a factor of 1 for the defined percentage of values and a value of 0 for the rest of the signal This can reject the double hits on excita
83. ee Analyse for offline calculation is the same as for directly measurement see gt In the Analyse window you see all the measured data FRF result graph analysis tools and all the points which are measured geometry displays measured FRFs with different Display options the list of measured FRFs is the selector for the display these on the graph of mechanical structure whit nodes tracelines as well as local coordinate system for observation of the deflection of shapes with animating the points on the structure or to show the maximum deflection shapes Animation Max shape or Circle fit tools for export FRFs and information about the settings of the project used to take FRFs i Snake FRF tools icon or starts automatically When FRFs are stored the Analyse window can be started by clicking on when Confirm F9 button is pressed in Calculate procedure de A FX FAX E aAa fa an _ le Ch selup FAF setup Calculate le Delete Delete al drame Max shape Cucle M Tocipbosid UFF apit Info j S Measured FRF curves of List of measured St selected channels excitation response points channels fi We AN gt FAF frequency ecole Lin T DeweFRF v6 5 User Guide v1 2 0 page 145 2007 DEWESoft DeweFRF software interface File Import Export System I J PD Do wey gt a Ch setup FRF setup Measure Analyse After start DeweFRF basic screen is displayed e In
84. een in Analog out tab DeweFRF v6 5 User Guide v1 2 0 page 80 2007 DEWESoft Channel setup FRF Channel Setup Analog out Press the Setup button in SETUP column to enter the setup screen for each channel for explanation click on field of interest Channel setup for channel 0 LZ x General settings gt Channel name Use this channel as signal oup Il Units Waveform Noise Color Amplitude volts Min value ETA Mas value FEET 2 One period preview Offset volts io ov toy Phase degrees Additional Channel setting for Noise and Arbitrary The upper left area of the analog output channel setup screen contains General setting e the base channel information Channel name measurement value Unit and Color Like in the analog input setup screen e the Min value and Max value fields can be used to set a minimum and maximum display value The upper right area contains two elements of Signal setting e the signal usage selection in Use this channel output as e the Waveform type The Waveform drop down selection has a direct influence on the settings displayed in the lower right area All generated channels themselves are available as DeweFRF virtual channels Also amplitudes offsets and phase angles are available as channels so they can be put in any visual control to monitor the frequency generator or they can be used in math channel for sim
85. esp F11 The Measure tool bar items provides a few basic functions for e resetting measurements Reset F5 to delete all the measurements e rejecting last measurement Reject last F6 to delete only the last measurement from the result e stopping the measurement Stop which can be restarted by pressing the Measure e when the data is correctly calculated FRFs can be taken by pressing Confirm F9 button If the impulse excitation is chosen make hits to acquire data Number of averages are shown on the right side with overload indicator and there are also some controls to monitor hits Reset average will reset number of averages to zero and Reject last hit will subtract last measurement from the result If more channels are to be measured go back to the FRF setup change the point indexes do another measurement and Confirm button will add it to all measurement result For detailed information see User Guide Measure DeweFRF v6 5 Tutorials v1 2 0 page 16 2007 DEWESoft Four step tutorial Analyse When FRFs are stored the Analyse window can be started by clicking on the nabse FRF tools icon or it starts automatically when Stop button is pressed in Measure tool EC O OOOO joix Ele import Export System Analysis toolbar Ge bi em BE be BA ACA D Um Ch setup FRF setup Mears Analyse Delete Delete al Aremaa Maa shapa Cicle ft To chphosd UFF myi Info Pa ae e JE BJ j u
86. essed in Calculate procedure x import Expert System Ge Lu ee EE Lx MX A A a a Ch celup FAF setup Cacusis naet Delete Delete al Arte Mas shape Cycle M To chpbosid UFF esporl Info E e E Ba i List of measured excitation response points channels EE rat Ru af EI JE r I au a 1 Bul Pal u i a i i ERE Ge F Bi FRE amples ais Leg F FAF Treno pala Lin Li In the Analyse window you see all the measured data FRF result graph and all the points which are measured geometry DeweFRF v6 5 Tutorials v1 2 0 page 25 2007 DEWESoft Calculation tutorial Analyse The FRF Analysis tool bar items Ex Ak AO 2 Delete Delete all Animate Mas shape Circle fit To clipboard UFF export i Info provides a few basic functions e When FRFs are stored the animation and shapes can be displayed for chosen geometry with pressing on Animation Analyse tool The frequency of animation can be chosen with clicking on the graph and the curves which are displayed can be chosen from the list with Shift click or point and drag with the mouse e Max shape show maximal deformation of shape e Circle fit calculation also Analyse tool is provided to quickly validate the results and calculate the damping of the system Measured data Measured FRF curves of channels can be 1 EXPORTED to the universal files with UFF expo
87. etup The only thing we can t choose is the frequency span because it is defined by the sampling rate of time domain data which is loaded In our example select for example 400 lines choose H1 Blackman window and 50 overlap DeweFRF v6 5 Tutorials v1 2 0 2007 DEWESOft page 23 Calculation tutorial Calculate 2 3 Calculate ted The Calculate can be started by clicking the e FRF tool icon The Ch setup selected range of the data file will be immediately recalculated with parameters chosen in FRF setup gt DeweFRf E 10 x e HE A Ag Ch abu FRF i Candie Arapa Rest FA Frresci Emi PH Shp Contes FA ARA Aft i e T ME E J IE aN AS AN IRR RERRRER E Puis j wt sb Lx prit LE A a ps MENA Te 1 il i i FRF parameters can be furthermore adjusted except Frequency span can not be set and FRFs can be recalculated by pressing again Calculate In our case you can play with settings to optimize the results Choose different window for example Rectangular to see how important it is to use the correct window For detailed information see User Guide Offline calculation DeweFRF v6 5 Tutorials v1 2 0 page 24 2007 DEWESoft Calculation tutorial Analyse When FRFs are stored the Analyse window can be started by clicking on FRF tools icon or it starts automatically when Confirm F9 button is pr
88. finished This requires a defined cycle number for output in the operation mode settings DeweFRF v6 5 User Guide v1 2 0 page 78 2007 DEWESoft Activating outputs On Off FRF Channel Setup Analog out This column displays the state of the channel Unused gt disabled no signal output Used gt active signal output Click on the button to activate or deactivate channels If it reads USED then it will be available In Value column you can set all analog output channels signals individually for each channel Waveform type The waveform type can be set individually for each channel e Sine e Triangular e Rectangular e Saw e Noise e Arbitrary Also Amplitude Offset and Phase can be set individually for each channel as well If you need precise entries simply click in the numeric field in appropriate column and enter the desired value directly with your keyboard Amplitude offset and phase can be set also in Channel setup with tup l Ok slider or enter the desired value directly E Le x DeweFRF v6 5 User Guide v1 2 0 page 79 2007 DEWESoft Waveform type FRF Channel Setup Analog out In DeweFRF software the waveform types are SINEWAVE TRIANGLE RECTANGLE SAW NOISE ARBITRARY Waveform types can be set in e Waveform of Value column in Analog out tab or e Signal setting of analog output Channel setup scr
89. ge 53 2007 DEWESoft Data management Time data 2 5 Time data In Time data dsd Dewesoft data file measured time domain data is stored Import Time data gt From stored data a ae aa gt De ci Es Ey PUE Lt Esper 2 gt Ch setup FAF setup Calculate Analyse From stored data File path C DewetromiProgramiDEWESoftB34 Loading Store time data measured data can be done by selecting From stored data choice on Ch setup window After pressing on button Choose Dewesoft file window is displayed for loading existing measured data from dsd data file Ajma Store Timed ced ErmerSurst Steam dsd EmerBurst_Trig dad If we confirm desired file in list with Open we get a little bit different Ch setup window DeweFRF v6 5 User Guide v1 2 0 page 54 2007 DEWESoft Data management Time data Export Time data Store time data to save measured data during extensive calculations to 454 data Saving measured data can be done by selecting Store time data CCE a aN Fie greedy ost Do vou ment to overerte the Ge button on Ch setup window After pressing this button we get Warning screen for overwriting file stated in the field File name By pressing Yes we overwrite this file by pressing No File name fes i File path CiDeseton Program DEWESONAS App Dewe FRF Data data was not stored and we return to Ch setup window In File name we can enter
90. hannel frequency analysis Averaging how to enhance the results 2 7 Representation of different signals in the FFT For now we have only seen how the sine waves looks like in the FFT but let s observe how other types of the signals look like 1 Triangle rectangular All signals that are periodic with time but are not pure sine waves produces base harmonic component as well as additional higher harmonics More the signal is not like sinus higher the harmonics are 15 15 05 j as i AS l g q mA of oA if i 2 30 50 89 4100 i f He Picture 21 TIME DOMAIN SQUARE WAVE Picture 22 FREQUENCY DOMAIN SQUARE WAVE 2 Impulse Impulse is quite interesting thing It cannot be described with sum of sine waves Or in different words it is shown equally on all of the frequency lines That s the reason why we use it as the basic excitation principle to get frequency responses of the system The other ones are swept sine and noise but this is already a part of another story dual channel frequency analysis 05 4 0 001 an 0 0 07 004 0 08 0 08 01 0 0001 Els f HE Picture 23 TIME DOMAIN IMPULSE Picture 24 FREQUENCY DOMAIN IMPULSE DeweFRF v6 5 Reference Guide v1 2 0 page 169 2007 DEWESoft Theory of single channel frequency analysis Representation of different signals in the FFT 3 White noise The theory says that white noise consists of all frequencies That s why the
91. he FRF Analysis tool bar has additional possibility for SISO measure model Single FRFs which have inadequate results can be removed and measured again by pressing Re measure button RC fox Fe Impon Export System oy H ends OW EE aar PT E ANA Po ue a CA sebg FFF stup Mentira Anak Delete Dekie al Fis meneurs TO Poel Cda ft Tocipbosrd LFF export Inka In this animation it is clearly seen that point the point 7 is not measured perfectly We have to choose the faulty FRF from the list on the left side and choose Re measure to go back to Measure mode After taking new measurement on point 7 we press Confirm to add this measurement to the results The incorrect measurement will be replaced with the new one DeweFRF v6 5 Tutorials v1 2 0 page 35 2007 DEWESoft SISO Single 1 0 modal analysis tutorial Analyse BC eee 10 x Ple Impon Export System LT pas basai mH Lx HR ED E tars AG EL STE Ch saup FFFesuip pentire Anana Cisteis Deke ol Fiersa AL Fil Gide Toclphcerd LFF exp n hia RIRE PAPER la eel FRE Co Phase FA rc vom bu The Animation helps us to immediately see the quality of measurement results Each natural frequency can be further examined with Circle fit For modes which are spaced far from each other circle fit will yield quite good idea of the exact natural frequency and the structural damping of the certain modes RE eee lo x Ale Import Export System Le Eur SHE Ex HUR pS rs Ao E
92. he excitation point is moved it is important to measure the mobility point the same point of excitation and response that the animation can be shown correctly 2 Continuous measurement A single or multiple shakers are driven by either analog output of DeweFRF see Channel setup or by external shaker system The force is induced in the structure and the response of the structure is measured back by the accelerometers or another vibration transducers DeweFRF v6 5 User Guide v1 2 0 page 118 2007 DEWESoft Measure Measurement If the shaker is used for excitation of structures the system has the following configuration Shaker Analog output Fore Le ae age gt i MA Y li re Vibration measurement Then the measurement can be started by pressing Measure If the time data is loaded the menu item button is called Calculate if the data is stored parameters can be adjusted and FRFs can be recalculated by pressing again Calculate Transfer curve selector will show chosen excitation and response channels in gray color When the data is correctly calculated FRFs can be taken by pressing Confirm button If more channels are to be measured go back to the FRF setup change the point indexes do another measurement and Confirm button will add it to all measurement result 5 3 Measure tools The Measure tool bar in upper part of screen hold some action button for basic operation Measure t
93. he point 2 is chosen because we don t want to load too much the structure with the mass of the sensor If it would be on point 8 it would affect more the natural frequency of the beam In order to be successful we need to provide a good surface to place our item under the test Ideally the structure should be free in the space not to have a contact with any other element Since we usually don t have a chance to do our modal testing in the orbit we have to make some compromises There are two ways of doing this first is to put the structure on some foam or light springs with as low natural frequencies as possible Second way is to tie the structure to the heavy structure with known natural frequencies far away from what we are interested in What helps in this case is that we can t really excite a big table with low force needed to excite the light beam as we have DeweFRF v6 5 Tutorials v1 2 0 page 31 2007 DEWESoft aa SISO Single I O modal analysis tutorial FRF setup Now we have to decide for the strategy of doing the test In general we could move the excitation points or points of measurement In the eyes of results there is no difference as long as we measure the mobility point But from the structure point of view it is far better to move the excitation point because with moving the response we would change the property of the beam with mass loading Natural frequencies would shift a little and we would never get as good resu
94. hrenheit enter 1 8 in the top box and 32 below There are two ways of entering the value Sca e Scale k factor example above k 0 02 N mV by two points Scale factor is the factor which defines how to scale the electrical signal to deduce the physical values e Sensitivity same example k 50 mV N Sensitivity is the factor which is usually used in sensor calibration sheets and defines the electrical output per physical quantity measured by the sensor Use the Set Zero button in the main setup to conveniently offset the signal to force it to zero when it is not exactly at that value but should be due only to small sensor offsets and perhaps long cable lengths causing capacitive coupling and or line loss DeweFRF v6 5 User Guide v1 2 0 page 68 2007 DEWESoft Channel Setup FRF Channel Setup Analog The ability to quickly calibrate directly to DC and AC signal sources is a great advantage of DEWE software and will save you much time and ensure better and more reliable data recording long into the future In 2 point calibration there are two other sets of buttons that will allow you to perform a more accurate calibration when you have access to a known signal source or load Let s say that we have a load sensor that we want to calibrate to a known load We want to enter two points say zero 0 kg as our first point and twenty five 25 kg as our known second point The first thi
95. ime data WARNING because Geometry and Modal FRF Data is stored in same unv Universal format file is strongly recommended to use different filename for this new or modified data file Geometry Modal FRF Data DeweFRF v6 5 User Guide v1 2 0 page 45 2007 DEWESoft Data management Project file 2 1 Project file In Project dfs Dewesoft FRF project file Channel setup data FRF Setup data and Geometry data are stored does not include time or FRFs measured data New project We can start with a new project by selecting a New project and Channel setup screen is displayed New geometry File menu New project CS Open project E Save project Save project as You can define all new Project data Channel setup data FRF Setup data and Geometry data Don t forget to save Project after making a setup Open project gt We can directly import an existing project by selecting File menu gt Open project oo New project CE geometry or by click on Open project i save project File menu gt name of recent project OR Save project as ee a by this option project opens automatically 1 Ajmar 2 Palicab_Proj_Test By selecting the first option the standard Open window is displayed to load existing Project project from dfs Dewesoft FRF project data file My Documents TE Le My Computer sr Moja mre a
96. information about Theory of frequency analysis and H1 H2 and Hv calculation algorithms Background information For details on using this help about DeweFRF software see also gt Getting help About DeweFRF software FRF is abbreviation for Frequency Response Function which is the base for working with DeweFRF Modal analysis is a procedure of determining system characteristics of e mechanical systems this would be a response of a certain mechanical construction when a force is applied and e electrical systems this would be a response of an electrical system for example an amplifier DeweFRF modal analysis software is software that helps to generate input signal excitation to system to measure systems response and analyse system characteristics see Basis of work with DeweFRFs for getting more information about DeweFRF software DeweFRF software can be used with recommended system hardware and software gt see System requirements DeweFRF v6 5 Welcome to DeweFRF v1 2 0 page 2 O 2007 DEWESOft Getting help Getting help This help is designed to be used on screen It is extensively cross linked so that you can find more relevant information to any subject from any location If you prefer reading printed manuals then a PDF version of the entire help is available This may be useful as a reference but you will probably find that the active hyperlinks cross references and active index make
97. l Measured FRF curves List of measured of selected channels excitation response points channels Hi ele H J 7 p r L i i Bi me Es Ri Es Ri Ri Ei Ri J sa r ir pa F f b FAF Chapin F FH 7 FAF amplia nous F FAF r quiresy ea win T In the Analyse window you see all the measured data FRF result graph and all the points which are measured geometry DeweFRF v6 5 Tutorials v1 2 0 page 17 2007 DEWESoft Four step tutorial Analyse Analysis tools The FRF Analysis tool bar items Lx A AD a az Y Delete Delete all Animate Mas shape Circle fit To clipboard UFF export Info provides a few basic functions e When FRFs are stored the animation and shapes can be displayed for chosen geometry with pressing on Animation Analyse tool icon The frequency of animation can be chosen with clicking on the graph and the curves which are displayed can be chosen from the list with Shift click or point and drag with the mouse e Max shape show maximal deformation of shape e Circle fit calculation also Analyse tool is provided to quickly validate the results and calculate the damping of the system Measured data Measured FRF curves of channels can be 1 EXPORTED to the universalfiles with UFF export menu as Modal FRF data Coherence Excitation data or All data 2 Copied To clipboard and from this to others SW For detailed information see User Gui
98. l Setup Analog out To paste values from clipboard or load values from a file select the Points tab and right click This function can also be used to Copy to clipboard or Save to file Amplitude Scaling of the waveform can be done in three ways Wavelorm e Direct inserted values are taken directly and can never be changed Arbitrary Signal Ponts e Auto inserted values are scaled with the amplitude value like the other waveforms even online Sesing sigo y e Custom inserted values are scaled by an scaling factor This factor is not changeable during the signal output Back to Analog out channel list Back to Function Generator DeweFRF v6 5 User Guide v1 2 0 page 85 2007 DEWESoft FRF Setup 4 FRF Setup In FRF Point amp Geometry setup FRF setup we can define DeweFRF modal analysis software and applied mechanical structure FRF setup is relevant for measuring directly while acquiring data with continuous or impulse excitation or for offline calculation see Measure methods FRF property frequency span number of lines calculation method and FRF Calculation type free run or triggered acquisition with all of its properties Channels assignment point index of excitation and response channels adding removing excitations or responses with help of FRF setup tools Geometry of mechanical structure with nodes tracelines as well as global coordinate systems More about Import Ex
99. l available channels MDAG ACC 2600 m 300 k MDAQ ACC IBAA eit ON le AMPLIFIER 003 Set PowerOnDefault Reset PowerOnDefault DACP only DAOQP MDAQ modules Clear not found modules Fill Zero Set t DeweFRF v6 5 User Guide v1 2 0 2007 DEWESoft page 61 Physical values FRF Channel Setup Analog Contains a dynamic representation of this input channel as well as the PHYSICAL VALUES F N units of measurement and description and the scale 200 a g T ET All this can be set in Channel setup column which can be reached by double click UM on channel cell in this column When the input signal exceeds the possible range UN a red indicator OVL overload will be displayed AE E LA PHYSICAL VALUES um 18 uM 1E4 Zz Sites U M 1E4 al 1E4 If this happens check your sensor and or select another input range in Channel setup In the case of multi channel PAD modules like the PAD V8 P PAD TH8P et al this field will be divided into smaller boxes each containing a digital representation of your inputs PAD THe ec This is a button that you can click to perform a mathematical zeroing of this input to offset small variations in the zero position of the input Press the left mouse button to activate zeroing and the right mouse button to deactivate it reset to default input range E The Auto 4 button is also activ
100. l v1 2 0 Contents IV MA A o nn nr si 129 SR O tam ucnenametiunetas 130 EDO ERRES O nn A 131 A SN Ne 132 Offline calculation Afnani aaa aa man 133 Channel SOU diia A A a aTa 134 MS OV MINE adidas 135 Display Orstored data mad 138 ERE SOTO He en de IR Re A a E 142 Calculate jg qj qj Hire rene nets ent 143 A AISES O Riola 145 DeweFRF software interface comcccnnnennnennnonacononnnnrnnannnnrnannnnrrnarrnnrnnnrnnnrnnnrnnnrnanennnens 146 MES LE nina de ent Ne a RE 147 Part IV Reference Guide 149 DeweFRF System setting 150 General selling een Duran tot a 150 Hardware S elUD Aerie ne 150 Analog II o A aE PT Tean 151 Hardware arnverinstallatiOn gt ARR Er ai ori 152 Activate DEWETRONIMOQUSS ida 152 DEMO MOJE CC de a a a ee a 153 REAL PROFR MOAS ML in oh Dome 154 CHAN OR nn nn 156 Analbg QUESBLID un rase en ed eme Dead els 157 Mathematic Unions nieyssasndisatpt ahmed nant teens 157 CR ae N 158 Theory of single channel frequency analysis ccccccocccccnaninononcnnonananonnnnancncnnannnanannnnanos 159 What is frequency analysis OO Sienne finement ic 159 Theory OF frequency analysis isa dic 160 2007 DEWESOft DeweFRF 6 5 User manual v1 2 0 Contents V Properties of the Fourier transform nain ts tien De een net nee E 161 Where we can get in trouble ncoccccnnccnnnnoncncenannnnncnnnnnnnnnrrnnnrrnnnrrnarrnnarrnnn nena nnaman nnmnnn nnmnnn 163 How can we a
101. lect X or Z coordinate of the same node Nodes Tracelines Objects Node is clicked Point Maker Y To delete ALL the nodes at the same time in Point Maker tools Dekteallnodes button is clicked Nodes do not renumerate above right table shows node 2 is deleted All TraceLines attached to the deleted node are also deleted Navigation keys lt tothe previous cell in the same line in number one digit left and from first to the previous cell tothe next cell in the same line in number one digit right and from last to the next cell Tab tothe next cell from Z also to X of the next line Shift Tab tothe previous cell from X also to Z of previous line T up one cell in the same column up one node Y downone cell in the same column down one node Home to the X coordinate of the same node in number to leftmost digit and then to the X coordinate End to the Z coordinate of the same node in number to rightmost digit and then to the Z coordinate PgUp first node in the column PgDn lastnode in the column Enter selectthe entire number in the cell Backspace deleting the left digit in number while editing the coordinate or entire number when this is selected Delete deleting the right digit in number while editing the coordinate or entire number when this is selected DeweFRF v6 5 User Guide v1 2 0 page 101 2007 DEWESoft Trace Lines FRF Setup Point Maker Trace line is defined with
102. librate from average from average from RMS from RMS Depending on the pressed button s in this area different Input and Scaled values are represented on dynamic graph If you have an AC signal source you should press the red labeled AC RMS button below the graph to add the RMS values to the dynamic display On a dynamic graph your signal is represented e onthe left side the electrical units e on the right side is the scaled engineering units That way you can directly observe the effect of your calibration values In this command on graph you can change CALC ulations TIME and signal display frequencies of the selected values Predefined choices are e 0 1 second e 1 second DeweFRF v6 5 User Guide v1 2 0 page 70 2007 DEWESoft Channel Setup FRF Channel Setup Analog Depending on pressed button s in this area different Input and Scaled values are represent on dynamic graph When button Input and Scaled signal is represented on dynamic graph When button Input and Scaled signal is represented on dynamic graph is pressed AC RM value of your If you have an AC signal source you should press the AC RMS button When button Minimum Maximum value of your Input and Scaled signal is is pressed represented on dynamic graph Usually the and dar button are pressed and this way Average and Minimum Maximum values of your
103. lines between the nodes assigned to construction This is an on off switch button e Point number E e Trace line DeweFRF v6 5 User Guide v1 2 0 page 110 2007 DEWESoft Tools FRF Setup Point Maker Nodes tool Delete node Delete all nodes i Save Cancel Delete node Delete selected node e Delete all nodes Delete all nodes Nodes do not renumerate by Delete node All TraceLines attached to the deleted node are also deleted Common tools see above TraceLines tool Delete traceline Delete all tracelnes Save Cancel Delete traceline Delete selected traceline e Delete all tracelines Delete al tracelines Common tools see above DeweFRF v6 5 User Guide v1 2 0 page 111 2007 DEWESoft Measure Before trying to do the measurement let s notice that there are two ways Measure methods of making the FRFs measure In FRF Measure we can acquire frequency response data using applied hardware Measure is relevant to measuring directly live while Calculate is procedure for offline calculation in Ch setup selected acquiring data with continuous or impulse excitation and is range of the stored data will be immediately recalculated with represented in this chapter parameters selected in FRF setup gt see Offline calculation Property panel frequency span number of lines calculation method and FRF Calculation type free run or triggered acquisitio
104. log channel list DeweFRF v6 5 User Guide v1 2 0 page 63 2007 DEWESoft FRF Channel Setup Channel Setup Analog To calibrate any input just click the Setup button for that input eg for set channel 0 press Set ch 0 button This is a button that calls up the Channel setup dialog box for this input channel and this setup dialog will appear Channel setup for channel 0 General Channel name Units Color Sample rate divider Scaling First point Calibrate from average from RHS Min value Automatic Mas value Automatic by two points by function For explanation click on field of interest MDAQ ACC 5H 239400 Rew110 Range 10000 mV ha Lowpass filter Emm fe CP Voltage Current dm 8m current is valid for MDAQ ACC channels 7 Coupling DE f AC S Hz Input type MO40 Base SN 111111 Rew 103 Input value Scaled value Second point CCS equals joo Calibrate 7418 5 m 148 370 N from average 10000 m 200 N 2 oh from RHS FEC Average AC RMS Hin Z Max 10000 m 7663 3 m 200 H 153 265 H 126 8 mY 2 536 H Back to Analog channel list In this General part of Channel setup screen you can enter the Channel name the measurement value Units of measurement define Color display range Sample rate divider and Module selection for this channel Channel setup for channel D General Channel name
105. lso have the Auto scale y axis If we move with the mouse left to y coordinate of icon enlarge zoom in l icon contract zoom out x axis FRF graph the pointer change to 4 and we can by left click gt Auto scale y axis right click gt Full scale y axis 5 2 Measurement When we set the Property panel in fact in FRF setup Graph display and Transfer curve selector we can start the measurement e measure the FRFs directly while acquiring data and the e to Calculate offline from stored data see gt Offline calculation Directly measure the FRFs while acquiring data There are two methods to generate input signal excitation and also measurement impulse measurement input signal excitation is generated with modal hammer continuous measurement excitation with function generator or shaker 1 Impulse measurement Typical impulse measurement is Single input single output modal analysis SISO for details see SISO single I O modal analysis There we define two measurement channel one is excitation another one is response and help to get faster results When confirming the measurement either excitation hammer or response sensor has to be moved to the next point However it is advisable to always move the excitation point through the structure especially if it is a light structure otherwise the natural frequencies could change due to the mass loading effect from the sensor If t
106. lt as we would move the excitation Our first excitation point will be 1z since we have to start from beginning and our response point will be always 2z Now we can proceed with Measure DeweFRF v6 5 Tutorials v1 2 0 page 32 2007 DEWESoft SISO Single I O modal analysis tutorial Measure 3 3 Measure We position the modal hammer on point 1 and make the hits ojx Aie Import Export System ri He Ae Ex Aj gt Lu AA Snake Aerea FE epee level Ff Slag Cone Fo Med es FI M l reg EF Ch sebg FRE esp Resporni Pontina 17 Rasp de NE Pots spots av r When first point is measured we have several controls to continue the test like always we have Reset F5 to delete all the measurements Reject last F6 to delete only last measurement from the result if the hit was inadequate Stop to stop measurement which can be restarted by pressing the Measure when the data is correctly calculated FRFs can be taken by pressing Confirm F9 button On the right side of the screen where the list of measurement points is shown we can immediately see which points are currently valid If we define the number of hits the bar will be shown in red to notice that the measurement is finished DeweFRF v6 5 Tutorials v1 2 0 page 33 2007 DEWESoft SISO Single 1 0 modal analysis tutorial Measure lojx D alo x m ER Net ence FiO Met res F11 Je
107. ly it is possible to define the number of chirp Cycles n to output The time settings also contain Startup time ts and Fall time tf which defines the ramp at the beginning and the end of the chirp Sweep time t1 the chirp duration and the Hold time t2 between two chirps Analog Analog out Fixed Chip FREQUENCY Tea Hz 200 zet ATIRE rage Chirp mode is similar to burst except the short sine sweep instead of the noise Chirp better defines the frequency range than the burst Applications The chirp signal is used for spectral analysis of nonlinear systems With the Control Options Output rate and Start output condition are set for the analog output The Start output condition can be set either to F Stop measurement after finish e on start acq which means that the output starts with the data acquisition or e manual the signal output start can be started manually during the data acquisition The Output rate of the function generator is not related to the sampling rate and should be more than 10 times higher then the highest output frequency to avoid harmonic distortion If Show info channels is enabled the values of the parameter channels amplitude phase angle offset and frequency are additionally available as dedicated channels in the instrument views and mathematics If Stop measurement after finish is enabled the data acquisition will be stopped after the signal output has been
108. mouse cursor will change by little move it s appearance to EX Now move the mouse to the second point of your zoom window like here Release the mouse button and afterwards also the lt SHIFT gt key to zoom now into the selected window DeweF RF D x Ele Import Export System Ch setup FAFselup Calculate Anales Mccain File name Emets El From siored date Fe pat Cade Program DEVE Set Ape DRAE Dar TRIGGER MODE You can do this procedure as many times as required also in combination with the standard zoom in time axis There is difference to standard zoom that here is zoomed in both axis but only signals in zoom window signals of other graphs recorders is zoomed in only at time axis because there is only one time base To undo the last zoom simply right click once as already done in the standard zoom When you zoom in very deep you will see the really acquired data points marked with points the time between is a linear line DeweFRF v6 5 User Guide v1 2 0 page 141 2007 DEWESoft Offline calculation FRF setup 7 2 FRF setup In FRF Point amp Geometry setup FRF setup for offline calculation we can define DeweFRF modal analysis software The FRF setup can be selected by pressing FRF setup tool button In FRF setup we can define Geometry of mechanical structure with nodes tracelines as well as local coordinate systems Channels assignment excitation andresponses channel adding re
109. moving excitations or responses and changing pointindex FRF property number of lines calculation method and FRF Calculation type with all of its property About Import Export FRF setup data as Project data file see Data management When the Channel and FRF setup are done go tothe next step gt Calculate First it is recommended to load or define the geometry see Import Export Geometry FRF setup for offline calculation is the same as for directly measurement except Frequency span can be not set because it is defined by the sampling rate of time domain data which is loaded see FRF Setup E _joi x Fie Import Export System Ge e E A amp 1 e Ch setup FRE setup Calculate Anses Add Remove Add Remove oe em dx tx DeweFRF v6 5 User Guide v1 2 0 page 142 O 2007 DEWESOft Offline calculation Calculate 7 3 Calculate eh The Calculate can be started by clicking the F4 FRF tool icon Calculate is procedure for offline calculation in Ch setup selected range of the stored data will be immediately recalculated with parameters which is selected in FRF setup Property panel number of lines calculation method and FRF Calculation type with all of its properties same as and in fact part of FRF setup see gt FRF property panel setting Graph display set Excitation scope excitation FFT current and averaged the response scope and the freque
110. mpact shocks to the system under test DeweFRF v6 5 User Guide v1 2 0 page 75 2007 DEWESoft Function Generator FRF Channel Setup Analog out Fixed Fixed mode outputs the selected signals with a constant Frequency f1 Output frequency is the same for all the channels and is defined in the setup Analog Analog out Fixed Sweep Step sweep Burst Chirp a It is also possible to define a number of output cycles if the Cycles n checkbox is enabled otherwise the output is continuous The output frequency is the same for all selected channels If Allow live frequency change is enabled it is possible to vary the signal frequency during the output within selected frequency range Min frequency and Max frequency To avoid jumps in the signal a Startup time ts and a Fall time tf at the beginning and the end of the signal output can be set Applications fixed mode is used if a defined waveform should be output without changing the frequency or amplitude automatically Such function generator is valuable in laboratory testing of electronic circuits power amplifiers filters and so on Also it provides a great base for calibration procedures Multiple channels ensure a great chance to test delays and phase errors Sweep A sweep is defined by a Start freq f1 a End freq HZ f2 and a Sweep time t1 Additionally the Frequency change of the sweep can be either linear or logarithmic to provi
111. n with all of its properties same as and in fact part of FRF setup see FRF property panel setting Graph display set Excitation scope excitation FFT current and averaged the response scope and the frequency response function display Transfer curve selector transfer function list selector whatis shown on selected graph information about the amplitudes number of taken averages information about lasttrigger Measure measure performing Measure tools help to manage and control measure About Import Export measured data as Modal FRF data see User Guide Data management When the Channel FRF setup and Measure are done gotothe next step gt Analyse 299 The Measure can be started by clicking the _ sawe FRF tools icon for explanation click on field of interest A Ei l Resat F5 Rejec last Fe Stop The measurement consist of three major parts of the screen property panel graph display and transfer curve selector The property panel is the same as in FRF setup see User Guide FRF property panel setting DeweFRF v6 5 User Guide v1 2 0 page 112 2007 DEWESoft Measure Transfer curve selector The right side shows some information about the acquisition procedure It displays the information about ast trigger shot if it s ok it is green in case of overload it is red The number on the right side shows the number of taken averages Channel Excitation Response Pointingex
112. n and response channels When the excitation and responses are selected the table shows all the transfer functions which will be calculated Add excitation and response channels By pressing the 4 Add excitation button on the Channel Excitation 001 Ref Sinu a FRF toolbar we add the excitation channels Response Point index li 1X Me Pi d Hix mente ERY ote Ax rixe DeweFRF v6 5 User Guide v1 2 0 page 92 2007 DEWESoft FRF Setup Transfer function selector E By pressing the Add response button on the See Excitation FRF toolbar we add response channels Response Point index Het A e F vv Define the channels Then we can define the channels by selecting them from the channel list for each excitation and response Point index The point index can be directly obtained from the channel name if the correct convention is used see Channel naming section in Channel setup or it can be written in by hand by pressing the first column in form of 1X first the point index then the direction x y or Z and finally the sign or Arrow With direction and sign of point index is also defined arrow in this point When in the Geometry window of FRF Setup Display arrow switch is On the arrows display color is yellow for excitation green for response Single input single output modal analysis SISO In the FRF setu
113. n be deleted by clicking the Dass icon of Analyse tool bar All FRFs are deleted by clicking the Delete al icon After pressing this button we get the following Warning screen warra x AN eee ee ao to delete all analysis data By pressing Yes we delete all analysis data by pressing Cancel FRFs are not deleted Lema DeweFRF v6 5 User Guide v1 2 0 page 121 2007 DEWESoft Analyse FRF graph Central part of Analyse screen displays graph with measured FRFs which are selected in Tronster curvo By selecting E default the mouse moved over the graph will show cursor values for nearest point in channel color To do any analysis Animation Max shape or Circle fit the mode has to be chosen by clicking on the FRF graph A white vertical line will appear indicating the chosen frequency We can set display properties of graph in two ways Display properties Display option In left bottom part of Analyse screen we have several choices for FRFs Display e onthe FRF display we can show coherence phase real imaginary or br FRE Deppiar MIF Significance display Phare FRE erobtess sosie The coherence is the ratio between vector and scalar sum of single FRF Leg sal shots and shows how well the FRF shots are correlated to each other The TE Ez coherence of 1 shows perfect correlation coherence of O shows no correlation FRF amplitude scale Lo When we select coherence an
114. n the direction x y or z and at last the sign or e 10 1 convention as the channel description the second line of the name where the first number is again the node index followed by underscore an open bracket then the sign and the direction 1 is x 2 is y and 3 is z and 1 is x 2 is y and 3 is z and at last the closing bracket If any of above conventions is used point indexes directions and signs will be automatically assigned as soon as the channels will be used for measurement For detailed information see User Guide Channel Setup DeweFRF v6 5 Tutorials v1 2 0 page 10 2007 DEWESoft Four step tutorial Channel Setup Analog output channel setting LE Ch setup Analog out Fined Swe Sweep Burst Chirp Eneida Show irio channels Sweep ime nytt ioioiripirisia Fraquer Change finger El Stop measurement her tush i y E afe ee e efe eg a ii E E E E a With analog output setup we define excitation signals Few basic forms of excitation signals are useful for modal testing filtered noise sine sweep burst or chirp The output rate of the function generator is not related to the sampling rate and should be more than 10 times higher then the highest output frequency to avoid harmonic distortion Basic forms of excitation signals upper and lower frequency limi
115. nal beep when acquiring trigger by checking unchecking Beep on trigger 1 2 Hardware setup The hardware setup screen is same in all DEWE software When you first run DeweFRF it does not know which hardware you intend to use it with so Analog HW Device determine what we must set first Depending on hardware you can running Dewe FRF software on a computer e that does not have an A D card in DEMO mode or e with DEWE ORION 1624 most National Instruments cards most Data Translation cards most Spectrum and Microstar s DAP boards in PROF REAL mode for DEWETRON modules you can activate this modules which are determined in System menu gt Hardware setup gt tab After installing software you can for easy license handling of software and options install licence key Licensing DeweFRF v6 5 Reference Guide v1 2 0 page 150 2007 DEWESoft DeweFRF System setting Hardware setup Grouping completely independent each group can have different number of channels and start at any channel number required On this screen is also available Channel for high channel count applications The grouping can be done In Hardware setup is also available Math for activated mathematic functions Anal t sl an analog output for National Instruments M series boards Li asii for easy license handling of software and options Analo Card setup o When you choose Hardware setup in System menu initi
116. nce on the settings displayed in the lower right area Waveform Mose Sine Triangular Rectangular Saw Nose DeweFRF v6 5 User Guide v1 2 0 page 82 2007 DEWESoft Channel setup FRF Channel Setup Analog out Additional signal setting For Arbitrary type of waveform there are sliders and numeric fields in Signal setting tab additional is also tab Points for this signal setting For Noise type of waveform bellow the sliders there is also an additional Filter signal setting see also gt Noise Additional settings see also gt Arbitrary Additional settings In addition to the base channel settings the Noise waveform type offers a Filter selection Select between the filter types e None no filter is used the output signal is white noise e Pink a filter is used to obtain pink noise e Low pass define a low pass filter Sa Low p E EE zl ME EAT prototype Butterworth Chebysev or Bessel Order 1 to 10 FHigh Hz high frequency can be set define a band pass filter Order 1 to 10 oe eat prototype Butterworth Chebysev or Bessel Bessel Low pass Band pass High FHigh Hz and low frequency FLow Hz can be set For noise excitation it is common to define the upper and lower frequency limit The lower limit prevents DC excitation and upper limit prevents too high frequency noise which is higher than the bandwidth of the measurement
117. ncy response function display see Measure Graph display Transfer curve selector transfer function list selector what is shown on selected graph information about the amplitudes number oftaken averages information about lasttrigger see Measure Transfer curve selector Calculate tools help to manage and control calculate When the Channel FRF setup and Calculate are done go tothe next step Analyse Dewer RF i zigiz a a Ee Er m 7 Oh pepe FRE seo Cacuior Anies Retr Freche Ske Conte pH ty He peril s valk ui ds iid FRF parameters can be furthermore adjusted except Frequency span can be not set and FRFs can be recalculated by pressing again Calculate DeweFRF v6 5 User Guide v1 2 0 page 143 2007 DEWESoft Offline calculation Calculate Calculate tools The Calculate tool bar in upper part of screen of the offline calculation has only one applied action button for basic operation e Confirm F9 e Reset F5 Reject last F6 Stop Calculate tools Reset F5 Fejet last FE Stop Confirma FS When the data is correctly calculated the currently measured FRFs are stored in calculation results and we getautomatically Analyse procedure Not applied in Calculate DeweFRF v6 5 User Guide v1 2 0 page 144 2007 DEWESott Offline calculation Analyse Analyse is procedure to analyzing measured data which are acquiring from offline calculation s
118. ne GEQMETRY of shape basis for animation in FREs Analyse DeweFRF v6 5 Tutorials v1 2 0 page 13 2007 DEWESoft oo Four step tutorial FRF Setup FRF property The property screen is the same as the Measure screen 1 You can see general FRF setup on the left part of this screen in upper part of FRF property panel where you can define frequency span of measurement number of lines in FRF and calculation method The frequency span defines the upper limit for calculation and the number of lines defines on how many segments this frequency span will be split In the example above the 500 Hz span is split in 200 lines resulting in 2 5 Hz frequency resolution Next the calculation method has to be chosen H1 is commonly used function H2 can be used only when the number of excitation matches the number of responses the Hv is the most advanced method which reduces noise on excitations and responses but takes more time to calculate 2 On the left part of this screen in lower part of FRF property panel you can define calculation method in FRF MENU and of its property to the set of free run or triggered acquisition There are two main types of excitation e continuous excitation with function generator or shaker If noise or sine sweep is used in the function generator the Free run is chosen as the calculation type We have to define the window because of leakage Hanning or Blackman might be a good choice Since some sam
119. ng the Tab key then the cursors automatically goes to the X coordinate of the next node Modes Tracelines Objects Mode E Y E When we select File menu New Geometry or when Delete all nodes the following table is created In order to enter a coordinate value the cell for the value must be left clicked and the value entered Input for X coordinate can also be initiated by double clicking the header of column Node X Y Z We select the coordinate to be entered by left clicking on the coordinate cell and entering the given value A value must be entered for all the coordinates of each Node even 0 Edit node The field ofthe coordinate we would like edit modify is selected by left clicking and entering the desired value In the example below this is the Y coordinate of node 2 Point Maker Modes TraceLines Objects If the entry of the Z coordinate is followed by pressing the Tab key then the cursors automatically goes to the X coordinate of the next node A value must be entered for all the coordinates of each Node even 0 DeweFRF v6 5 User Guide v1 2 0 page 100 2007 DEWESOft Nodes FRF Setup Point Maker Delete node By left clicking on the cell we select the coordinate of the point we In Point Maker tools for deleting a node the would like to delete In the example below we would like to delete Delete node node 2 so the Y coordinate of node 2 is selected we could also se
120. ng to do is simple enter those two values in these Now we need to apply the known zero 0 kg load When it stabilizes press boxes as shown the left most from average button and the software will sample the input for a short time average the values that it receives then calculate the Canal Fora required number for the upper left box First point Now apply the known 25 kg load let it stabilize and press the right most from average button DEWE software is now perfectly calibrated to your signal based on the known loads that you input Note in the screen picture above that DEWE software has automatically input the two values in the upper two boxes that it needed in order to achieve this calibration Ifyou have an AC signal source you should not use the from average buttons use the from RMS buttons instead Also press the red labeled RMS button below the graph to add the RMS values to the dynamic display DeweFRF v6 5 User Guide v1 2 0 page 69 2007 DEWESoft Channel Setup FRF Channel Setup Analog The bottom right portion of the dialog contains a dynamic representation of your signal the left side are the electrical units and the right side are the scaled engineering units so you can directly see the effect of your calibration values for explanation click on field of interest Scaling by two points by function First point Second point Calibrate Ca
121. niversal file format data file Export for saving new or modified measured data file we have two options 2 Dewe a EX Geometry E Fer data El Measurement setup ed rene Export menu gt Modal FRF data UFF export on Analyse toolbar gt FRF data here we have feasibilities for selecting another sort of data eg Coherence Excitation data All data In both case Save FRF data As window is displayed for saving new or modified measured data to unv Universal file format data file WARNING because Geometry and Modal FRF Data is stored in same unv Universal format file it is strongly recommended to use separate filename for new or modified Geometry For detailed information see User Guide gt Import Export DeweFRF v6 5 Tutorials v1 2 0 page 41 2007 DEWESoft Part User Guide 2007 DEWESoft DeweFRF v6 5 User manual v1 2 0 Welcome to the USER GUIDE of DeweFRF modal analysis software Before trying to setup the measurement let s notice that there are two methods ways of making the FRFs measurement Process of each FRF measure consist of four basic steps and is introduced in following flowchart as Project For explanation move mouse on area activity of interest and click FROM STORED DATA CHANNEL setup MEASURE fae Rey Ter BEA De ed otal a ca Malines Erka T 1 LT Benne GEUMETRY ANALYSE SHOW EXPORT FRF deta Ar mete WMax
122. not be valid If we have amplifiers which supports different ranges like MDAQ ACC we can choose ower ranges to make the measurements more precise Channel setup for channel 3 General A D opt Sensors Non programmable modules Channel name Medwe tepe calor Minvalue PUTA Max value MTC Somplerate cider ER Scaling by two points by function Input value ocaled value Scale k factor BY 222222 N a SRE VIN 0 0002 Y 0 1 N Oitset n factor 0 0001 Y 0 1 N o oN 0 0006 Y 0 3 N Set zero _Setzero 5 Y 22727277N TA sec Output k Input value n Average AC RMS Min Max Ok Cancel Acceleration sensor response Basically we do the same for the acceleration sensor The measurement unit in this case is acceleration in g which we enter in units entry field The sensitivity as we read from the calibration sheet is 99 3 mV g which corresponds to the 0 993 V g which we enter in sensitivity field Fes P TER Calibration Chart for a dpi DeltaTron Accelerometer erro K Type 4507 B 004 STA Serial No 10856 Bruel amp Kjeer Reference Sensitivity at 159 2 Hz w 1000 s 20 ms 24H 4 mA supply cumant and 22 C 16 13 mVWimk Frequency Range Amplitude 210 Phase 5 2 He to 5 kHz Mounted Resonance Frequency 18 KHz 5 _ 993 ne The 5 V measurement range corresponds to the 5 035 g DeweFRF v
123. ns to one of the 16 on the system itself DeweFRF v6 5 User Guide v1 2 0 page 58 2007 DEWESoft Input channel Slot FRF Channel Setup Analog This field has also a copy paste function When you click on a slot number a window will appear Example several channel e g 0 2 and 6 contain the same DEWE Module with the same sensor connected If you click now on slot 0 and select Copy the system will remember all the important c Er settings from channel 0 like amplifier type input and filter ranges units calibration and zero Copy settings Now click on slot 2 and select Paste this will copy all settings from channel 0 to channel 2 and so forth with other same module 4 nn re Paste to all But you can copy the settings also to a channel selection or to allthe channels Paste to selection ATTENTION This function is working only with amplifiers of the same type Channel names will not be copied _ Back to Analog channel list Back to Analog out channel list Input 0 is already active marked Used beside it Click on the input slot to activate them and the screen is displayed like this In this column there is a button that you click to toggle this input on off Used Unused If it says Used then it will be available Use the button to activate deactivate used channels To activate deactivate all channels at the same time Just click on the El icon and the following selection window appea
124. of stored data symbolic display of signals nier CHATS start date and time of stored data Stored data offers at the top of the screen a small bar Time overview bar with end date and time of stored data e symbolic display of signals in white bordered rectangular with yellow cursor as an overview of the whole stored data e start date and time of stored data e end date and time of stored data e Trigger switch and e Time selector Within the Time overview bar there is also a cursor available and as a standard it is located at the left side of white bordered rectangular If you look carefully at this area you will see a yellow vertical line and this is a cursor As you can see on picture bellow time scale on bottom of Display of stored data include is whole range stored data in our example from 0 sec 30 64 sec Selection range of stored data 1 Time selector When you click on the jp Time selector icon on the right side of the overview bar the following Time selector window will pop up on Ch setup From stored data screen below Time overview bar 5 x Chien FAF setup Calcuste name Mee File name E From stored data Fis pais Ces PQ DENE E ADO Dar AP Doe AMM MPA 32 15 9 eat A E Ja dl i k gt yA 1 hunt J k A f Al r LU E el Mi ha Fis I S b chi a LA Ly pt ha C1 6 ia ig Ms Lx rat jh CLOS ra ar pois rer pa ia La a he i a Ti Ha Me y ty x
125. on methods available H1 H2 and Hv Hi minimizes the noise on input and is quite commonly used procedure H2 minimizes the noise on output but can only be applied if the number of input and number of outputs are equal Hv tries to minimize the noise on input as well as the noise on output so it s the best procedure But it takes more calculation power than H1 For further reading please see Reference Guide Theory of frequency analysis Averaging mode The average type can be Linear Peak hold or Exponential Linear average means that each FRF will have equal weight in the final result Peak hold average will take the result for each individual frequency line where the excitation will be of the highest value With Exponential averaging the FRFs will have less weight with time When Exp average type is selected the slope defines the weight of the ast average DeweFRF v6 5 User Guide v1 2 0 page 88 2007 DEWESott Common FRF Setup FRF property panel setting Stop conditions Stop on overload will stop the measurement and the function generator if the input or rs BEN output channels will go over the limit of physical measurement range or the user defined range Stop after option will stop the measurement after a predefined number of averages User defined OVL range If we select to automatically stop on overload or to ignore overloaded trigger shots the user defined OVL range defines the limi
126. ools A A Ej ya E EB Reset FS Reject last FG Stop Conhrm F9 Mext exc FIO Next resp F11 Reset F5 Delete allthe measurement and will reset number of averages to zero Reject last F6 Rejecting last measurement to delete only last measurement from the result In case of bad hit with low coherence it s not necessary to start from beginning but we can rejectthe last average and keep all previous values Stop The measurementis stopped it can be restarted by pressing Measure button or Calculate if we are calculating from already stored data Confirm F9 When the data is correctly calculated the currently measured FRFs are stored in calculation results Extra SISO buttons There are two more buttons which appear only if just one excitation and response channels are defined and help to get faster results This is typical by Single input single output modal analysis SISO for details see SISO single I O modal analysis e Next exc F10 Confirms the measurement and moves the point index that excitation point is incremented by one This allows us to immediately measure next point on the structure e Next resp F10 Does the same as above Next exc but it will move to next response point However itis advisable to always move the excitation pointthrough the structure In Calculate procedure is this tool bar little different see Offline calculation DeweFRF v6 5 User Guide v1 2 0 page 119 2007 D
127. overview bar with white bordered box Time overview box Symbolic display of signals outside of this box is dimmed Within the Time overview box there is also a cursor available and as a standard it is located at the eft side of box If you look carefully at this area you will see a yellow vertical line and this is a cursor With mouse pointed on yellow cursor mouse cursor changes to and then you can drag this cursor within box At the same time move also yellow cursor relatively proportional in the Display of stored data DeweFRF v6 5 User Guide v1 2 0 page 136 2007 DEWESoft Time overview bar Offline calculation Channel setup In case of selecting only range of stored data on Time overview bar in Trigger switch TRIGGER A TEER HODE m HODE Lado if 1b 2005 1447 01 instead appear Whit press this switch we enlarge selection on initial whole range of stored data and Trigger switch return to gt We can select another stored data within the whole signal with movement Time overview box on Time overview bar but with same range of stored data You can move the selection window Time overview box in three ways e enter a new start time in the Start show time window as described above by this option we can also change size of range Show time e click on the selection window Time overview box and move it by mouse inix Ele Import Export System Ge Ch setup FAF setup Calvulale Analy
128. p only the starting points are defined Then we can define all the parameters for the testing bandwidth number of lines excitation type etc For details see DeweFRF Tutorial SISO single I O modal analysis DeweFRF v6 5 User Guide v1 2 0 page 93 2007 DEWESoft FRF Setup Geometry window 4 3 Geometry window In the Geometry window we can see the geometry nodes points of mechanical structure to which channels for excitation and response are assigned gt see also Transfer function selector as well as trace lines coordinate system and when entering arrow with indexes directions and signs will be shown It is very helpful to load the geometry to get a feeling where to locate excitation and response About Import Export Geometry data see User Guide Data management gt Geometry for explanation click on field of interest The main part of the geometry window shows GEOMETRY of construction with points nodes trace lines arrow and directions eT ar a a ae On left side of geometry display there a is symbolic picture D geometry setting in of GLOBAL COORDINATE SYSTEM ANALYSE procedure Geometry window TOOLBAR is divided in three parts 1 MANIPULATE with geometry 2 Geometry SETTING FOR ANALYSE procedure SCALE and SPEED not relevant for FRF setup 3 Geometry DISPLAY SETTING Geometry of mechanical structure for FRF testing is usually defined in Point Maker orin another appropriate softwar
129. ples are near to zero overlap has to be defined to get all samples in the final result 50 or 66 overlap is recommended If chirp or burst is chosen the Triggered calculation is used to acquire only bursts The response decay can be used is the structure damping is low to reduce amplitudes at the end of calculation window Another application could be measuring electrical transfer functions with direct function generator output e impulse excitation with modal hammer For the impulse acquisition select Triggered excitation Rectangular Window type is used for the output but the values beyond excitation window length settings are trimmed For responses exponent down is used with exponent decay as set It is not necessary to set the detailed setup of the FRF from the left side since this menu will be also shown in the Measure screen For detailed information see User Guide FRF Setup DeweFRF v6 5 Tutorials v1 2 0 page 14 2007 DEWESoft Four step tutorial FRF Setup Channels assignment After Channel setup is the next step is to define FRF parameters At first the channels are assigned as such that the first channel is excitation channel and the following channels is auto assigned to the responses However the excitation and responses can be changed in terms of adding and removing excitations responses with buttons on FRF toolbar changing point index always starting by index number like 12 direction X
130. plitude at resonances and anti resonances H2 algorithm H2 algorithm expects noise on input H2 algorithm tends to minimize the noise on input In the presence of noise it underestimates amplitude at resonances and anti resonances Vertical offset leas squares minimizes distance in x or y direction Hv algorithm Hv algorithm expects noise on input and output Hv algorithm tends to minimize the noise on input and output It is always bounded by H1 and H2 The only cut down is that because of it s complexity it uses a lot of computing power Perpendicular offset total leas squares minimize distance in x and y direction DeweFRF v6 5 Reference Guide v1 2 0 page 172 2007 DEWESoft H1 H2 and HV algorithms for calculation Comparison of given method If there is no noise present all three algorithms give the same results That is why everything that is possible should be done in order to eliminate noise on input and output DeweFRF v6 5 Reference Guide v1 2 0 page 173 2007 DEWESoft DeweFRF v6 5 User manual v1 2 0 Index Max shape tool 129 B Basis of work with DeweFRF 4 dfs file 45 C dsd file 45 Calculate dss file 45 fogs 1 unv file 45 Channel setup 56 Analog input 64 Analog output 73 A Analog HW Device setup 151 D Activate DEWETRON modules 152 Channel grouping 156 Data management 45 DEMO mode 153 Geometry 50 Hardware driver installation 152
131. port FRF setup data as Project data file see User Guide Data management When the Channel and FRF setup are done gotothe next step Measure Hs For entering FRF setup click the FRF setup icon for explanation click on field of interest DeweFRF Fiz t pra z ah EEN FRF property panel SE 1e E _ 3 i i Ch selup FRFseup Measure Anayse Add Remove Add Remove PE Pete FRF setup toolbar for add and remove excitations responses fe ps e Channel pons Ato ME Hague ar LEZ Y B Haima A 051 MPS Hisa Hire TRANSFER FUNCTION dead SELECTOR Hp Channels assignation Host and changing Point index of Excitation and Response channels Hi Te Stop canditiont a IF Le E RTL S Him Stop on ceci ya AAA Stop after as MOSS MP CE O Define GEQMETRY of shape RE on 2 basis for animation in ooo O FRFs Analyse Lu Meme DeweFRF v6 5 User Guide v1 2 0 page 86 2007 DEWESoft FRF Setup FRF property panel setting 4 1 FRF property panel setting Some settings are set in FRF property panel Common settings e Frequency span e Averaging mode e Number of lines e Stop conditions e Calculation method e User defined OVL range Continuous shaker excitation e Calculation type e Window type e Overlap Impulse hammer excitation e Calculation type e Response decay e Window type e Pretrigger
132. re than enough theory let s just say that this analysis reduces amount of calculations by rearranging the data The disadvantage is only that the data samples must be of length which is power of two like 256 512 1024 and so on Apart from that the result is practically the same as for the DFT 2 3 Properties of the Fourier transform Let s take a look on the typical FFT screen on picture 6 The maximum frequency of the FFT is half of the signal sampling frequency in this case the sample rate was 22000 samples sec but in the upper region the results are never reliable so the sampling result should be set to 2 SampleRate MaximumSig nalFrequence 2 1 25 1 25 is absolute minimum factor for getting right values also in the upper region of the FFT This is the equation other way around of famous Nyquist criteria which says that maximal signal frequency adequately presented in digitized wave is the half of sampling rate Ci T mee CON CON CO CN DU DU DE se mmm o r ma E OCR COR O CON CRU CN CN ON ON OU EN A ak BEF HTH Hmm HHH HF He a cid biai US Re 6 er I I I I I l l I l I I I I CH aa aa EEN I I I i I I I I l I I E I I Fr I I i l I i I I I I I I I A eee I I I L l l I I l I I Ls i a a j or as An PRA is a dd it oo oo ee ee ee ee ee ee Es gt oe lc El rn pi AA A A Lan
133. rs Select all Deselect all Now use either Selectall to activate or Deselectall to deactivate all channels The Store button is only visible when a channel is set to Used the default setting after activating the channel is storing E 2 When you press the button this channel will be still displayed and can be used for mathematics but it will not be stored This function has been added especially to avoid storage of unrequired data for example you need the data only for mathematics and store the math result Back to Analog channel list DeweFRF v6 5 User Guide v1 2 0 page 59 2007 DEWESoft Channel color C FRF Channel Setup Analog Simply click on the colored field of the desired channel to open the color selector Choose from any displayed color or create a user defined one Press OK to confirm the change or Cancel to keep current settings The color of the channel can also be changed on the Channel setup screen General part of e Analogi n channel see gt Analog Channel setup or e Analog out channel see gt Analog out Channel setup This color will carry through the text and graph representations of this channel throughout all DEWE software procedure screens Back to Analog channel list Back to Analog out channel list Free text field for naming this input channel SE Just click into the field and you c
134. rt menu as Modal FRF data Coherence Excitation data or All data 2 Copied To clipboard and from this to others SW For detailed information see User Guide Analyse Export FRFs About Import Export Measured data see Project management tutorial For detailed information see User Guide Analyse DeweFRF v6 5 Tutorials v1 2 0 page 26 2007 DEWESoft SISO Single I O modal analysis tutorial 3 SISO Single 1 0 modal analysis tutorial Although providing mathematics to calculate hundreds response channels and multiple excitations single input single output test is quite common for simple low cost modal testing It is a little bit different in the way that either excitation or response channel should be moved in order to measure all the points SISO gt Single Input Single Output There are four basic steps to do SISO modal analysis e Channel setup e FRF setup Measure Analyse 3 1 Channel setup In the channel setup we define exactly two measurement channel one is excitation another one is response It is helpful to load the geometry to get a feeling where to locate excitation and response Hammer The hammer is usually the excitation for single input single output modal analysis We have to enter the scaling factors for the hammer The modal hammer comes with calibration sheet which looks lik this _ _ICP IMPACT HAMMER Performance ENGLISH Optic Sensitivity 15
135. rview bar at the top of the recorder display shows always the current position within the signal You can also click on the marked area and move the marker this will also move the displayed signal You can do that action several times to see the information of real interest 2 Zoom in out button We can select another range of stored data within the whole signal also with zoom in MM or zoom out button on right side of each graph As there is only one time base available all graph are zoomed in or out together independent which button is selected You can do that action several times to zoom into the selected area step by step by each step is decrease of range about 1 25 prior range and is meaningless in what place cursor there is By first zoom out graph return to previous zoom range and after that step by step If we use before multiple zoom with button or measurement cursor in first step displayed range return to about 3 4 its whole range and after that step by step 3 Window zoom Additionally to the described method you can also zoom in both axis using the window zoom also known as boxed zoom because you open a box To do that place the mouse cursor at the first point normally the upper left corner of the area of DeweFRF v6 5 User Guide v1 2 0 page 140 2007 DEWESoft Display of stored data Offline calculation Channel setup interest press the lt SHIFT gt key and keep it pressed the
136. s Tracelines The column TraceLines is selected using the left click In this column the name for the trace line is entered DeweFRF v6 5 User Guide v1 2 0 2007 DEWESOft page 102 FRF Setup Trace Lines Point Maker The name for the trace line is also displayed in the header of the right column which also contains the first empty cell for the first node input Nodes TraceLines Objects TraceLines Trace Im Trace iin The cell for the node input is selected using the left click During the entry of the node the cell for the next node is created below Nodes Tracelines Objects TracelLmes Trace ines 1 Trace line 1 il The next cell of the node list is selected using the Tab key or left clicking At the same time the trace line is displayed in the Geometry window Point Maker Nodes TraceLines Objects TraceLines Trace line 1 Trace ine 1 1 2 3 l Delate traceline Delete all trac elines The name for the trace line is also displayed in the header of the right column which also contains the first empty cell for the first node input Nodes TraceLines Objects TraceLines Trace ln Trace lr During the input for the name of the trace line an empty cell for the entry of the next trace line is displayed in the left column We can select it by left clicking Nodes TraceLines Objects TraceLines Trace line Trace ines 1 Trace be
137. s no influence on the measured input range itself and can also be set to any other value in the displays Sample rate divider The Sample rate divider can be used to reduce the sample rate for each channel It offers different types of reduction Skip selected number of values Average selected number of values 4th 6th or 8th order Filter As a standard the number of values is set to 1 Sample rate divider Scaling Average x E Filter 4th by two points by function Filter Eth ESF acct eo Filter Sth DeweFRF v6 5 User Guide v1 2 0 page 65 2007 DEWESOft Channel Setup FRF Channel Setup Analog Module selection All boxes and fields at the top right of screen depend from the built in module If you have actual DEWE Modules DAQP or PAD series in this computer they will appear here and you can control their ranges and filters directly from this screen e you could select any non programmable DEWE Module and Module type combo box and Measure range will be shown on screen older DAQN series are supported making this software backwardly compatible with all modules that we have made e if a programmable module is installed in this slot the Module type combo box will be replaced with a Range selector and the Measure range will be replaced with a Lowpass Filter selector and other module specific fields are shown for details see A D Board Specifications Back to Analog channel list For explanation
138. s used with window functions we could loose some data due to the window multiplication effects Signal Windowing and averaging with 0 overlap Windowing and averaging with 50 overlap Picture 20 OVERLAPPING In picture 20 there is one example where the signal only consists of one pulse If we average the result use window function and we are unlucky signal will fall in region where the window sets the values to zero and in resulting FFT we will never see this pulse That s why there is a procedure called overlapping which overcomes this problem It no longer calculates averages one after another but takes some part of the time signal which is already calculated and uses it again for calculation There could be any number for overlap but usually there is 25 50 66 7 and 75 overlapping 50 overlapping means that the calculation will take half of the old data Now all data will be for sure shown in the resulting FFT With 66 7 and higher overlapping every sample in the time domain will count exactly the same in the frequency domain so if it s possible we should use this value for overlapping to get mathematical correct results By the way do you know what real time frequency analyzer means It means that it is able to calculate and show data with 66 7 or 50 in some literature overlapping and therefore has no data loss DeweFRF v6 5 Reference Guide v1 2 0 page 168 2007 DEWESoft Theory of single c
139. sd We can either use reload already stored data in Dewesoft or we can store dsd file in DeweFRF Next step gt FRF Setup from stored data Store time data To store time domain data in Dewe FRF first set all the channels which will be used during measurement in Analog and Analog out tab The measurement setup can also be imported from Dewesoft setup file see Project management tutorial for explanation click on field of interest Devret HF l x Liwe measurement DIRECTLY while ia H acquiring data Maximum sample rate allowable Ana a tt core Store data during expensive bared clack FRF data calculation and reload it recalculate and analyse it later SLOT Caer Eu el ALLER Fe Fi Per inal WALES TER ETE 10 MDAD ACOE CET uM Unuse E FE ner Se ch Oo 2600 mv 300k a o O o E CE MDAQ ACC BE UM Unused 5600 vf 300k MDAQ ACC a eu MDAQ ACC 2500 mi 300 k MDAQ ACC 2500 mv 300 k MDAG ACC ems 2500 mt 300k peas fi unused a nee Define and set all the channels which r MDAQ ACC will be used during measurement 00 mi 300 k MDAD Bare 1OW 300k ADA O Bare sit 10 300k AT ze 5 Zero After pressing _Store time data button on Ch setup screen we get Warning screen for overwriting file stated in the field File name In File name field of FRF Ch we can enter setup screen a ne
140. se From mesure hey e le From stored data E mots REEE DAA iDN 52 4040 MPA Ag 52 ji nn rune An ar A PR i pb pes tote wl i j pa I e simply use the cursor keys this will move the selection window each time by the half size of the window itself 051 MPS 3 13 fe 5 05 5 da i Selecting in reloaded triggered data files The reload of multiple trigger events within one file shows a different display on screen _ DEGO EE x Ede Import Export System Ch setup FRE setup Calculate Analyse ee From stored date Fie path E A TRIGGER To display each event separately just press the Me button and use the arrows to move forward and backward between the events select event DeweFRF v6 5 User Guide v1 2 0 page 137 2007 DEWESoft Time overview bar Offline calculation Channel setup Eje Import Export System Ch setup FAFselip Calculate Analia 7 From reuse File name 3 is From stored date Fie pat EaD Program DENE SA Ape Dire Pipes ll LENA M A j pe At FE q oe i D LAN NM Mat Belek eho eee nt LR D LE PES A BL F All other action and procedure is same as are described above 7 1 2 Display of stored data After selecting From stored data and entering required file in File name we reload stored data and get Ch setup From stored data window with Display of whole range stored data like bellow we have to move yellow cursor from beginning of
141. segment of data for reloading and recalculating in User Guide gt Offline calculation offline calculation Set frequency span maximum sample rate allowable About New Open Import Save Export Channel setup data see User Guide Data management When the Channel setup are done gotothe next step FRF setup weg For entering Channel setup select New Project from File menu or click the Er icon and For explanation click on area command of interest E linia a Live measurement Maxi al LE Et Import Export System DIRECTLY while ES ERE s Eo LA T acquiring data Ch setup FAF siup He pie Fr EE Luadestored Store data during expensive Beem clack FRF data calculation and reload it recalculate and go nears Robes BLOT our A jg l ALFERD 00 FHTECAL WALES PEA ETF E i L z FE E 3 ear Set ch 0 Define and set all the channels which will be used during measurement En Pi col 10 common Channel Setup Screen is displayed Displayed tabs in central part of screen depend on selection in System gt Hardware setup menu and consecutive on measurement mode PROF or DEMO Note For FRF analysis it is reasonable setting only Analog and Analog out in Hardware setup DeweFRF v6 5 User Guide v1 2 0 page 56 2007 DEWESoft FRF Channel Setup In this User guide we can get help about the Analog tab and Analog out tab in Analog out tab also Function generator can be
142. sheap Circle Tociiptosrd UFF export This guide also contains detailed information about Offline calculation reload calculate and analyse stored data DeweFRF software interface Data management DeweFRF have many ways to Import Export setups geometry and measured data DeweFRF v6 5 User Guide v1 2 0 page 2007 DEWESoft 43 Measure methods Measure methods Let s notice that DeweFRF software enables two methods ways of making the FRFs measurement e first way is to measure the FRFs directly while acquiring data and the e second way is to measure and calculate respectively offline from stored data From measure operation mode gt direct measurement In this mode FRFs measurement is done directly while acquiring data This is most Pere a commonly used operation mode and is selected by default and doesn t require any bape ae Anal additional action File name There are two main types of measurement depended on type of excitation continuous excitation with function generator or shaker impulse excitation with modalhammer From stored data operation mode gt offline calculation Another way for calculation is to load the Time data file The way to calculate is exactly the same except that the data is xport System i i Export Syste not acquired but loaded from file Ch setup FAF setup Calculate Analyse Loading stored FRFs data can be done on Ch setup windo
143. sic procedures Work with DeweFRF compose four basic procedure step 1 CHANNEL SETUP to set all the analog channels which will be used during measurement excitation and sensors 2 FRF POINT amp GEOMETRY SETUP to define geometry and nodes of mechanical structure assign points and setup parameters for calculation 3 MEASURE acquire frequency response dafa 4 ANALYSE animating shapes calculate damping and export data to UFF and clipboard DeweFRF v6 5 Welcome to DeweFRF v1 2 0 page 2007 DEWESoft System requirements 3 System requirements Standard application requirements To achieve a good performance for all standard applications we recommend the following hardware and software e WINDOWS 2000 XP 2 e Intel Pentium IIl 700 MHz processor or higher e 256 MB RAM or higher e Approx 40 MB free hard disk space for DEWE Software Additional 20 to 200 MB for drivers and post processing software packages e A D board for using real mode requires licence key for setup this hardware see Hardware setup We strongly recommend to run DeweFRF with Windows Administration rights otherwise file access or driver problems might occur 1 DeweFRF is not running under WINDOWS 95 98 ME NT4 operating systems High performance application requirements For all high performance applications like high speed video or high speed data acquisition we recommend the following hardware and software
144. t The lower limit prevents h frequency noise which is higher than the bandwidth of Start end frequency and sweep time are defined in the setup before generation In addition to this sweep can be either linear or logarithmic to provide more cycles at lower frequencies For this mode the rise fall and dead time is defined Bursts are useful in testing response ignal but in practice noise is usually used as the base generated signal Bursts are usually enhancements of the noise excitation for measuring transfer function With burst we eliminate the need of using the window of frequency analysis and therefore noise For this excitation it is common to define the DC excitation and upper limit prevents too hig the measurement sweep burst characteristics of the systems Within the burst we can choose to have any s eliminate the errors caused by window chirp Excitation is similar to burst except the short frequency range than the burst For detailed information see User Guide Channel Setup sine sweep instead of the noise Chirp better defines the DeweFRF v6 5 Tutorials v1 2 0 2007 DEWESoft page 11 Four step tutorial Channel Setup Frequency span Freq span AU The maximum allowable sample rate will vary according to which A D board you have installed and how many channels are activated for recording In the drop down list select the appropriate frequency span WARNING Set the sampling rate
145. t least try to avoid It cocccocccconcccnnncnnnnonnnccnnaronnnncnnarnnanrrnaronnnrrnnnrrnna remar rrnarrnnnnenanrenannns 165 Averaging how to enhance the results cconnccnnnccnccccnncnconcnonarenannnnaronnnnrnnn nena rrnnnrenarrnnarenanrrnannns 168 Representation of different Signals in the FFT ou ecceesesceeeeeeeeseeeeeeneeeeeneeeeeneseeeneeseeeeseneesennenes 169 Conclusi n Ci Aaa aos 171 H1 H2 and HV algorithms for calculation 172 Index 174 2007 DEWESOft Part Welcome to DeweFRF Welcome to DeweFRF DEWESoft FRF modal analysis software that radically simplifies the analyse and determination of system characteristics As you would expect from a fair software DeweFRF provides you with help on every aspect of working with the program explain basic steps to do online or offline and single input P e single output SISO modal analysis how to work with First time users Tuto ria S projects and how to import export measurement setups geometry and FRF modal data Detailed beside four basic procedure Channel and FRF setup Measure and Analyse includes also Offline calculation fun ctio de U ser g u id e DeweFRrF software interface and Data management how description to load save measurement setups geometry and FRF modal data explain System requirements for work whit DEWE software appropriate hardware and general DeweFRF Refe rence g u To e System setting this guide also contains
146. t management tutorial Project file 4 1 Project file In Project Channel setup data FRF Setup data and Geometry data are stored New project epg impo Bout Sms e New project LUN naw geometry Open project p Save project a Save project as We can open New Project Channel setup by selecting File menu New project Open project AEREA te Hew project New geometry Ce MT save pruect WH Save project as Ajmer 2 Palica _Proj_Test We can directly import existing Project Channel setup data by selecting File menu Open project in standard Open window we choose name of existing project or by click on File menu name of recent project by this option project opens automatically Basic Channel setup screen is displayed for defining data and setting of analog channels which will be used during measurement excitation and sensors in Analog and Analog out tab Define new Project data For detailed information see User Guide Import Export Project file gt Save Project Modify existing Project data In Project file Channel setup data FRF Setup data and Geometry data are stored After define modify Project data we can save this data in project Save project BS dew proect Mas geometry G Goan projet E Save project We can save existing or new Project Channel setup data by selecting
147. te the geometry on geometry window After geometry rotate Go pa DeweFRF v6 5 User Guide v1 2 0 page 95 2007 DEWESoft Geometry window toolbar FRF Setup Geometry window a Zoom When this button is pressed we can left click and drag the mouse anywhere inside the geometry widow from outside to center to extend zoom in the geometry or drag the mouse from inside outward to contract zoom out the geometry Even if rotate is the default option we can zoom with Control click on geometry a Point Maker With this button we can set up Point Maker for define new or modify existentgeometry For detailed information see FRF setup gt Point Maker All geometry display tools are accessible with pressing on appropriate button icon When you choose these tools it is very important what part you wish to see clearly Fi Arrow When this button is pressed we can observe in the Geometry window arrows and directions of excitation or response in constructions points This is an on off switch button Arrow switch is off PA 1 e Nodes number When this button is pressed we can observe all numbers of nodes assigned to construction This is on off switch button Nodes number switch is off ra ia al DeweFRF v6 5 User Guide v1 2 0 page 96 2007 DEWESOft Geometry window toolbar FRF Setup Geometry window P Trace line When this button is pressed we can observe all trace
148. the input of the start end and all the nodes between in the TraceLines table The column TraceLines is selected using the left click In this column the Nodes Tracelines Objects name for the trace line is entered TraceLines Trace line 2 Taca ine 3 During the input for the name of the trace line an empty cell for the entry of the next trace line is displayed in the left column We can select it by Trace ine 2 left clicking The name for the trace line is also displayed in the header of the right column which also contains the first empty cell for the first node input The cell for the node input is selected using the left click During the entry of the node the cell for the next node is created below Value of node is only a number The next cell is selected either by left clicking or using the Tab key For detailed description action with keyboard keys see gt Navigation keys First the TraceLines has to be selected by clicking from the Point Maker menu In the Point Maker the following basic procedures for trace lines exist lo xl ae Tn 0 DES EME Traceles Trace line 2 Trace ine 3 T ine 2 e New trace line PERS 4 e Edit trace line e Delete trace line Delete all traceline New trace line When we choose File menu New Geometry Or when in geometry there is no defined trace line then selecting TraceLines on toolbar creates the following table ines Object
149. the on screen electronic version of the help much more useful Getting started Start by studying the Basis of work with DeweFRF and DeweFRF software interface See DeweFRF tutorials sections for some basic tutorials to get you started with using DeweFRF eg Four step tutorial Calculation tutorial SISO Single 1 0 modal analysis tutorial and Project management tutorial Working procedures To learn how to do something consult the working procedures section DeweFRF User Guide which beside four basic procedure include also Offline calculation and Data management Learn about For additional information about modal analysis see the DeweFRF Reference Guide and Analysis background Using the help while you re working As far as possible the help separates instructions and background information This makes it much easier to refer to the how to instructions All sections have extensive links to the other relevant sections so it doesn t really matter where you start Getting a printed user manual Please don t try to print the HTML Help version of the help from the Microsoft help viewer as it would look terrible You can get the formatted PDF version of the entire documentation designed for printing from the installation CD As mentioned above however you will probably find that the on screen version of the help is much more useful because of the hyperlinks and cross references DeweFRF v6 5 Welcome to DeweFRF v1 2
150. then drag on desired region therefore expanding this region on whole scale of x coordinates With right mouse click we return the default size of x coordinates 6 3 Geometry window On Geometry window we can see geometry nodes points of mechanical structure to which a channel for each excitation and response is defined as well as trace lines global coordinate system and when entering arrow with indexes directions and signs will be shown It is very helpful to load the geometry to get a feeling where to locate excitation and response About Import Export Geometry data see User Guide Data management gt Geometry If the geometry has been created or loaded the deflection shapes can be observed with animating the points on the structure or showing the maximum deflection shapes see Analysis tools chapter for explanation click on field of interest NS L GEOMETRY window TE tines toolbar buttons for x toolbar geometry setting in ANALYSE procedure coordinate system DeweFRF v6 5 User Guide v1 2 0 page 124 2007 DEWESoft Analyse Geometry window Geometry window TOOLBAR is divided in three parts 1 MANIPULATE with geometry al u are the same as in FRF setup see gt Manipulate geometry a Ar a 2 Geometry DISPLAY SETTING l are the same as in FRF setup see Display setting 3 Particularly for Analyse procedure are on Geometry window toolbar two button e SCALE
151. tic functions are activated as a standard Please read more about DEWE softwares mathematics in DEWESoft Manual Online mathematics Hardware setup Mathematic functions are activated by checking appropriate checkbox DeweFRF v6 5 Reference Guide v1 2 0 page 157 2007 DEWESoft Licensing Hardware setup A new licensing tab offers the possibility for easy license handling of software and options You have to enter your Username and User location first then click into the License key s field and enter your license key s DeweFRF System setting Hardware setup Use name User location T Evaluation icense DEWE TRON Avista Grar Grambach pra peor perrea SD boards 12345676 1234567 Regsirsbon stalus PROF est If the license key is correct the red cross in Status will be replaced by a green check mark and the registration status displays the version LT SE Standard Edition PROF Professional Edition DSA Dynamic Signal Analyzer Save hardware key list For systems with several A D boards or other sources it is possible to store a hardware key s list into file dwkey To do that simply right click in the licensing table and select Save hardware key s to file This file is usefull for DEWETRON to make the installation easier 297 0313 LOAD ina out from file No hardware key Load license code s from file As mentioned above systems may contain sever
152. tion signal however the use of it is doubtful since the response to a double hit can t be rejected DeweFRF v6 5 User Guide v1 2 0 page 91 2007 DEWESoft Impulse hammer excitation FRF Setup FRF property panel setting Response decay The window for response is automatically an exponent down with a defined decay Decay is the attenuation factor at the final sample of the signal So if we define 5 response decay the final window value will be 0 05 The response decay increases the damping of the structure The response decay can be used if the structure damping is low to reduce amplitudes at the end of calculation window Pretrigger Pretrigger defines the number of values which are taken before the actual trigger occurs Trigger level Is the level of the first excitation channel where the FRFs are acquired It always triggers on rh H F the positive edge of this level The trigger level and pretrigger value can also be chosen visually in excitation scope The trigger level is visually represented by the yellow horizontal line The cursor changes to arrow when the mouse is moved over this line Then we can move the line with left mouse click and drag The pretrigger is shown as the vertical yellow line and the value can be defined by clicking and dragging this line as well 4 2 Transfer function selector The transfer function selector shows the matrix of selected excitatio
153. to the deleted node are also deleted Navigation keys Navigation keys are in TraceLine column to use in same manner as in another text processors In right column to be worth lt in number one digit left _innumber one digit right Tab tothe next cell in the column Shift Tab tothe previous cell in the column upone cell in the same column up one node Y downone cell in the same column down one node Home in number to leftmost digit End in number to rightmost digit PgUp first node in the column PgDn lastnode in the column Enter select the entire number in the cell Backspace deleting the left digit in number while editing the coordinate or entire number when this is selected Delete deleting the right digit in number while editing the coordinate or entire number when this is selected DeweFRF v6 5 User Guide v1 2 0 page 106 2007 DEWESott Objects FRF Setup Point Maker Point Maker can create the following objects faster e Grid e Circle First we select by clicking Objects in the menu Grid In the table of parameters the values Number of Nodes Delta distance between nodes Offset distance of first node from 0 value of coordinate and Rotation Angle turn around for any of the particular coordinates X Y in Z are entered The choice Create with TraceLines is checked if the trace line between the nodes is desired Value of parameters is only a number In Delta Offset and Rotation Angle a
154. tored data for reload stored data in Channel setup procedure of directly measurement e Channel setup From stored data define range of stored and reloaded data Show and Start show Time for recalculation e FRF setup forstored Time data define DeweFRF software same as for directly measurement except Frequency span e Calculate stored Time data recalculating in Channel setup defined range stored and reloaded data e Analyse calculated Time data analyzing recalculated data same as for directly measurement On Ch setup procedures window of directly measurement for explanation click on field of interest Devret HF 5 x Live measurement Meur ee as Ele Import Export System DIRECTLY while P ie ESA Sra acquiring data rate allowable HR FE jee a Store data during expensive calculation then can reload and calculate stored data Define and set all the channels which will be used during measurement iiti 10 200k oa we can choose e Store time data for store segment of measure data e From stored data for reload stored data DeweFRF v6 5 User Guide v1 2 0 page 133 2007 DEWESoft Offline calculation Channel setup After selecting From stored data and entering required file in File name we reload stored data and get Ch setup From stored data window with Time overview bar with Time selector of stored data on upper part of window and Display of stored data with complete stored signals in th
155. ts of the forces and responses which the structure allows First of all we have to select one channel either excitation or response If the channel doesn t have the user defined range then the entry field shows Not set If we want to enter the range we have to type in the value and press Set button If we want to set the values for all the channels the Set to all checkbox have to be set prior to clicking on the Set button DeweFRF v6 5 User Guide v1 2 0 page 89 2007 DEWESoft Continuous shaker excitation FRF Setup FRF property panel setting Several settings are set in FRF property panel gt FRF MENU for Continuous shaker excitation type e Calculation type e Window type e Overlap Calculation type FRF MENU Calculation type If the excitation is shaker or electrical signal of any kind of noise or sine sweep Free run Triggene the Free run method is used to calculate the FRF Window type The window type defines the FFT window which will be the same for all excitation Rectangular and response Rectangular Hanning os The window adds the damping of frequency modes but they are necessary to Triangle avoid leakage on sweeps or noise Blackman Esponent down The rectangular window is therefore not recommended but Hanning or Blackman would be a good choice Overlap When the window is used we have to use overlap otherwise some of the data will be ignor
156. u J Pi Bif poe eB pal pa E F a 4 p 3 E b FAP arpltoda mea LS FAP r quiresy dona min T DeweFRF v6 5 User Guide v1 2 0 page 120 2007 DEWESoft Analyse Analysis screen consists of two major parts e The list of measured FRFs Here you see all the measurement data on the left e By selecting the items in the list on the right top will be shown the display of FRF result graph in FRF graph and geometry in Geometry window If more channels are to be measured go back to the FRF setup change the point indexes do another measurement and confirm will add it to all measurement result The entire setup not the data files can be stored with File gt Save project as a project file to reuse it later 6 1 List of measured FRFs Graph with measured FRFs displays only FRFs which are selected in list of Measured response functions Measured response functions Displayed FRFs The list of measured FRFs is the selector for the display shown function are designated with white ink color in Exc Resp column of the list Individual FRF can be selected by e dragging with mouse from the FRF in Exc Resp list to graph e selecting items with left click More FRFs can be shown by selecting items with Shift Left click or dragging on the list with Left click Delete FRF from list By this action FRF is removed from graph and from list of Measured response functions Individual FRF ca
157. ulation or control purposes The right area bellow Waveform finally contains the sliders to change Amplitude Offset and Phase For input precise entries each this value is next to the slider also numeric field simply click in the field and enter the desired value directly with your keyboard For Arbitrary and Noise type of waveform are beside sliders and numeric fields also additional signal setting The lower left area shows a nice One period preview of the selected signal DeweFRF v6 5 User Guide v1 2 0 page 81 2007 DEWESoft Channel setup FRF Channel Setup Analog out Signal setting Use this channel output as The channels can be used as signal output for the selected waveform is default or trigger output Each channel can be set to trigger output instead of signal output Signal settings Use this channel az signal output Often it is intended to trigger the acquisition on measurement side when certain criteria is met When the sweep is active the trigger value goes up It is up at step sweep at fixed frequency and during the bursts Channel setup for channel 0 E 3 xx General settings y Signal setings Channel name Linits Color Min value PATATA Max value pi a re period preview Trigger Waveform The channels can be used as signal output for the selected waveform Waveform drop down selection has a direct influe
158. ve Geometry windows we can see a screen shot of bending animation of shapes in eft most position on next screen shot however in right most position DeweFRF v6 5 User Guide v1 2 0 page 127 2007 DEWESoft Animate Analyse Analysis tools MSIE mm fA BE If by animation a static picture of maximum deflection shape is requested Max shape option can be chosen It is like freezing the animation at the time where the structure would be maximally bended DeweFRF v6 5 User Guide v1 2 0 page 128 2007 DEWESott Max shape Analyse Analysis tools If the geometry has been created or loaded the deflection shapes can be observed with showing the maximum deflection of shapes or if by animation a static picture of maximum deflection shape is requested Max shape option can be chosen lt is like freezing the animation at the time where the structure would be maximally bended PERS Mas shape With selecting this button we can see maximum shapes deformation Fe A After selecting Max shape button instead of this we get Reset button to return of Animate Reset geometry in initial state without deflection however Animate button is disabled Fle Import Export System O EAO 3 Loe LA ds A OO A cn az eb Ch setup FAFsehp Cakulate nas Delete Dektesl Grinds Reset Cucie Bt Tockpbosd UFF export info DeweFRF v6 5 User Guide v1 2 0 page 129 2007 DEWESoft Circle fit
159. w 3 by select of From stored data choice FIT Teese File name fet tas For detailed information see Offline calculation Decision what to do depends on the user if the archive time data is needed and on the system performance The system benchmarks might differentiate from system to system but with recent computers 3 GHz P4 it is possible to measure online 256 channels at few kHz bandwidth DeweFRF v6 5 User Guide v1 2 0 page 44 2007 DEWESoft Data management 2 Data management In Dewesoft FRF there are many ways to Import Open or Export Save setup geometry and measured data type of file type of data action Channel Setup Setting of all analog channels for excitation and responses FRF Setup Project Assigned points of structure to channels New Open and setup parameters for calculation dfs Dewesoft FRF project data file Save Save as Geometry Defined geometry and nodes of mechanical structure Project doesn t include measured data Measurement Setup Channel Setup dss Dewesoft setup data file or Setting of all analog channels for Dewesoft text setup file excitation and responses Geometry Geometry New Import l l Defined geometry and nodes of unv Universal file format data file RE pe Export Modal FRF Data ne FRAPPE unv Universal file format data file Export Time data Load time data measured data i dsd Dewesoft data file Store t
160. w file name and store data under this name DeweFRF v6 5 Tutorials v1 2 0 page 20 2007 DEWESoft Calculation tutorial Channel setup After pressing Store time data button on Ch setup and Yes on Warning screen we now see this screen In place of Store time data the Stop button appears By pressing on DeweFRF E E kale ES Fie Import Export System Ch set FAF setup Messur Analyse de Pram mencuit File name os Freg span 2000 Pee ia From sored cate Fite path C Deweton Progam DEWE Soit App DeweF RFiDatal button we get display screen of stored data in certain time For detailed information see User Guide Data management Time data Reload Dewesoft time data To reloa d data choose From stored data and define the File name for loading The Measure tool button is changed to Calculate to show that data will be taken from stored file If the channel setup of Dewesoft includes the recorder the data region o f interest can also be chosen by zooming in the recorder To follow the steps with demo data please open EimerNoise dsd You will get the screenshot as shown below Fee Import Expert pysten Me rh LH Hi i show Start show time Ch setup FAF setup Caouse Ang white bordered rectangular SN De ASE De RE TR q indicate range of stored data stored data From manure File name Time overview bar f From Hoei dis File pase Epia SI MPA Y fa iB loj x
161. we calibrate the system so that the channel real volts equals 0 N and mV electrical units equals For other channel and Scaling by two points by function Second point First point Calibrate from average from RHS Calibrate from average from RHS Back to Channel setup Scaling Channel name in General part of channel setup screen of this example Channel name in General part of channel setup screen N engineering units Force real volts equals 0 y mV electrical units equals 1 g engineering units Acceleration A ln na r LLE TA Tr 10000 m 4769 0 mY 121 2 mY 4517 8 mY 10000 m Back to Analog channel list DeweFRF v6 5 2007 DEWESOft User Guide v1 2 0 page 67 Channel Setup FRF Channel Setup Analog Another way to perform such a simple linear function would be to simply multiply the input by a factor You can easily do this by clicking the by function button which will change the two point calibration portion of the dialog to look like this Set zero In our example we calibrate the system so that for channel A 0 Channel name in General part of channel setup screen this factor is 0 02 Above shows your basic y mx b algebraic formula for a general linear function which makes it easy to input strain gage k factors and offsets n factor as well as to perform simple offset calls like the conversion from Celsius to Fa
162. xt exc F10 Mext resp F11 Channel Excitation Response i Point index Ey Channel Excitation Response Pointindex Resp ET erg There are two more controls which appear only if just one excitation and response channels are defined first option is Next exc F10 which confirms the measurement and moves the point index so that excitation point is incremented by one This allows us to immediately measure next point on the structure Next resp F11 does the same but it will move to the next response point Ae Import Export System NT IE Ait Ex El Aa e Ch seup FPF teip Meriva Snake Aerea FE epee leet Ff Slag Contra Fo Mec ce PT M l re ge 111 ot sg a cr ro ae e Barrens chess rT ed po x 500 1000 150 2000 01 In our case we decided to move the excitation point We press Next resp F11 The table on the right side will show 2z as the next measurement point indicating that we should next hit on point 2 We do all the measurement in the same fashion up to point 8 to get all the FRFs For the last measurement we press Confirm to go to Analyse mode DeweFRF v6 5 Tutorials v1 2 0 page 34 2007 DEWESoft SISO Single 1 0 modal analysis tutorial Analyse The analysis is the same as described in basic tutorial 4 A re a a mn C oz p hirbetas Debate all Retnescure anale Mas thapa Cice M To cipboard UFF sxporl Indo T
163. y import load existing previously saved Modal FRF Data measured data from unv data file into Analyse screen by selecting Import menu Modal FRF Data My Recent 1 Documents E E oe ral Ej Cube un Desktop Eimer unv 4 EimerFRFs uny oS EimerGeo unw My Documents Hammi_12Feb unv 4 Hamm2_12Feb urm E Hamm3_12Feb urmr ON A Palca Help_osnuny 2 Palcab_test urr a Mois mre a Export Modal FRF Data to save new or modified measured data to unv data file we have two feasibility Ch setup El Measurement setup For export save Modal FRF Data measured data UFF export on Analyse toolbar gt FRF data select here we have optiions for selecting another sort of data to save eg Coherence Excitation data All data Export menu gt Modal FRF Data DeweFRF v6 5 User Guide v1 2 0 page 52 2007 DEWESoft Data management Modal FRF data In both case Save FRF data As window is displayed for save new or modified Modal FRF Data measured data to nv Universal file format data file brad E 2 Hamm3_12Feb uny Ae A Palicad_Help_osn unv 2 Palica6_test uny Fle name Save as ype Unversal file format Cancel WARNING because Geometry and Modal FRF Data are stored in same unv Universal format file it is strongly recommended to use separate filename for new or modified Geometry DeweFRF v6 5 User Guide v1 2 0 pa
164. yed see graph above The coherence is used when multiple data is acquired for single FRF e The other two selections are linear or logarithmic amplitude and frequency plots For Excitation Response scope we can select auto scale y coordinate FA Auto Scala yw axis DeweFRF v6 5 User Guide v1 2 0 page 116 2007 DEWESoft Measure Graph Display Excitation current averaged FFT For Excitation current averaged FFT we can select auto scale y coordinate logarithmic x axis Coordinates Scaling Each graph has x and y coordinates scaling possibilities 1 Edit minimum or maximum value for x and y coordinate This works for all graphs except with only one exception upper one of Frequency response function display El ara ida ER E A A Ex Hi qi If we move with the mouse over the minimum or mt mn ski j ni Hy sill AIAN wi Ti if a maximum value for x and y we can enter custom value in by clicking with left mouse button and entering the value IN oe mm me A pal jh Hed ui Hi pal ty is s h y LR E su T TF 300 T i nl j i PEF SEN 1 Perk UE aaa o e e e e CE OC CS COR o cn i L 1 i dal sr ii ma fon ong iL I ji Ll 1E E Amplitud DeweFRF v6 5 User Guide v1 2 0 page 117 2007 DEWESoft Measure Graph Display 2 Coordinates scale of FRF graph Scale x axis can be done by mouse click on For FRF graph we a

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