Running ABAQUS 6.9 (PDF Format)
Contents
1. Procedure Type Preselected element Preselected nodal and Preselected energy variable field surface variables variable written field history STATIC S E PE PEEQ U RE CF yes PEMAG CSTRESS CDISP FREQUENCY U no This represents the information written the output database odb file As can be seen there is no need to list the pre selected variables Additional output parameters can be added if necessary For example CF If you want to plot the force vs displacement at a given node xRestart write frequency 1 k x FIELD OUTPUT F Output 1 k xOutput field variable PRESELECT k HISTORY OUTPUT H Output 1 k xOutput history variable PRESELECT By default no results are written to the results file res This keeps the dat file to be compact This is favouring visualisation of the results in terms of graphical plots contours deformed shape graphs etc and less of printing of several tables of stresses strains and displacements which are hard to fathom at the best of time However there are times when debugging or carrying spot check of calculation for a benchmark problem when printed output is needed For this case the following statements allows one to print out the results for checking purposes NODE PRINT FREQ 1 NSET _G4 U RF This writes out the nodal displacements U and the reaction forces RF to the dat printed output file The setting of the parameter NSET res2. ABAQUS User Subroutine Reference Manual ABAQUS Glossary Manual Oo N DT oO EF Q N ABAQUS Keywords Reference Manual Volumes I and II m Verification Manual ABAQUS Scripting User s Manual ABAQUS Scripting Reference Manual ABAQUS Release Notes a e WwW N ABAQUS Installation and Licensing Guide 1 2 Programs 1 INTRODUCTION 1 2 Programs ABAQUS Standard and ABAQUS Explicit are both available in the CUED teaching system comput ers ABAQUS CAE is the pre processor and ABAQUS Viewer in the post processor PATRAN is an established pre and post processor for ABAQUS ABAQUS Design is suitable for parametric study and optimisation 1 3 Where to Start Figure 1 shows the inter relationship between the ABAQUS Analysis module and the pre and post processor modules CAE and Viewer e If you want to make a start using ABAQUS with the minimum amount of reading to get famil iarised with running simple problems then start with the ABAQUS CAE User s manual Ap pendix B tutorial of A loaded cantilever beam This takes one through pre processing analysis and post processing from within the graphical interface ABAQUS CAE Appendix D covers output post processing aspects In Chapter 4 there is a further tutorial dealing with advanced techniques If you want to familiarise yourself with the structure of the ABAQUS input data then work through the example given in this handout and try running the example s
3. ODD UWN This is followed by the reaction forces at nodes which are restrained NODE FOOT RF1 RF2 NOTE T 102 6 42 06 4 5 78 19 78 7 97 41 38 16 For the second frequency step the eigenvalues and frequencies are listed for each mode that had converged EIGENVALUE OU TP UT MODE NO EIGENVALUE FREQUENCY GENERALIZED MASS COMPOSITE MODAL RAD TIME CYCLES TIME DAMP ING 1 1 10800E 07 3328 7 529 11 156 71 00000E 00 2 6 44741E 07 8029 6 TAII 165 92 00000E 00 3 6 46343E 07 8039 5 1279 5 147 12 00000E 00 4 8 48167E 07 9209 6 1465 8 137 42 00000E 00 5 1 44871E 08 12036 1915 6 200 78 00000E 00 This is followed by the stresses strains and nodal displacements for each eigen mode 6 Running ABAQUS Viewer ABAQUS Viewer is an interactive post processor for ABAQUS It reads the output database file odb generated by a ABAQUS run and allows the user to plot the results as views of the deformed mesh contour plots variable against variable plots XY plots The plots generated using ABAQUS Viewer may be saved to a file in a number of formats or directly printed 6 1 General Type abaqus viewer to run ABAQUS Viewer Type abaqus viewer database plate1 to run ABAQUS Viewer with platel odb To quit from ABAQUS Viewer from the main menu bar select File Quit 6 2 Mesh Plots From the main menu bar select Plot Undeformed Shape or use the the tool in the toolbox shown below To display the mesh with node and eleme
4. Then the data lines are omitted The following statement completes the first step End Step Since we are interested in the eigenmodes of this example then a second step as shown can be included Step name eigenmodes perturbation eigenmodes Frequency eigensolver Lanczos 5r rrr END STEP The FREQUENCY tells the program that this step is a frequency analysis this should not be con fused with the FREQUENCY parameter used in the output options where it refers to increment num bers and the number 5 which follows means that the user is only interested in the first 5 eigenmodes The complete input data is listed below Heading deformation eigen xx Job name cantiever Model name Model 1 Units Length m Force N Stress N m2 Time Sec Preprint echo YES model YES history YES kk xx PARTS xk Part name plate End Part kk xx ASSEMBLY kk Assembly name Assembly kk Instance name plate 1 part plate Node L Ogy 0 25 034 0 3 A 0 17 2 2 ABAQUS Input 2 DATA PREPARATION 4 Bug 0 5 Dy 01 5 0 5 6 Ley 0 5 ue OM 1 8 0 5 Di 9 La Is Element type CPS4I Tal py 2 2p S767 S Bip sly ADI pA pA AD E Di 8 Region Section 1 Picked Elset elset _11 internal generate 1 4 1 Section Section 1 Solid Section elset _11 material steel 0 05 End Instance Nset nset _G4 internal instance plate 1 generate Vi Wy 8 Elset elset _G4 inter
5. Click on OK If a dialogue box called Select plot Mode appears then choose the toggle option o As is and click on the OK button This should draw the displacement vectors in Red 6 3 Displacement Plots and Getting Hard Copies A hardcopy of any generated plot can be obtained by directly printing to a Postscript printer Alterna tively the plot can be saved in a Postscript PS Encapsulated postscript EPS Tag Image File Format TIFF or Portable Network Graphics PNG file To get a hard copy of the plot from the main menu bar select e File Print In the print command line type lp oraw d lt printer name gt Example lp oraw dljmr1 29 6 4 Contour Plots 6 RUNNING ABAQUS VIEWER 6 4 Contour Plots To plot the Contours of von Mises stress e From the main menu bar select Result Field Output e In the Field Output dialog box Select S from the list Output Variable and then click on Mises in the Invariant table Alternately click on the Plot Contours icon Click on Apply Sometimes it might be necessary to produce a black and white output where instead of banded plot only lines with labels or different linetypes are required In order to obtain such a plot click on the Contour Options which can be seen just below the bottom right hand corner of the Viewport In the Contour Plot Options dialog box click on the Basic tab In the region marked Colour type toggle on the Line option Then click on the Color amp Sty
6. Constraints 30 Constraints Part 9 Interactions 31 Defining Contact Interaction 32 Contact Property Models 33 Contact Formulation and Numerical Methods 34 Contact Difficulties and Diagnostics 35 Contact Elements in ABAQUS Standard 36 Defining Cavity Radiation 36
7. This results in the load being applied in small increments fractions For the following setting time step of 0 01 for first increment the first 1 of the total load is applied during the first increment in the step Depending on the rate of convergence the load fraction is increased in subsequent increments until the total loading has been applied In the absence of the NLGEOM parameter the problem will be treated as linear elastic and the geometry is not updated ie the nodal coordinates are not updated by the displacements that take place during the analysis and in the second step the eigenmodes will be calculated based on the original geometry hence the loading applied will not have any effect on the mode or the frequency STEP AMPLITUDE RAMP NLGEOM INC 100 xSTATIC 0017 1 0 S S E des 0 The data consists of initial time increment 0 01 total time step 1 0 minimum 1 E 5 and maxi mum 1 0 time increment allowed RESTART WRITE This creates the restart file res which is also used for re starting the analysis This record can be included anywhere but here it is included before the first STEP record For a large analysis with many elements and steps the restart file can be very large several MBytes To reduce the size of the restart file add the frequency option RESTART WRITE FREQUENCY N Where N can be a suitable number appropriate for the no of increments used in that step For example if you are using 100 inc
8. better to use the incompatible mode element In general the higher the order of the element the more accurate will be the results for the same level of descretisation CPS4T is a 4 noded bilinear incompatible modes Plane Stress element ELEMENT TYPE CPS4I xx Element Node 1 Node 2 Node 3 Node 4 Ly t 2 5 4 2 2 35 6 5 First number in each line is the element number and this is followed by the node numbers listed in the anti clockwise sequence Gaps are permitted in the element numbering 12 2 2 ABAQUS Input 2 DATA PREPARATION Elset elset _I1 internal generate dy Aye OL This creates an element set labelled _I1 and the parameter generate causes the elements 1 to 4 to be created with increments in element number being 1 In the following input the elements in the element set _I1 are specified to have SOLID SECTION with a thickness of 50 mms in the direction normal to the paper and they are also assigned the STEEL material properties which is defined below Plane stress and plane strain analysis deal with problems where the structure is subjected to in plane loading In the current example if the loading is transverse ie normal to the plane of the plate then this ceases to be a plane stress problem It becomes a three dimensional problem Then you need to use shell example S4R5 S8R5 elements Solid Section elset _I1 material steel k xx thickness 0 05 The next statement completes the instance definition I
9. click on OK The path has now been defined Next step is to select the variable to plot There are 2 ways of selecting the variable for the plot The first way is same as selecting a variable to draw contours 30 6 6 X Y Plots 6 RUNNING ABAQUS VIEWER From the main menu bar select Result Field Ouput In the Field Ouput dialog box Select S from the list Output Variable and then click on S11 in the Invariant table This selects the variable ozz The next step is to generate the path plot The second method of selecting the variable is included in this From the main menu bar select Tools XY Data Create In the Create XY data dialog box toggle on Path and then click on Continue In the XY Data from Path dialog box make sure Path is set to vertical the previously created path In the region marked Y Values Click on Field Output and select S as the output variable and S11 as the Component This is where a different variable can be selected subsequently Click on OK Then in the original dialog box click on Save As and give it a name example s11 on vertical Then click on Plot This should display the Path plot in the main viewport If the Select Plot Mode dialogue box appears then toggle on As is and then click on OK Once a path has been defined it is possible to plot the variation of a different variable example Mises stress along this path 6 6 X Y Plots In the current analysis the loading w
10. fil res solution files files used in solving the FE equations are created in the scratch directory In the teaching system tmp is the scratch directory In general tmp has about 9 GBytes available tmp is a temporary workspace shared by many different programs while these es execute and care is needed when using this region in running ABAQUS jobs DO NOT A use this as an extension to your home directory or to store large files over a long period which is likely to seriously inconvenience other users If in doubt ask the computer operators Before starting a large analysis you need to find out the system requirements mem Warning ory and size of solution files In order to obtain this information run the job with the datacheck option abaqus job cantilever datacheck In the dat file look for the heading File sizes under Problem Size An estimate of the size of the total solution files will be listed If these exceed the free unused space available in tmp then the analysis could not be run To continue a job run using the datacheck option type abaqus job cantilever continue If you are using a research system and if you want to override the default setting of tmp then in the abaqus_v 6 env file include the following statement and set the scratch parameter to a directory which has sufficient disk space scratch aba_tmp Here the directory name aba tmp is used as an example Using this in the teaching system will cause
11. in the page to which you are jumping to it might take a while for it to display it By clicking on the gt one can open up the subheadings Subheadings and subsections can be closed by clicking on the appropriate t sign To quit from the on line documentation choose File Quit from the first window Volume 1 Part 1 Introduction Spatial Modeling and Execution 1 Introduction 2 Spatial Modeling 3 Execution Procedures Part 2 Output 4 Output 5 File Output Format Volume 2 Part 3 Analysis Procedures Solution and Control 6 Analysis Procedures 7 Analysis Solution and Control Part 4 Analysis Techniques 8 Analysis Techniques Introduction 9 Analysis Continuation Techniques 10 Modelling Absractions 11 Special Purpose Techniques 12 Adaptivity Techniques 13 Eulerian Analysis 14 Extending ABAQUS Analysis Functionality 15 Design Sensitivity Analysis 16 Parametric Studies Volume 3 35 9 1 On line Documentation 9 FAQ AND OTHER INFO Part 5 Materials 17 Materials Introduction 18 Elastic Mechanical Properties 19 Inelastic Mechanical Properties 20 Progressive Damage and Failure 21 Hydrodynamics properties 22 Other Material Properties Volume 4 Part 6 Elements 23 Elements Introduction 24 Continuum Elements 25 Structural Elements 26 Inertial Rigid and Capacitance Elements 27 Connector Elements 28 Special Purpose Elements Volume 5 Part 7 Prescribed Conditions 29 Prescribed Conditions Part 8
12. of these parameters can be found by typing abaqus info environment In case of problems with the Graphics on a Windows XP System include the following line in the abaqus env file abaqus_no_hardware_acceleration ON 3 4 Checking for Errors For small jobs or jobs which fail quickly use the interactive option on the command line This will pinpoint which file to look at in case of errors If you have not used that option then look at the log file This is the quickest way of finding out whether any errors have been detected in the ABAQUS run The log file will contain the same information which is written to the screen when the interactive parameter is used The absence of the odb file when you are expecting it to be created is also an indication that there are errors in the ABAQUS run If the msg file is missing then the errors must have been detected at the datacheck stage ie while running pre x The dat file always has a summary at the end and will list a count of all the errors encountered If the dat file had terminated abruptly without this summary and if there are no errors listed in the dat file then it could be that your disk quota has been exceeded while creating the various ABAQUS run time files Check your quota by typing quota v Delete all the old dat fil and res files and any other unwanted files Contact the computer operators if your disk quota needs to be increased If you are not going to use the restart o
13. the ABAQUS program to fail because such a directory does not exist If you are running very large analyses then the disk space in the scratch directory may not be sufficient If this happens ABAQUS may issue messages similar to the following 1 Error Sequential I O error on unit 21 Out of disk space or disk quota 2 scratch directory write failed file system is full direct access I O Error on unit 2 Out of disk space or disk quota exceeded Type df tmp to find out how much unused disk space is available If this is only a few Megabytes then tmp on that particular cluster cannot be used Report this to the Computer Operators giving the details of the cluster tmp is local to each cluster Try slogging into another cluster where there is plenty of unused disk space in tmp 3 3 ABAQUS Environment File abaqus_v6 env The default setting of memory etc can be changed by setting alternative value in the abaqus_v6 env file The settings for a particular job which has been submitted can be found in the com file For example to increase the memory from the default 2800 MB to 4000 MB include the following line in the abaqus_v6 env file If this file does not exist then create this file in the current directory using a text editor memory 4000 MB 24 3 4 Checking for Errors 3 RUNNING ABAQUS See section 3 4 1 of the User s manual Volume I for a complete list of the ABAQUS environment parameters The current setting
14. the element type has been identified in the same section a list of active dof type of loading that can be applied to the element type and the output parameters available for these elements can be found Look through the Element Index in volume II for the element types Look through the Keywords Manual to check the various keywords Follow the references to the Analysis User s manual Refer to the sections which are relevant to your analysis 2 DATA PREPARATION Chapter 29 volume II has information on loading and boundary conditions Chapter 30 has information on MPC Multi Point Constraints Information on contact problem can be found in chapters 31 to 35 Section 4 1 1 Volume I deals with the output from ABAQUS Search through the contents of the Example Problems Manual to find the examples in the field of your interest Look through the contents of the Verification and Benchmarks manuals to find the examples in the field of your interest Another useful source is the course notes of the various courses run by SIMULIA Ltd e Run an example problem and familiarise yourself with the various files and in the use of the various program modules ABAQUS ABAQUS CAE ABAQUS Viewer Output Variable index can be found in OL1 nad OI 2 for Standard and Explicit respectively EI 1 and EI 2 has the Element index for Standard and Explicit versions respectively Start with a simplified situation of your analysis with very few elements s
15. the manual the second option of representing the job id with an asterisk will be adopted Model data defines the finite element model the elements nodes element properties ma terial definition any data that specifies the model itself History data defines what happens to the model the sequence of events or loadings for which the model s response is sought In ABAQUS the user divides the history into a sequence of steps Each step is a period of response of a particular type a static loading a dynamic response a soils consolidation transient etc The definition of a step includes the procedure type static stress analysis transient heat transfer analysis 2 2 ABAQUS Input 2 DATA PREPARATION etc control parameters for time integration or the nonlinear solution procedures the loading and output requests The procedure option defines the type of analysis that will be carried out during a step A pro cedure option is required for each step and must follow immediately after the STEP option Any mixture of procedures may be used from step to step but only one procedure is allowed in any single step STATIC is one of the procedure options used for the example here It means it is a static analysis Here follows the list of procedures available in ABAQUS see section 6 1 of the Analysis User s manual for a procedures overview BUCKLE COUPLED TEMPERATURE DISPLACEMENT steady state and transient COUPLED THERMAL ELECT
16. yDisp 9 in the name box in the Save XYData As form Then click on OK Notice the note XYData are only saved for the current ABAQUS session Click on Plot in the original dialog box Repeat these steps for the Output Variable with the description Point loads CF2 at Node 9 Save this as yForce 9 6 7 Creating a Force Displacement Plot Combining the plots created in the above section the Force Displacement plot can be created as follows From the main menu bar e select Tools XY Data Manager In the XY Data Manager dialog box click on Create In the Create XY Data dialog box toggle on Operate on XY data and then click on Continue The Operate on XY Data dialog box appears This contains the following lines The XY data field on the left has a box for entering an expression Below that a list of existing X Y data objects this should have the 2 plots created in the above section The operators s field on the right contains a list of all the possible operations you can perform on the data object From the operators field click on combine x x combine appears in the expression box Double click on the XYData yDisp 9 and this will appear within the brackets 32 6 8 Writing Out Results 7 POST PROCESSING USING THIRD PARTY PROGRAMS e Type a comma and then double click on the XYData yForce 9 The expression box should look like combine yDisp 9 yForce 9 e Then click on Save As bu
17. 7 2 x 2 integration scheme for CPS4I Element END OF USER INPUT PROCESSING This indicates the end of the pre stage of the analysis Next comes the results from the analysis proper the results output for information requested using the NODE PRINT or EL PRINT keywords in the inp file For the example problem under consideration this consists of stresses at element integration points Fig 7 The stresses at the 4 integration points at each element are printed S11 522 and S12 represent O xx Cyy And Try respectively for this element type CPS4I ELEMENT PT FOOT 11 S22 S12 NOTE 1 T 6615 1083 2450 1 2 6615 285 2 2450 1 3 2554 1083 2450 1 4 2554 285 2 2450 This is followed by the strains r2 yy and xy at the element integration points ELEMENT PT FOOT E11 E22 E12 NOTE ab 1 2 9952E 08 4 2918E 09 3 0338E 08 1 2 3 1092E 08 8 0920E 09 3 0338E 08 1 3 1 0614E 08 1 5098E 09 3 0338E 08 dL 4 1 1754E 08 2 2904E 09 3 0338E 08 The integration point co ordinates x y are printed next ELEMENT PT FOOT COORD1 COORD2 NOTE L dh 1057 1057 1 2 3943 1057 ay 3 1057 3943 1 4 3943 3943 In the next table the displacements are printed at the nodes uz uy which are free ie not restrained NODE FOOT ul U2 NOTE 27 6 RUNNING ABAQUS VIEWER 1 8800E 08 2 5188E 08 2 3296E 08 4 9401E 08 2 0527E 09 2 1897E 08 2 7304E 09 5 5466E 08 2 1645E 08 2 0987E 08 3 4694E 08 7 7596E 08
18. AE has solid modelling capabilities which may not be as comprehensive as that of a solid modeler such as Pro ENGINEER but never the less may be adequate for most users requirement It also has an option where any keywords which is not yet catered for using the menu based system can be directly typed in using a text editor from within ABAQUS CAE The advantage of doing this within the ABAQUS frame work instead of outside is that the ABAQUS database does not get out of step with the input data Alternatively the user can refer to the ABAQUS Analysis User s manuals and type in the input data file inp in a text editor consisiting of ABAQUS keyword and data lines Section 2 4 gives some simple commands for mesh generation provided within the ABAQUS pro gram itself The PATRAN and FEMGEN programs can be used to generate the data files for structural and ther mal problems However if you require to generate the data file for an analysis in any other specialised field it may not be possible to create the complete input data file ready for analysis You may have to 2 DATA PREPARATION Solid Create Pro ENGINEER Modeler Complex Geometry ascii ascii prt asm Cade HE part assembly ABAQUS Pre PATRAN CAE i Processing T Logfile AA gt C log ascii Y a Printed output Message file ABAQUS a ASS ascii Tes file binary Outp
19. AQUS can be accessed by typing abaqus doc Ignore any warning messages that appear on the window from which the above command was invoked Then click on the Using ABAQUS Online Documentation under the Book Titles section Then click on File Open Book and read any relevant sections Users are recommended to read this part before proceeding further Select the section from the Left Hand Side LHS window See section 3 2 4 on usage of the on line document On line documentation can also be accessed from ABAQUS CAE Start up CAE and then look at the Help menu options 9 1 1 Keywords Click on ABAQUS Standard Keywords and then click on File Open Book There are two ways of using the Keyword part of the on line documentation First is to use the keyword search option Type in the keyword on which you want information in the box marked keyword Then click on the box marked Find This is the most useful if the keyword you are 34 9 1 On line Documentation 9 FAQ AND OTHER INFO searching for is likely to appear in a number of different locations If using more than one word separate these by hypen instead of blanks Also watch out for American spelling of words The second choice is if all the information is likely to be grouped together under a single head ing For example if you want to look at the information for the Drucker Prager Model then select the character D from the left hand side window All the k
20. N Point Section A Definition ocal elite Coordinate Core nor System Constraint L Reference Point Part Instance level Assembly Level Material H Amplitude Physical Constraints Connector Property _ Interaction Property Interaction Initial Condition L Bounda Condition Model Level Analysis Step m Output Database Request reas Output Request Diagnostic Output Request Load Boundary Condition L Predefined Fields History data Figure 5 Model defined in terms of an assembly of part instance 21 2 4 Simple Mesh Generation Commands 2 DATA PREPARATION 2 4 Simple Mesh Generation Commands ABAQUS has some simple mesh generation commands which can be used to generate meshes which are of a regular pattern i e generated by repeating a basic unit Consider a beam which is modelled using five elements and six nodes The end nodes are specified as follows NODE NSET ENDS Ly Diy Que 6 300 0 NGEN Ly TE ds The NODE option starts to read the node numbers and co ordinates The parameter NSET has been included with the name ENDS This will place the nodes 1 and 6 in that group The NGEN option generates the nodes 2 to 5 and calculates the co ordinates assuming equal spac ing between the nodes Similarly the elements are defined as follows ELEMENT TYPE B21 ly Ll 2 element number
21. OSITION INTEGRATION POINT FREO 1 Ss E End Step Data File cantilever inp Figure 5 shows the organisation of a model defined in terms of an assembly of part instance This organisation of the model matches the way models are created in ABAQUS CAE See the section 2 9 1 of the ABAQUS User s manual Volume 1 for a complete definition of an assembly 2 3 Exercises 2 3 1 Exercise 1 What are the changes you need to make to the above input file if the loading is transverse ie normal to the plate in the z direction 2 3 2 Exercise 2 Rerun the above example as a non linear analysis with a higher load and see the effect it has on the frequencies in the second step Make the following changes STEP AMPLITUDE RAMP NLGEOM INC 100 STATIC 0 01 1 0 1 E 5 1 0 kk CLOAD OP NEW G5 2 200 E6 NODE PRINT FREQ 10 U RF NODE FILE FREQ 10 U RF EL PRINT POSITION INTEGRATION POINT FREQ 10 S E STEP NLGEOM Frequency analysis kk FREQUENCY 20 2 3 Exercises 2 DATA PREPARATION An ABAQUS model af Part Haas 4 Mesh Node Set Element Set Surface Local Coordinate System Section Definition Connector Constraint Reference Part Level Model data Node Set Part Instance Element Set t Mesh ERIS H Node Set H Element Set Connector Surface Constraint Local Coordinate Reference SVEE
22. RICAL steady state and transient DYNAMIC FREQUENCY GEOSTATIC HEAT TRANSFER steady state and transient MASS DIFFUSION steady state and transient MODAL DYNAMIC RANDOM RESPONSE RESPONSE SPECTRUM SOILS CONSOLIDATION SOILS STEADY STATE STATIC STEADY STATE DYNAMICS VISCO DYNAMIC EXPLICIT The ABAQUS Explicit module is run when the procedure specified is dynamic explicit For all other procedures the ABAQUS Standard analysis is run All data definitions in ABAQUS are accomplished with option blocks set of data describing a part of the problem definition The user chooses those options that are relevant for a particular analysis Each option is introduced by a keyword line Keyword lines begin with a in column 1 followed by the keyword Example MATERIAL If the option requires data lines they follow the keyword line The syntax of keyword and data lines is defined in section 1 2 1 ABAQUS Analysis User s manual I Keywords may have parameters Keyword lines use the format in which blanks are ignored and the commas separate the parameters Section 2 1 1 deals with node definition and 2 2 1 deals with element definition Parameters are sometimes required for example on the ELEMENT option which introduces a list of element definition the parameter TYPE is required to tell what type of element solid shell beam etc is being defined Many parameters are optional Parameters may have values Ex
23. Ruming ABAQUS 6 9 Arul M Britto May 7 2010 Contents 1 Introduction EL Manuals ve si sed e AER EA UG a E UNE ROR IE EASRA 1 1 1 ABAQUS Standard and Explicit o aa cauaa a oo A A O ARE 1 35 Whereto Start ma ras rn dr dra ION IT Bae ea ete ea TAs Commander dd lt Da 1 5 Suggested Course of ActiON aou S oa ea E A a a Data Preparation ZA UNS a E E E E E E EEE 2 2 ABAQUS Input vico meia She Bek arae A ata ee ee pl A PA Swe Reh ea et Re Son a De i RB SOE SE Pee Exercise TL cage Bag Bog done EM SMe MER GOR BEE WR Sew OS 22y TORTOISE og A Ge eg ee Se ha hae Sele Oe ten MOE RA hc ike Dee 2 4 Simple Mesh Generation Commands l a saaa ee Running ABAQUS 3 1 Running Batch Jo g sors is a Poi Re ie AA a Re a N 9 2 Running Large Jobs se Loog ae a a A ara 3 3 ABAQUS Environment File abaqus_v6 env 2 2 eee 3 4 Checking tor Errors vis tosses fake a BN a la GEE ee 3 5 Killing ar ABAQUS job cio coca dg ic Act as ad A aod a due as 3 6 Checking the License Serveri o racio iaca ci ed Pa es As 3 7 Restarting an ABAQUS R N are co Shut Sakti sd coe Dc SACS ati ee ea ad File extensions used by ABAQUS Printed Output Running ABAQUS Viewer OL Generala ine aba ui anos A E A BID a A IE NEE PRONG AE ade 6 2 Mesh PlOts ana a ien eGR Ra SED Saree eka 6 3 Displacement Plots and Getting Hard Copies 6 1 2 ee 6 4 Contour Plotare ere ot ks A Ra A iTS o q 6 5 SPAT EE Plots uso il a Gra Bae e
24. US is concerned There is no units associated with ABAQUS The user has to choose an appropriate set of units For structural problem the user should decide on units for Length and Force For time dependent problems the unit for Time also has to be chosen Example Length Co ordinates m metres Force N Newtons Time Sec seconds Then all dependent parameters must be specified in a consistent set of units For example stiffness should be specified in N m Pascals and density in kg m If the chosen Length dimension is metres then a thickness of 4 mm will be input as 0 004 Instead if the chosen units was mm then input 4 0 It is not a good idea to select an arbitrary set of units at the beginning and then hope to sort out the results later Example Co ordinates mm Young s Modulus GPa Quantity SI SI mm SI US Unit ft US Unit inch Length m mm m ft in Force N N kN lbf lbf Mass kg tonne 10kg tonne slug lbf s in Time s s s s s Stress Pa N m MPa N mm kPa Tbf ft psi bf in Energy J mJ 10 J KJ ftlbf inlbf Density kg m tonne mm tonnejm3 slug ft Ibf s in 2 2 ABAQUS Input Read through section 1 1 2 ABAQUS USER s manual Volume I for an introduction to the ABAQUS input data file This is essential reading for new users of ABAQUS The input to the ABAQUS program lt job id gt inp or inp contains model data and history data In the rest of
25. ample MATERIAL NAME STEEL This associates the name STEEL with the material definition Any line which has in the first two columns are comment lines Any number of comment lines can be placed anywhere in the data file Use comment lines with explanations liberally wherever necessary When you look at these data files after a while it will be easier to comprehend the data Warning Do not use blank lines as a substitute for comment lines to make the input gt data file more readable Avoid blank lines which could lead to errors K When experimenting with some alternatives some of the keywords and data lines can be taken out of execution by inserting in the first 2 columns These can then be J re activated later by removing the This is easier than first deleting and then having 2 to re enter these lines again Warning Figure 3 shows the simple example problem being analysed Figure 4 shows the finite element mesh used for the analysis Each element is a 4 noded quadrilateral ol 10 2 2 ABAQUS Input 2 DATA PREPARATION The plate is 1 metre square The units for length has been chosen to be metres The force is chosen to be in Newtons The Young s modulus is then specified in N m for consistency The density is specified in K g m 100 N lm Y lm gt X Figure 3 A cantilever example 100 7 8 9 Uy E GB a node E 6 4 gt MD QO Figure 4 Finite Element Mesh The fi
26. and nodes at either end ELGEN ELSET BEAMS Ly Sy ip oh First number is the master element and the second number is the number of elements in the row The third is the increment in the first node number from element to element and the fourth number is the increment in the element number B21 is a linear interpolation element for two dimensional problems ELGEN will generate the element nodal connectivity for all the remaining elements based on the information given with the ELEMENT option All 5 elements are identified by the same set name BEAMS which can then be used to specify the material properties See sections 2 1 1 and 2 2 1 of the ABAQUS User s manual for more examples on the use of NGEN and ELGEN commands NFILL command can be used to generate the nodes within a region using the nodes along 2 lines demarcating that region NMAP command allows one to map nodes from one co ordinate system say cylindrical to an other say Cartesian e NODE NSET ENDS 6 1 0 0 6 300 0 Te e 12 3 4 5 6 FED e G x 6 a ELEMENT TYPE B21 LL a 1 2 a 3 GELGEN ELSET BEAMS 00066005 ARA 2 3 4 5 6 Figure 6 Mesh Generation Commands 22 3 RUNNING ABAQUS 3 Running ABAQUS Before running ABAQUS you will need to set up an input data file called analysis inp analysis is job id and represents the name of the analysis but it must end in inp contains the data for the program Detailed i
27. as applied in a single increment In order to illustrate the X Y Plots the analysis will have to re run as a non linear analysis with several increments The following changes are made to the second step Changes to the output is also made to illustrate some of the features available kk xx STEP pre load kk Step name pre load nlgeom pre loading Static 00d dE Les05 0 1 k xx LOADS kk Name pt load Type Concentrated force Cload 65 2 200 E6 kk kk xOutput history frequency 1 xnode output nset _G5 CF2 U2 xelement output elset _G5 E22 S22 31 6 7 Creating a Force Displacement Plot 6 RUNNING ABAQUS VIEWER Kk xmonitor node _G5 dof 2 The initial time step is changed to 0 01 from 1 0 and the nlgeom parameter has been added to the Step line The loading has been increased to 200 E6 to show that the displacements will be sufficient to illus trate the non linear effect Further history information is added to the output in order to generate a stress strain plot The analysis is run again with the modified data Once the analysis is completed access the odb database as before Step Frame Section Points Field Output History Output Figure 9 Option to change contour type From the main menu bar select Result History Ouput In the History Ouput dialog box Select Spatial displacement U2 at node 9 from the list Output Variable Click on Save As button Enter
28. d so far The following command illustrates the restart option available in ABAQUS 25 5 PRINTED OUTPUT The first part is run as follows abaqus job dynam Then create a data file called dynamr inp and type the following abaqus job dynamr oldjob dynam 4 File extensions used by ABAQUS The ABAQUS program generates several files Some of these files exist only while ABAQUS is execut ing and are deleted as a run completes Other files contain analysis post processing and translation results and are retained for use by other analysis options restarting or post processing A summary of the essential files are listed below the complete list can be found in section 3 5 1 of the User s manual cae The database com Analysis command file has the current job parameter settings dat Printed output file It is written by the analysis datacheck and continue options f User subroutine FORTRAN file fil Results file It is written by the analysis and continue options default binary inp Analysis input file It is read when the analysis and datacheck options are selected log Log file A log of all the abaqus analysis jobs mdl Restart file ctrated by ABAQUS Standard for continuing an analysis msg Message file It is written by the analysis and continue options in ABAQUS Standard odb The results output database used by the Viewer module ps ABAQUS Viewer Postscript output file res Restart file Used for restarting analys
29. e University Engineering Depart ment s Teaching System T S Computers Section 2 of this manual deals with the input to the ABAQUS Analysis module Section 3 sum marises the system dependent commands necessary to run ABAQUS in the Teaching System Section 4 lists the various files created during an ABAQUS run Section 5 summarises the printed output Section 6 deals with the post processing facilities available with ABAQUS Section 7 deals with post processing using the PATRAN program Section 8 deals with how to troubleshoot when you encounter problems Section 9 covers further information on additional manuals examples and ABAQUS FAQ s This handout is mainly aimed at ABAQUS Standard users There is no equivalent handout for the ABAQUS Explicit program ABAQUS Explicit users should consult the relevant user manuals 1 1 Manuals A set of the manuals is available for reference in the Computer Operator s Office Not all the manuals are available in paper form Some manuals are only available on line Example Theory Verification See also the Using ABAQUS On line documentation The on line version of the documnetation is quite comprehensive and up to date 1 1 1 ABAQUS Standard and Explicit 1 ABAQUS CAE User s Manual Getting Started with ABAQUS Interactive Edition Getting Started with ABAQUS Keyword Edition ABAQUS Analysis User s Manual Volumes I II III IV and V Theory Example Problems Manual ABAQUS Benchmarks Problems
30. e of continuum elements shell and beam elements For users who are launching themselves into their first analysis the relevant information for any given analysis is spread over the many ABAQUS manuals You need to read all the relevant sections make notes as you go along and also follow up on all cross references you come across You need to find all the information pertaining to the following topics for your analysis Analysis Type Procedures Element Types Material Behaviour Loading Boundary Conditions Output Only after reading all the relevant information are you in a position to run your own analysis It is a good idea to find an example which is closest to your analysis requirement Chapter 6 of the Users manual deals with the different analyses and procedures This is a good place to start Chapter 17 gives an introduction to the material behaviour Chapters 17 to 22 cover all the material models available in ABAQUS ABAQUS provides a broad range of material models Section 17 1 3 has material model combi nation tables which is helpful in showing which material properties could be combined together and which cannot be Chapter 23 introduces the element types Look through chapter 23 to 25 of the above manual to identify the element types to be used in the analysis This section also has information on the type of loading Chapters 26 to 28 contains information on more non general specialist element types Once
31. ections 2 and 3 and then complete the post processing section 6 Then if you have to make changes to the input data you will have some idea of the structure layout of an input file Then you can work through the tutorials mentioned above Then follow the suggested course of action in carrying out your own analysis 1 4 Commands To find out about all the options that are available with ABAQUS and this will list all the options that can be used when running ABAQUS abaqus help See also sections 3 1 1 3 2 1 to 3 2 27 of the ABAQUS User s manual Volume 1 for more informa tion on execution procedures Section 3 3 1 has examples of using the abaqus command To access the on line information on the keywords more details in section 9 1 abaqus doc To find out which examples make use of a particular key word illustrated here with the keyword dynamic abaqus findkeyword job dynamic dynamic lt CR gt The output will be written to the file referred to by job and with the extension dat ie dynamic dat The analyses data files listed in this file can be obtained using the abaqus fetch command To extract a copy of the input files for the airspring example abaqus job airspring fetch To run the pre processing program ABAQUS CAE abaqus cae It is also possible to submit the job and do the post processing from ABAQUS CAE without exiting from it To run an ABAQUS analysis both ABAQUS Standard and Explicit abaqus job abcd1 To run the pos
32. efine the properties of this material until a keyword appears that does not define material properties such as a STEP option as in this example ABAQUS only uses the material properties that are relevant for the current step and ignores the rest The material behaviour definition can therefore be as complex as needed EXPANSION thermal expansion PLASTIC DENSITY This completes the model part of the data input for this example Rest of the data comprises the history part The analysis consists of 2 steps In the first step loading is applied pre load and in the second step the eigenmodes and frequencies are calculated Step name pre load pre loading Static k Initial Time Step Time Min time and Max time Vi Aer Le 00 Ls xEnd Step The STEP option begins the step the END STEP option ends it A more complex analysis would have several steps and might use the RESTART option to divide up the analysis The line which follows the Step statement will be displayed in the CAE Viewer for this step and acts as a label This is specified when the STEP was created in CAE Which shows that meaningful headers are preferable than the default labels headers Next the boundary conditions are listed The idea is to fix the left hand vertical boundary i e the nodes 1 4 and 7 are fixed in both X and Y directions i e PINNED These nodes form the node set _G4 Boundary _G4 PINNED Kk The general form of the data input c
33. efined Itis empty otherwise Next comes the assembly definition Assembly name Assembly Kk xInstance name plate 1 part plate The assembly is given the name Assembly and this is followed by the instance definition Here the instance is given a unique name plate 1 and the part option identifies the part It is a good practice to name the instance derived from the part name This avoids any confusion However if using CAE this will be done automatically as is the case with this example The NODE option begins the specifying of the nodes and its co ordinates NODE xx Node No X coord Y coord H 0 0 0 2 057 0 First number in each line is the node number and this is followed by the x and y co ordinates Gaps are allowed in the node numbering The ELEMENT option deals with the element nodal connectivity list The element type is specified using the TYPE parameter The choice of element type is as important as any other aspect of a finite element analysis The quadrilateral elements that can be used in a plane stress analysis are CPS4 CPS4I CPS4R CPS8 and CPS8R Here C represent Continuum and PS represents Plane Stress This is then followed by the number of nodes in the element Optional R which follows represents Reduced integration For illustrative purposes the lower order 4 noded elements are chosen here Because bending is involved see the loading and boundary conditions and because of the use of lower order element it is
34. eywords are grouped under the letters of the alphabet Clicking on D displays the start of the sections under the heading D on the RHS Click on the gt symbol next to D and this will open up and list all the keywords which start with the letter D Click on the right pane to bring it into focus and then use the Page down up keys to scroll Alternatively use the vertical slide bar next to the left hand side window to scroll down until you come across Drucker Prager Clicking on that heading will display the relevant section on the right hand side The various sections under this heading can be displayed by clicking on the sign next to Drucker Prager on the LHS window 9 1 2 User Manual Click on ABAQUS Standard User s Manual and then click on File Open Book In this case the heading of the 11 parts see below will be listed on the left pane In the right pane you will find hypertext links ie words which are underlined When you click on these words it will jump to the appropriate section in the manual Because of the numerous links one could easily get lost or go around in circles Therefore it is important to be aware of the relative position within the manual For this reason the chapter headings are listed below The ABAQUS Analysis User s manual consists of 5 volumes The whole manual is divided into 9 parts Each part in turn is divided into chapters When clicking on any links be patient If equations and figures are present
35. is and post processing default binary sta Status file ABAQUS writes increment summaries to this file in the analysis and continue options stt Restart file 023 Communications file used by ABAQUS Standard only This file is written to the same directory as the other user files dat Deleted when ABAQUS terminates 5 Printed Output The dat file contains the printed output If the PREPRINT ECHO YES MODEL YES HISTORY YES option is used in the input file then the printed output consists of a listing of the data in the inp file It is good practice to establish a routine where the first thing you do after the analysis has been completed is to look at the dat file to see whether ABAQUS has interpreted the input parameters correctly Experience has shown that some of the common mistakes can be attributed to either wrong input data or wrong interpretation of the input data by ABAQUS this is only applicable if you have prepared the input file by hand This is not so relevant if the input file was generated by CAE or other pre processing program eg PATRAN If applicable a list of warning and error messages are printed This is followed by several tables for each category of input recognised in the input file starting with the Element definition This is followed by information relevant to the solution This is terminated by the line 26 5 PRINTED OUTPUT x X x Integration Points O Nodes Figure
36. le tab and select the Line tab This option is shown in Figure 8 Basic Color amp Style Labels Shape Limits Other Model Edges Contour Lines Spectrum Interval Style Thickness Line A Banded 5 TAR Figure 8 Option to change contour type Under the heading Contour Lines the sub headers are Interval Style and Thickness The middle row has arrows pointing upwards and downwards Set the interval to be 1 by clicking on the appropriate arrow then set the style and thickness Then increment it by 1 and set the style and or thickness to be different Once the required number of intervals have been set click on Apply This should display the required contour plot with lines of different types 6 5 PATH Plots Consider taking a section along the left hand vertical edge and then plotting the variation oyy along this line This is called a PATH plot where the line section represents the path e From the main menu bar select Tools Path Create In the Create Path dialog box Type vertical for the Name and then toggle on Point list and then click on Continue Here there is a choice of inputting the node numbers to define the line position or defining points by specifying the co ordinates Here the latter option is chosen e In the Edit point List Path enter the co ordinates 0 0 on the first line and press the RETURN Key Then enter 0 1 for the 2nd point and press the RETURN Key Then
37. n a more general problem other instance specifications follows this until all the instance specification is complete End Instance This is then followed by node sets and element sets that may be required for the analysis Nset nset _G4 internal instance plate 1 generate aE Mess 70 Elset elset _G4 internal instance plate 1 Tes Nset nset _G5 internal instance plate 1 9 The first of these creates a node set called G4 containing the nodes 1 4 and 7 The generate parameter means the data line is interpreted as starting node number ending node number increment in node number The second groups the elements 1 and 3 into an element set called G4 Notice that the same name can be assigned to node sets and element sets There is no ambiguity here because the entities are different The last set consists of the node 9 and it forms the node set G5 The assembly specification is completed by the following statement xEnd Assembly The material definition for this example is MATERIAL NAME STEEL Kk DENSITY 7680 kk ELASTIC Young s Mod Poissons ratio 2 1E 11 0 3 13 2 2 ABAQUS Input 2 DATA PREPARATION Here the material is identified by the name STEEL It is isotropic TYPE ISO which is the de fault option 2 1E 11 is the Young s modulus in N m and 0 3 is the Poissons ratio The density is 7680 kg m All keywords that follow the MATERIAL option and introduce material behaviour like ELASTIC d
38. n one of the Teaching System Computers at a low priority at a later time when the demand is not high For the above example type batch mbao ttimelimit 3600 QD abaqus job cantilever interactive The timelimit is set in seconds which is equivakent to 1 hour for this example The progress of the submitted batch job can be monitored using the batchq command Use the batchrm to delete the jobs before these are run if you subsequently change your mind See the man pages on batchq batchrm for further details Example type man batchq The files created by a ABAQUS job will always be placed in the directory from which the abaqus job was submitted However the batch command cannot be used if the input files are in tmp 23 3 2 Running Large Jobs 3 RUNNING ABAQUS 3 2 Running Large Jobs Care is needed when running medium to large size ABAQUS jobs in the teaching system Large ABAQUS jobs should only be run using the gridengine command ABAQUS jobs can be cpu inten sive and resources hungry Give due consideration to other users in running ABAQUS jobs The Computer Operators have the authority to terminate any ABAQUS jobs inconveniencing other users IMMEDIATELY If in doubt check with them before starting a large ABAQUS job For large ABAQUS jobs gridengine is the recommended choice Report any problems to the Computer Operators opera tors eng In addition to the files created in the directory from which ABAQUS is run dat
39. nal instance plate 1 1 3 Nset nset _G5 internal instance plate 1 9 End Assembly k xx MATERIALS k Material name steel Density 7680 Elastic 2 1e 11 0 3 PR SS SS SS SS SAS SS ASS RS SS ASADAS k xx STEP pre load k Step name pre load nlgeom pre loading Static due deg 1S6 05 Ls k x BOUNDARY CONDITIONS k xx Name lhs fixed Type Symmetry Antisymmetry Encastre Boundary _G4 PINNED k xx LOADS k xx Name pt load Type Concentrated force Cload 65 2 100 kk 18 2 2 ABAQUS Input 2 DATA PREPARATION xx OUTPUT REQUESTS kk Restart write frequency 1 kk xx FIELD OUTPUT F Output 1 kk 0utput field variable PRESELECT kk xx HISTORY OUTPUT H Output 1 kk 0utput history variable PRESELECT kk NODE PRINT FREQ 1 U RE NODE FILE FREQ 1 U RE kk EL PRINT POSITION INTEGRATION POINT FREQ 1 S E COORD EL FILE POSITION INTEGRATION POINT FREQ 1 S E COORD End Step xx q O o kk STEP eigenmodes kk Step name eigenmodes perturbation eigenmodes Freguency eigensolver Lanczos Sr rro kk x OUTPUT REQUESTS kk Restart write frequency 1 kk xx FIELD OUTPUT F Output 2 kk 0utput field Node Output U xElement Output S kk NODE PRINT FREQ 1 U NODE FILE FREQ 1 U xk 19 2 3 Exercises 2 DATA PREPARATION EL PRINT POSITION INTEGRATION POINT FREQ 1 S E EL FILE P
40. nstructions for setting up this data file is given in the ABAQUS USER s Manual The input data file can be prepared interactively by running the CAE See the ABAQUS CAE Users s Manual ABAQUS is licenced to run on the Teaching System Linux servers DPO and EIETL It is also available in the twn s locally in the Windows OS ABAQUS cannot be run on the gateway servers After logging into the T S Teaching System Computers HP UX first of all run a window manager example twm amp This is optional To run a ABAQUS Standard or Explicit job with the job parameter is set to the analysis id If you have the input data file called cantilever inp then you can type the following to run the analysis abaqus job cantilever interactive This is recommended for small jobs and during the early stages of a new analysis It will echo the different stages of the analysis and in case of errors will point to which file to look at However it will tie up the terminal until the ABAQUS job finishes Also you cannot log out from that session until the job finishes It writes out the information normaly written the the log file cantilever log file for this example to the screen No log file is created The alternative is abaqus job cantilever This will submit the job to the queue without any prompts ABAQUS will then start running You could monitor the progress of the job by typing tail 10f cantilever log in a separate x term This will tie up the x
41. nt numbers e choose Options Undeformed Shape The Undeformed Shape Plot Options dialog box should appear 28 6 3 Displacement Plots and Getting Hard Copies 6 RUNNING ABAQUS VIEWER Undeformed Mesh Plot Icon e Click the Labels tab Toggle on Show node labels Toggle on Show element labels Click on Apply This should display the mesh with node and element numbers To plot the deformed mesh e From the main menu bar select Plot Deformed Shape or use the icon shown below Deeformed Mesh Plot Icon To plot the deformed shape superimposed over the undeformed mesh e In the Deformed Shape Plot Options dialog box toggle the Superimpose undeformed plot Then click on OK By default the undeformed mesh is coloured green and and the deformed mesh is coloured white To change the the displacement scale factor e choose Options Deformed Shape e In the Deformed Shape Plot Options dialog box click on the Basic tab e From the deformation scale factor region toggle on Uniform and enter 1 0 in the Value field Click on Apply This should display the actual displacement e Now change the value to 1 E6 and then click on Apply To get a displacement vector plot e From the main menu bar select Result Field Output In the Field Output dialog box Select U from the list Output Variable and then click on Magnitude in the Invariant table e This will ensure that the displacement vector both components is selected
42. onsists of the Node number or node set label First d o f con strained Last d o f constrained the magnitude The following input represents this general form Boundary Node set start DOF fin DOF value Gr iZ 0 Kk Here PINNED is a short form However both are equivalent Some of the other useful acronyms are XSYMM YSYMM ENCASTRE Next the loading is listed Here CLOAD stands for Concentrated loads In the line which follows G5 is the nodeset with the node 9 to which the load is applied 2 the direction or degree of freedom and 100 the magnitude in Newtons The minus sign indicates that the load is applied in the negative y direction 14 2 2 ABAQUS Input 2 DATA PREPARATION Name pt load Type Concentrated force Cload xx Node set dir Force Magnitude G5 2 100 K More increments will be needed in an analysis with material non linearity eg elasto plastic be haviour and or geometric non linearity Then add the INC N option with N replaced by a suitable number of increments to the STEP statement Because the eigenmodes under the pre loading state is required this has to be treated as a non linear analysis with large deformation For that include the NLGEOM parameter to the STEP line Then the geometric changes will be accounted for during this and subsequent steps The INC parameter defines the number of increments to be 100 for this example Increments is used to sub divide the total loading in a step
43. ption to continue an analysis then delete the mdl and stt files as well 3 5 Killing an ABAQUS job Care is needed in killing ABAQUS analysis jobs There are two commands available To suspend a submitted job after it has started executing use abaqus suspend job analysis here analysis should be the same for the previously submitted job whch is being suspended To kill the analysis use abaqus terminate job analysis To resume a previously suspended job abaqus resume job analysis Do not routinely use the command kill 9 lt process id gt to kill currently running ABAQUS jobs It should only be used as a last resort if other options to kill off any abaqus jobs have failed Here lt process id gt is the process number of the ABAQUS job The list of process ids which would include the ABAQUS job can be found using the command ps eaf grep lt your user id gt 3 6 Checking the License Server To check whether the ABAQUS License Server is running use the abalicence command This is not a part ABAQUS but is a local command which makes use of the Imstat command and consists of the line abaqus licensing Imstat S ABAQUSLM 3 7 Restarting an ABAQUS Run The restart option is quite useful to break up a long abaqus run into a series of smaller jobs Each such job will continue from the end of the previous job This option is also useful if you want the change some parameter or rate of load application depending on the results obtaine
44. rements in a step then N can be set to 10 The results will only be written to the restart file at the end of every 10th increment Alternatively if you are only interested in restarting the analysis at the end of the current analysis then you can use the following command RESTART WRITE OVERLAY This will write the results at the end of every increment after rewinding the restart file At the end of the analysis the res file will contain only the results of the last increment If the analysis is interrupted for some reason then it will contain the results of the increment which was completed just prior to the interruption If necessary the analysis can be continued from the increment written to the restart file ABAQUS includes default output requests these provide the necessary information of element variables stress strain etc and nodal variables displacements reaction forces which are used for post processing using the Viewer module In general users may request output of variables at locations nodes element integration points that are of interest to them The complete list of variable names can be found in section 4 2 1 of the USER s manual Volume I 15 2 2 ABAQUS Input 2 DATA PREPARATION A list of the PRESELECT variables for each type of procedure is listed in the table 4 1 3 1 in the USER s manual Volume I Here part of the table for static and frequency procedures have been reproduced below
45. rst option is usually the header for the analysis this is given on the HEADING option The next line will be taken as the heading and this will appear on each page of the printed output dat file when ABAQUS has run It is a good practice to include a line explaining the units being used for length and force as part of the heading HEADING SQUARE PLATE SUBJECTED TO POINT LOAD Job name cantilever Model name Model 1 xx Units Length m Force N Stress N m2 Time Sec The next parameter PREPRINT is optional 11 2 2 ABAQUS Input 2 DATA PREPARATION Preprint echo YES model YES history YES By default this is omitted which is same as including it with all 3 options set to NO This is useful for debugging purposes More on this later In ABAQUS the finite element model is defined as an assembly of part instances Part instances are the components of the assembly Where parts are defined as the master components The instances are copies of these This permits re use of the parts If an assembly consists of some components which are identical then these components have to be only defined once as a single part Then there should be equal number of instances of this component representing each of these item For the example under consideration the assembly is made up of a single part with a single instance of that part Part name plate End Part This represents the part definition It simply has the name plate d
46. set hats ek Woes genres ake Wes Mahe Wan ec A 6 6 XY Plots cs hte i he ON EES ROSE atk A ES cag AAS 2 6 7 Creating a Force Displacement Plot aa aaa 6 8 Writing Out Results o se ora e eae a ee A Aw eee E A a CONTENTS CONTENTS 7 Post Processing using Third Party Programs TL Geriefal 3 breach se ot Eee ack VE 7 2 Post Processing using PATRAN o oo 8 Troubleshooting 8 1 N Message Pile cens gy E a ate a Men 8 2 Blank pages instead of Plots for hardcopy 89 BUES n a A AMPA Mae O o R 9 FAQ and Other Info 9 1 On line Documentation o e e 91 1 Keywords s swa os o ee a eS 912 User Mandala sek oie ee es 1 INTRODUCTION 1 Introduction ABAQUS is a general purpose finite element program distributed by ABAQUS Ltd It has a large element library and is capable of analysis of a variety of problems linear nonlinear static dynamic structural and thermal ABAQUS CAE is an interactive graphical for running ABAQUS Post pro cessing is provided by a separate module known as the Viewer The main aim of this manual is provide an overview It does not provide any instructions on how to run the CAE module This has been covered extensively elsewhere However essential use of ABAQUS Viewer is covered but by no means comprehensive The remainder of this section deals with the manuals the commands to run the various modules and how to go about running an ABAQUS analysis in the Cambridg
47. sing PATRAN See the next section on how this is done 7 2 Post Processing using PATRAN See the PATRAN beginner s guide on how to use the PATRAN program to post process the abaqus results stored in the fil file Type patran to start running PATRAN If you had used the PATRAN program to generate the inp file in the first place then section 10 of the above guide explains how to generate the plots on the screen and how to produce the hard copies of the generated postscript files However if the inp file was not created using PATRAN then you need to follow the instructions in section 2 How to start a PATRAN session of the above guide Create a new database of the same name as the analysis you have just run Change the template to abaqus db and then follow the instructions given in section 9 of that guide But choose Read both instead of Read Results for action This means that instead of reading only the results you need to read both the results and model data This is because PATRAN needs the information about the model mesh as well as the mesh was not generated using PATRAN Then follow the instructions given in that guide 33 9 FAQ AND OTHER INFO 8 Troubleshooting 8 1 No Message File ABAQUS run has finished and the msg file is missing Error must have occurred during the pre stage of the ABAQUS run This may be due to errors in data detected by ABAQUS The dat file does not have a s
48. t processing program ABAQUS Viewer abaqus viewer To create an executable module from a user written Fortran program prog1 f this would create prog1 x 1 4 Commands 1 INTRODUCTION Create complex ABAQUS fe N Pre lt _ gt cae Geometry CAE A Processing binary ascii G MN pt AA ale verano ra Cp Message file Printed output msg dat ABAQUS P oe Analysis Ss a a y ascii X LES 3 Restart binary file G Opt O tres odb Output ASS Database binary ABAQUS Be MT Viewer 7 Processing R e srs oa epresents files which are identified by the extension names PS Postscript files Figure 1 ABAQUS CAE ABAQUS Viewer and the Analysis Module 1 5 Suggested Course of Action 1 INTRODUCTION abaqus job abcd1 make user prog1 To run the executable module created using the make command abaqus prog1 x To run MSC PATRAN patran For other ABAQUS commands see section 3 1 1 of the User s manual Vol 1 Section 3 3 1 has examples of its use 1 5 Suggested Course of Action e New users are recommended to read through sections 1 1 1 amp 1 2 1 of the Analysis User s manual volume I Section 1 2 2 deals with conventions and units The Getting Started with ABAQUS Standard manual is the best starting place for new users It has examples on linear non linear dynamic plasticity and contact problems It also has a good introduction to the us
49. teps and increments Then the turnaround time while you debug the data and root out the errors will be shorter Once you familiarise yourself with ABAQUS you can refine the mesh and add complexity to the analysis In order to familiarise oneself with the 6 9 style format of the input file section 2 9 1 Defining an Assembly in the Analysis Users s Manual Volume 1 is recommended reading This is essential reading only if you need to make changes to the input file created by CAE using a text editor This is again if you are using features keywords currently not supported by CAE 2 Data Preparation Figure 2 shows the various ABAQUS modules and the inter relationship between PATRAN Pro ENGINEER programs and ABAQUS As shown in this figure the ABAQUS input data file inp can be created by PATRAN interactively It is also possible to use the mesh generation commands available in ABAQUS section 2 4 If you are working with complex and or 3 dimensional geometries use of either PATRAN or FEMGEN is recommended Complex 3 dimensional geometries can be created in Pro ENGINEER and imported into PATRAN and then meshed before a ABAQUS analysis It is also possible to use the new ABAQUS CAE mod ule which provides the capability of both a solid modeller Pro ENGINEER and a pre processor PA TRAN However because CAE is relatively new it does not as yet cater for the full capabilities offered by the analysis modules ABAQUS Standard amp Explicit ABAQUS C
50. term in which the command was typed When the run has completed use CTRL C to free that x term ABAQUS will produce a number of output files during its run these are listed in section 4 Whenever you run an ABAQUS analysis look at the log file first If you use the interactive option then the contents of that file will be directly printed to the screen and the log file not created In case of errors it will tell you which file to look at Look at the msg file for possible errors and warning messages In the absence of the msg look at the dat for any error messages and the end of the dat file for the summary Note that dat can be large Use the tail command to look at the last few lines as shown below tail 50 cantilever dat This will list the last 50 lines in that file If the name of the data file inp is known after consulting either the examples manual or the verification manual then the data file can be obtained using the fetch command For example to get the input data for Detroit Edison pipe whip experiment input type abaqus fetch job detroitedison This will fetch the detroitedison inp file It is also possible to get a copy of the input file using cut and paste from the on line copy of the ABAQUS Input files and the Verification Manual using abaqus doc 3 1 Running Batch Jobs During term time and when running large ABAQUS jobs the users are recommended to use the gri dengine This will execute the ABAQUS jobs o
51. tricts the output to the nodes in that set NODE PRINT FREQ 1 U RE To print the displacements and the reactions in a single table use the above commands NODE FILE FREQ 1 U RF This writes out the nodal displacements U and the reaction forces RF to the fil file for post processing using PATRAN or FEMGV Latest version of PATRAN 2003 R2 can also make use of the odb file ABAQUS output database for post processing EL PRINT POSITION INTEGRATION POINT FREQ 1 ELSET _G4 S E COORD 16 2 2 ABAQUS Input 2 DATA PREPARATION This writes out the stresses S strains E and co ordinates COORD at integration points to the dat printed output file It is also possible to write out the stresses and strains averaged at node by specifying POSITION AVERAGED AT NODES If using this option then omit COORD from the parameters to be written Similarly interpolated values at element centroids can be printed using POSITION CENTROIDAL Here again the output is restricted to the elements in the set G4 EL FILE POSITION INTEGRATION POINT FREQ 1 S E COORD This writes out the stresses S strains E and co ordinates COORD at integration points to the fil file for use with user written post processing programs The number set by the FREQ parameter 1 in this example is the output frequency in terms of increments Use the FREQ 0 option to suppress information being written to the fil file in the above example
52. tton and name the plot as Force Disp Nde9 Click on OK e Then Click on Plot Expression button and this should display the Force Displacement plot 6 8 Writing Out Results from X Y Curves to an External File This section deals with how to write out the results from an X Y Curve Example the force displace ment plot results created in the previous section From the main menu bar select Report XY In the Report XY Data dialog box toggle on XY Plot in the Current Viewport That plot will be highlighted Click on the Setup tab and the name of the file to which the results will be written to is displayed as abaqus rpt This is the default fiel name If the current results are to be appended to the existing contents make sure the toggle Append to File is ON It is also possible to control the format of th results from the settings in this dialogue box Once you have altered the settings to suit your requirement click on OK Use a text editor to check the contents of the file It should be straightforward to import this into a spreadsheet and produce plots comparing either with available experimental or theoretical results 7 Post Processing using Third Party Programs 7 1 General Once the odb file is created one can use ABAQUS Viewer to post process the results PATRAN may not recognise some of the specialist element types piezoelectric semi infinite For more general problems the odb can be used for post processing u
53. ummary at the end Probably your disk quota has been exceeded Type quota v and check your quota See also section 3 3 8 2 Blank pages instead of Plots for hardcopy ABAQUS CAE Viewer is producing blank pages when plots are sent to the DPO printers ljmr1 ljmr2 Saving the plots as postscript files and then printing also gave blank pages Add the oraw option to the print command Example lp oraw ljmr1 abaplot ps For more information see the ABAQUS web page under Computing Help 8 3 Bugs Up to date information on any bugs in the ABAQUS program can be found in the status reports See the ABAQUS Ltd Home page Search for the occurrence of the keyword you are interested in These error numbers will be preceded by v69 to indicate in which version the bug was found If the bug had been fixed you will find in which version the bug had been fixed The versions installed on the teaching system is version 6 9 1 and 6 9EF The version available in the teaching system is updated once a year 9 Frequently Asked Question FAQ and Other Information In the CUED web page look under Help Engineering Packages Finite Elements ABAQUS for a list of Frequently Asked Questions FAQ and answers Work is currently under progress to set this up Consult the SIMULIA home page accessible from the above page regarding ABAQUS newsletters and product development information 9 1 On line Documentation On line documentation available with AB
54. ut database odb binary Results binary file 0 eatecties Y ABAQUS Post PATRAN Viewer Processing other formats other formats Modules C Represents files which are identified by the extension names PS Postscript files Figure 2 ABAQUS PATRAN and Pro ENGINEER Programs 2 1 Units 2 DATA PREPARATION create the datafile for a standard structural or thermal problem and then write out the inp data file Then edit this file using a text editor and make the necessary changes to the element types material properties by referring to the ABAQUS manuals and then submitting an ABAQUS job Section 2 2 explains what constitutes an ABAQUS input data file for a simple static analysis of a structural problem The input data file is illustrated for a simple example Type patran to run the PATRAN program See the Beginner s Guide to PATRAN on how to use the PATRAN program Type femrun to run the FEMGV program See the FEMGV User Manual on how to use the femgen program A training guide is also available See also the CUED web pages under help Engineering Packages finite elements Pre and Post Processing for more information on either of these programs 2 1 Units A question often asked is what units does ABAQUS use The answer is it does not use any particular units Another question asked How does one set the units in ABAQUS The answer is you cannot set the units Input parameters are simply numbers as far as ABAQ
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