User`s Manual
Contents
1. 0 If friction is accounted for 0 then the wind angle distribution will vary as described in later sections 2 1 Geodesic Dome The geodesic shaped dome is a specially shaped dome which results in a constant strain state along much of the fiber as it wraps around the dome The shape of the dome is directly related to the vessel radius and the wind angle of the layer at the tangent line The wind angle defining the geodesic dome shape is specified in one of two ways Firstly a base wind angle may be specified directly from the Dome Geometry tab as shown in the figure below Secondly if the base wind angle has not been specified then the wind angle of the first helical layer defined under the winding Layout tab is used to determine the geodesic shape MM Edit Wound Composite Dome Name WoundComp 1 Note 4 part will be created with this name Wound Dome Geometry Dome Mesh Controls Dome Dome Geometry Geometry Cylinder Geometry Winding Geodesic Dome Parameters Layout as Vessel Radius Rv 10 O Base Wind Angle in Degrees Figure 2 1 1 Geodesic Dome Input For example Figure 2 1 2 shows a dome in blue which is constructed from a base wind angle of five degrees even though the first layer has a wind angle of ten degrees Had the base wind angle not been specified the ten degree wind angle would have resulted in the shape of the gray dome Figure 2 1 2 Geodesic Dome with without Base Wind2. Laver Termination Nat on End Cap 2 Move to Transition Point 14 Figure 3 5 1 Layer Termination Options in Wound Composite Dialog Transition Ponts Figure 3 5 2 Layer Termination Options 3 6 Layer Level Controls Controls at the layer level are available for each layer type The controls can be grouped in three categories end controls mesh controls and CAD data fitting controls The CAD data controls are used for wind angle and band width curve fitting and are only applicable to helicals or hoops with friction If the Parameters above button is selected then the shape of the layer is determined from the attributes provided and any CAD data is ignored If the Least Squares frit of Cad Data button is selected then a least squares fit is used to determine the curve exponent and the band width factor A least squares fit is not yet available for the extrapolation fraction so a default of 0 5 is used Therefore the parameter based curve should fit the CAD data throughout the length of the dome except possibly near the end of the layer 15 Layer Data CAD Data Mesh Controls Friction Layer Information Layer Number 1 Current Layer Radius 10 0 Winding Quantities Wind Angle 5 0 Inner Radius Curve Exponent Band Width Factor 1 0 Create geometry From Parameters above C Least squares Fit of CAD data Directly From CAD data End Control Parameters End Type
3. Horizontal Position 1 Diameter 1 Wind Angle 1 degrees Thickness 1 Horizontal Position 2 Diameter 2 Wind Angle 2 degrees Thickness 2 The diameter is defined as the diameter at the interior of the layer The exterior of the layer is determined by first generating a vector which passes through the point and is normal to the mandral Using the thickness and this normal a point on the exterior of the layer is calculated 5 1 Sketch of CAD Data The first step in creating a model from CAD data is to first read in the CAD data and convert the raw CAD data into a sketch in order to diagnose any potential problem areas This done by selecting the Plug Ins WoundComposites Import CAD Data item under the plug in drop down menu Select the Sketch Raw CAD Data toggle and submit the dialog Another dialog will appear in order to select the mandral and layer files as described above Creating a sketch with straight lines between every CAD data point would be a very slow process because the constrained sketcher would create a constraint at every data point An alternative is to draw the data points with a spline In this case the constrained sketcher only creates constraints at the beginning and end of the spline The intermediate points are used in the sketch but are not visible when viewing or editing the sketch The result is a sketch which is much faster to generate However any discontinuities in the normals of the surface will be smoothed out t
4. 2 4 shows an example of this After the initial import of the CAD data the bandwidth of individual layers can be modified if desired These high angle helicals are set to the HOOP layer type 38 5 2 2 Ends Abutting Polar Boss The CAD data usually does not exactly define the exterior of a layer which abuts the polar boss For this reason during the import of the CAD data the user must select which layers will abut the polar boss The NONE_VERT end type will be applied to these layers All of these layers will terminate at the polar boss radius defined via the mandral file Even if the adjustment due to band width extends beyond the polar boss radius the layer will be forced to terminate exactly at the polar boss radius CAD Import Layout Tank Materials Default layer material T1000 v Default resin material Resin sin vw Wound Layers Layer Wind Abutt En Boss Number Angle Thickness n ONE VERT 1 ag zoll D 804475 12 632114 0102454 00 270133 0 004403 ed oot 7 0101332 3o 0 616694 oo 90927 0 60445 46 951566 0 6290668 00 391420 0 004441 9 394652 0 622706 Active D D m tf E OF Pl ls li ls E ERES M Figure 5 2 2 END Data Import Table 5 2 3 Tank Creation Upon submission the CAD Import dialog the layer data is sorted and assigned to a dome Checks are made to determine if the tank is symmetric If so a single dome is applied to both the top and bottom of the tank As a default an axisymme
5. Angle For a given wind angle the helical turns around at a radius equal to the vessel radius at the tangent line times the sine of the wind angle For a radius less than this so called turnaround radius the shape of the dome is extrapolated out linearly from the slope at the turnaround radius The figure below shows what this might look like Figure 2 1 3 Layer Extending Beyond Geodesic Turnaround Radius 2 2 Elliptical Spherical Domes Creation of elliptically and spherically shaped domes is available by specifying the vessel radius at the tangent line and in the case of the elliptical dome the radius of the ellipse in the y direction minor axis Figure 2 2 Elliptical and Spherical Domes 2 3 User Defined Dome Generally shaped domes may be defined by providing a list of x y coordinate pairs outlining the shape of the dome A portion of the dialog is shown in Figure 2 3 Right clicking on the mouse while the cursor is positioned in the table will bring up a list of options which includes the filling of the table by reading from a file The text file must contain two columns of numbers separated by either a comma or a blank space The coordinate pairs may be listed in either ascending or descending order based on radius or position along the tank axis The plug in will automatically convert the order of the coordinate pairs in order to create a top or concave dome When the domes are chosen as the top or bottom of the tank then the p
6. a non default curve exponent of 0 1 Er ctionless1 Frictioniess2 Fri ction n 0 1 Eriction nz1 0 Wind Hn ala Theta2 Theta1 R4 R2 Ru Dome Radius Figure 3 6 3 2 This exponent can be manually entered as shown in Figure 3 6 3 2 By selecting the Least Squares fit of CAD Data button the plug in uses a least squares fit to determine the curve exponent n and bandwidth factor which best match the CAD data Winding Quantities 1z2 632114 eb lrz281 5 3 Dn 0 01 Create geometry From Parameters above Least squares Fit of CAD data Directly From CAD data Figure 3 6 3 3 Layer With Friction Data Controls A plotting utility has been made available from within the layer controls dialog This provides a means of immediately determining the quality of the wind angle fit that will be used by the plug in The plot can show 20 the frictionless curve the curve with friction and the actual curve used for the CAD data fit An example of a plot is shown in Figure 3 6 3 4 E Wind Angle Plot A CAD Data Curve Exponent With Friction 5 00 Frictionless 2 617 i 5 585 10 41 11 971 1E 1 Turnaround Vessel Radius Radius Figure 3 6 3 4 Wind Angle Plot of CAD Data 3 7 Dome Level Mesh Controls Dome level mesh controls are available from the MESH CONTROLS tab on the Wound Composite Dome dialog The dome level mesh controls are applied to all
7. are also specified from the Wound Composite Manager dialog Just as is the case with the creation of the domes the creation of the entire tank may require more than a single iteration For this reason toggles are added to turn off the creation of the mesh and the element by element material property assignments since these two operations take the bulk of the model creation time Once satisfactory tank model geometry is generated then the mesh toggle may be turned on and iterations of the mesh can be performed After obtaining a satisfactory mesh then the Regenerate Properties button is pressed the a full run ready model is created Alterations to the model can be made within Abaqus CAE outside of the plug in Some guidelines are provided in Section 4 6 3 on making changes to the model created by the plug in without invalidating it 2 Underlying Dome Geometry A number of different underlying dome geometries are available from the Dome Geometry tab of the plug in While the shapes may be different all may have a cylinder attached and all have a helical winding pattern described by the following equation m E R Ro Y O R sin c pac R Ru Ro Equation 2 1 Wing Angle Definition Here R is the radial distance from the center line to a point in the layer R is the radial distance from the centerline to the turnaround point and Ry is the radius at the dome cylinder tangent line A frictionless winding pattern is obtained by choosing
8. bounds the with friction curve between two frictionless curves The first curve is frictionless curve based on the wind angle given The second curve is the frictionless curve based on a wind angle that would reproduce the turnaround given The difference in wind angles 6 between the two curves is simply ramped down linearly for n 1 0 over the length of the layer with the turnaround specified by the user The resulting with friction wind angle curve is shown in red in Figure 3 1 3 11 Theta2 Theta Ry R gt R Dome Radius Figure 3 1 3 Wind Angle With Friction 3 2 Doily Layer The DOILY type layer consists of a washer shaped ply which is wrapped over other layers as shown in Figure 3 2 A doily is constructed with a uniform thickness and usually of an orthotropic material The primary material direction is rotated from the meridional axis of the tank by the value of the wind angle For example a wind angle of 90 0 degrees results in the primary material direction of the doily being in the tank s hoop direction The doily geometry is defined by giving an inner and outer radius The plug in determines which layers it overlaps and generates any voids if it overlaps the end of another layer Figure 3 2 Doily Layer in Blue 3 3 Hoop Layer The HOOP type of layer is a uniform thickness layer which begins at the base of the dome or in case of an attached cylinder the base of the cylinder and terminat
9. layers of the dome The number of elements through the thickness along with the seed constraints which are shown in Figure 3 7 1 can be overwritten at the layer level 21 Dome Mame WoundComp 1 Note A part will be created with this name Mesh Generation Generate Mesh Quad Quad dominated Tri Mesh Size Number of elements through each layer Mumber of elements along length of dome 300 Global Mesh Seed Contraints allow Ehe number of elements to increase or decrease Allow the number of elements to increase only C2 Do not allow the number of elements to change Global Mesh Partitioning Include partitioning Max number of mesh partitions las Bias Eo Bias Eo Inner Radius Outer Radius 50 Bias Mesh Partition Locations Figure 3 7 1 Wound Composite Dome Level Mesh Controls The mesh partitioning options allow for the creation of partitions through the thickness of a layer all along the length of the layer The spacing of the partitions can be biased toward the top of the layer the bottom of the layer or evenly spaced throughout the layer The partitions control the mesh in a couple of ways Firstly they prevent the mesher from creating skewed elements as shown to the left in Figure 3 7 2 A mesh modified with partitions is shown to the right in Figure 3 7 2 Secondly they allow for the application of mesh seeds and constraints through the thickness all along the length of the lay
10. of commercial finite element codes are inadequate to model the variation of fiber orientation in a practical way Thus the Wound Composite plug in for Abaqus was warranted This Wound Composite Modeler for Abaqus plug in was developed to analyze a wide variety of axisymmetric or three dimensional wound composite pressure vessels This documentation describes the capabilities and usage of the plug in Figure 1 Composite Overwrapped Pressure Vessel 1 1 Plug in Overview The Wound Composite Modeler for Abaqus plug in is a vertical application which is designed to facilitate the creation of an entire axisymmetric or three dimensional finite element model of a composite overwrapped pressure vessel COPV The model created may consist of a single dome and thus a symmetry plane or consist of a top and bottom dome which provides for a full representation of the tank The plug in automates the creation of the tank geometry and its corresponding mesh element by element material property assignments load and boundary condition assignments The resulting model will be run ready all from a single set of dialog boxes The process of creating a COPV model consists primarily of two steps The first step involves creating one or more wound composite domes The wound composite domes are essentially axisymmetric templates of the top or bottom of the tank and are used to create the full tank The second step involves selecting the domes to combine into a si
11. redundant section properties and that the last section property will be accepted This is the expected behavior 4 6 2 Uvarm Subroutine Since the material properties of the fiber have been smeared and transformed into axisymmetric coordinate system output quantities such as stress and strain are not readily available along the fiber direction For this reason a toggle has been added to allow the creation of a UVARM subroutine which facilitates the calculation of material properties along and transverse to the fiber direction An output request is automatically generated requesting Field Output for the corresponding UVARM variables By default the plug in creates five UVARM output variables for axisymmetric shell and continuum geometries which are the wind angle UVARM1 the strain along the fiber direction UVARM2 the strain transverse to the fiber direction UVARM3 the stress along the fiber direction UVARMA the stress transverse to the fiber direction UVARM5 Because we have the logarithmic strain in the pressure vessel coordinate reference frame and we know the wind angle at each point along the dome we are able to rotate these strains into a fiber direction coordinate reference frame For three dimensional analyses additional terms are added for fibers at the negative of the wind angles Specifically the output variables are the wind angle UVARM1 the strain along the fiber direction in the positive wind angle direction UVARM2 th
12. to a single node to constrain the tank Wound Composite Vessel Mame WeTank Tank Domes Ii Geometry Space l Section Assignment Model Generation Thermal Loads F Curing Temperature 0 Room Temperature n Pressure Loads MEOP Max Expected Operation Pressure 100 Create meop load in step Step 1 Displacement Boundary Conditions O No BCs Symmetry BCs 33 Figure 4 4 Loads Assignment 4 5 Mesh Creation The next tank information to be specified is the number of elements to be generated along the length of the tank A toggle is provided to turn off meshing This is useful when generating large models thus allowing multiple passes of geometry meshing while skipping the very time consuming step of meshing the part The number of elements specified is assigned as the total number assigned to the top and bottom domes The number assigned to each is specified to generate equal length elements along both domes Mesh Generation Generate Mesh Mumber of elements along length of tank Figure 4 5 Mesh Generation Inputs 4 6 Job Creation With the domes assigned the number of elements specified and the loads chosen all that remains is to choose to generate the material properties and output if desired Figure 4 6 shows the options associated with these under the MODEL GENERATION tab Include File Creation Generate material and section properties Group properties by F
13. ES UD FOULING duode odisea E e aia 35 4 7 Externally Made Changes to Model esses nnn snis 36 5 Model Creation Ttrom CAD IMPON deu uus eo si lla oralidad dd 37 Stoke CNO P b NEN 37 5 2 Import Ol CAD Dala 37 o A A LI ELA 38 902 2 ENGS ADUHNO Pola BOSS t setenta s opi tue Pula demas tectae s dualis a poet cube Res es 39 52 5 Tali Creado euo dete a ps 39 5 2 4 Tank Geometry Validation asa it dt dai 39 5 2 5 Diagnosing Problems with CAD IMpOlTt c occocccoccccnncncoccncnncccoconnnnononcnnnnnnnonnoncnnnnnnrnnnnnnonninannanonos 40 O DUIPUEPFOCOSSINOO 0 serm com oae diee A ds iaa 40 An eee abate nines tei nctehues tol eo eed da i a Nat ats tee cates toi 43 8 Installation O PIO A o ES 44 9 Refer ONCOS RE DL m MEN 45 PADOTS eea ELO S DU EE 45 Abadus helererio eS ee a a isl e e Ra d Meca ui A i ue 45 1 Background The process of filament winding has become a popular technique in a wide variety of industries for creating extremely high stiffness to weight structures Aerospace industry applications include rocket propellant tanks and solid rocket motors casings Automotive industry applications include high pressure fuel storage tanks for hydrogen powered automobiles The difficulty in accurately analyzing the behavior of filament wound structures derives from the varying orientation of the wound filaments throughout the structure The standard capabilities
14. Figure 6 3 using a smoothing factor of 10 0 This automated path plot utility will not work as expected on models using axisymmetric shell three dimensional shell and continuum shell elements 40 MM Create Path Plots Data Extraction Model shape Deformed shape 2 Undeformed shape COverwrite Paths if they already exist Smoothing Factor 1 Choose wound composite path sets LAYERO1 SESOO PATH LAYERDZ SEGOO PATH LAYEROS SEGOO PATH LAVERO4 SEGOD_PATH x Values 5 True distance O distance C3 Normalized distance Y distance C Sequence ID Y Values Step 0 Step 1 Frame 1 Field output variable Ll UZ Figure 6 1 Path Plot Dialog 41 o e e e Wind Angle S S 20 00 0 00 5 00 10 00 15 00 20 00 25 00 30 00 Position Figure 6 2 Plot of Wind Angles LAYERO08 No Smoothing LAYEROS With Smoothing 6 0 8 0 10 0 True distance along path 0 0 2 0 4 0 Figure 6 3 Path Plot with and without Smoothing 42 Figure 6 4 Wind Angle Contour Plot 7 Sample Test Cases A number of QA problems have been included with the plug in Since these tests are fairly small but test all of the plug in functionality it is recommended that these be run and experimented with in order to familiarize oneself with the workings of the plug in Multiple tests may be selected to be run at one time Three test modes are provided e Skip Material Calculation
15. Files must have Ehe Form name pln m plv case insensitive where name arbitrary string same for all layers n layer number m arbitrary string may differ For each laver Layer Controls Cad Data position defines Center of band C Edge of band Layer Bandwidth 20 0 Figure 5 2 CAD Data Import Table 5 2 1 Band Width Settings When importing CAD data the band width must be known for a couple of reasons First the positional CAD data may be measured from the center of the band or from the innermost edge of the band If the position is measured from the center of the band then the inner most point of the layer turnaround radius must be adjusted by half of the band width The plug in must fill in this missing shape lt does so by tapering the layer thickness down to zero over a length equal to half the band width This is done for all layers unless they are specified as layers abutting the polar boss as described in the next section For high angle helicals above 85 degrees the distance over which the end thickness is tapered to zero must be modified If one half of the width were used to sketch the tapered end region of the layer the result would be a long skinny taper which would require a very fine mesh Instead the band width of the layer is set to a three times that of the thickness at the end of the layer This allows for a more reasonable transition and a coarser mesh to be generated around the layer ends Figure 5
16. NONE _VERT v void Fraction D 5 wf 5 0 E Extrapolation Fraction 0 2 lt ef lt 1 0 03 Figure 3 6 Layer Level Controls 3 6 1 End Controls Five different end types are available for each type of layer The FILLET SPLINE and NO_VOID end types permit the user to specify an end fraction which controls how abruptly the end is rounded off The NONE and NONE_VERT end types do not round off the end of the layer 16 SPLINE ci FILLET NO VOID NONE NONE VERT Figure 3 6 1 1 Layer End Types The NONE VERT end type is used for butting up the layers vertically against a polar boss Layers with this end type may be stacked upon one another terminating at the same radius as shown in Figure 3 6 1 2 This option is used primarily with dome geometries defined from an existing part instance Figure 3 6 1 2 Layers Abutting Polar Boss via NONE VERT End Type An additional end type CAD DATA is available only for models which are generated by importing CAD data The type of these layers is set to either HELICAL FRIC or HOOP and is determined automatically upon import Upon import the user chooses to either set the end type of each layer either to CAD DATA or NONE VERT In either the case the end geometry will be modified depending on whether the CAD data is defined and the center or edge of the band Band InFormatian Cad Data position defines Center of band C Edge of band la Layer Bandwidth el Boss Rad
17. Wound Composite Modeler Also if an error occurs while generating the geometry of the layer the layer gets deactivated and the plug in continues on to the next layer It may help to regenerate the dome geometry in question and deactivate all of the layers after the one having problems This may help to understand what may be causing the geometry to fail such as sharp changes in the exterior of the plies 6 Output Processing When the plug in generates the COPV model it automatically generates node sets named Layern along the bottom of each layer where n is the layer number The dialog accessed from the menu item Plug Ins gt WoundComposites gt Plot automates the process of creating path plots along the interface between layers using these node sets The dialog is shown in the Figure 6 1 For each layer selected from the table the script first details the elements only in that particular layer then sorts the nodes in the Layern node set from one end to another and creates an x y curve of the chosen field variable along the list of nodes Finally all of the x y curves are combined into a single path plot as shown in Figure 6 2 The field output variable step number and frame number must be selected prior to opening up the dialog An option to smooth out the curves is provided The path plots can often contains significant spikes in regions where on layer overlaps another The Smoothing Factor option simply smoothes out these spikes as shown in
18. Wound Composite Modeler For Abaqus User s Manual Ei Edit Wound Composite Dome Name WoundComp 1 Note 4 part will be created with this name Wound Dome Geometry Dome Mesh Controls DS SIMULIA Abaqus Version 6 7 3 2007 SIMULIA Inc Dome Winding Layout Controls Geometry Cylinder Geometry Layer Termination O Not on End Cap Move to Transition Point Winding Layout Winding Layout Void Material Material Name Resin v Active sidad Material 1 HELICAL_FRIC T1000 2 DOILY T700 3 HOOP T700 4 HELICAL NOFRIC T1000 5 HELICAL FRIC T1000 Thickness 0 05 0 05 0 04 0 05 Wind Inner Duter Hoop ved Angle Radius Radius Height Factor 5 0 0 5 1 90 0 2 0 5 0 90 0 40 0 74 0 5 2 0 a Item is not applicable to assigned layer type Table of Contents 1 BACKI MORD D UI T UN Ein Ce ere L eee eee eee eer ere 3 ds AO LEEREN 3 ZURdetiyind Dome Geometria ias 5 Eo AA m T I m 5 2 2 Elliptical spherical DOMES sdb uet oie Qoae edet cd ost e demde desse eivai ededece tart asage ca esp c PEE p ne RE 7 2 3 USE rDENACA DOM ii A A a ne oa oils 7 22 FOME art Instance DONE A Sid 8 2 9 4OVlifider GOotmielby orai iret ede een ugbceateh aca ia den mteque s eaten a etna a 9 Do MVE LEY OUT dc 9 Ma rc RET 9 3 1 1 Helical Layer Thickness Buildup cccccceccecceeseeceeceececeeceeceece
19. angles assigned to a bin is chosen by the user as the wind angle increment in the Tank Manager Dialog as shown in Figure 4 6 Wind angle bins are then generated from O to 90 degrees based on the wind angle increment For example 90 bins would be created for a wind angle increment of 1 degree All elements with wind angles falling within the range of a given wind angle bin is assigned a single material property based on the wind angle of the bin No materials are created for bins which have no elements associated with them The orthotropic materials for each wind angle bin are calculated as angle ply laminate 0 materials where the angle 0 is the bin wind angle The orthotropic material properties input by the user are for the composite lamina single ply with 1 fiber direction 2 transverse and 3 normal The plug in transforms these material properties to the global directions 1 meridional 2 hoop and 3 normal These transformed material properties along with a section definition are assigned to each wind angle bin and written to include files described in Section 4 6 1 Material properties other than orthotropic ELASTIC CONDUCTIVITY and EXPANSION are assigned directly to the wind angle bin material without being altered and are also written to the include file 4 4 Load and Boundary Assignments The load options consist of thermal loads an internal pressure load and boundary conditions The thermal load options simply allow a uniform ini
20. d layer type Figure 3 1 Winding Layout Table 3 1 1 Helical Layer Thickness Buildup The thickness specified in the winding layout table is the thickness at the cylinder tangent line As the layer traverses the dome to the polar boss the thickness of the helical layer gradually builds up as described by Equation 3 1 1 10 B fil COS Oa li er el py BP Ti ro ti thickness at the tangent line Ou wind angle at the tangent line 0 wind angle at radius ri radius at the dome cylinder tangent line ro radius at the helical turnaround point BW helical band width 0 0 r sin se n d l r Fil ro Equations 3 1 1 3 1 2 Helical Shear Ply Often a rubber shear ply is applied over the liner of the pressure vessel to accommodate the shear strain between the vessel and first filament wound layer The shear ply can be modeled by defining a helical layer with friction specifying its terminating inner radius and setting the band width to zero If the layer is assigned an isotropic material then the wind angle calculations are skipped and the layer is simply assigned the isotropic material properties Figure 3 1 2 Zero Bandwidth Shear Ply 3 1 3 Helical Layer with Friction A helical layer with friction HELICAL_FRIC requires the wind angle and turnaround radius be specified The wind angle distribution is determined from of Equation 2 1 with the value of n set to 1 0 This equation essentially
21. e strain along the fiber direction in the negative wind angle direction UVARM3 the strain transverse to the fiber direction in the positive wind angle direction UVARMA4 the strain transverse to the fiber direction in the negative wind angle direction UVARM5 the stress along the fiber direction in the positive wind angle direction UVARM6 the stress along the fiber direction in the negative wind angle direction UVARM 7 the stress transverse to the fiber direction in the positive wind angle direction UVARM8 and the stress transverse to the fiber direction in the negative wind angle direction UVARMO For Heat Transfer analyses UVARM2 and UVARM3 are filled with the heat flux along and fibers and transverse to the fibers For Coupled Temp Displacement analyses UVARM10 and UVARM11 are added as the heat flux along the fiber direction and transverse to the fiber direction An option is provided for allocating more memory for user output variables This is useful if the UVARM subroutine is to be expanded to include more user defined output variables The plug in then sets the USER OUTPUT VARIABLES keyword option in every material definition automatically A source file wcUvarmUltils py is provided to allow automatic merging of user defined UVARM coding with that created by the plug in Two functions are provided writeDeclarations and addExtra The first inserts declarations statements immediately 35 following the generic declaration sta
22. eceeceeceeceesuesuesuesuesueseeseesenseeeas 10 3 1 2 Hellcal Shear Pit a a IO 11 Se lsd FICHGAl Layer WA FICO lit ted 11 ADE A A E 12 A WAVE gi C 4 t 12 9 4 Vold CFreallODissesicsaiae e ott uua idi inet ditur sca ee aet ederet hesstcnetutan n ette dc d isde ches a 13 3 0 Layer Terminatoh ODLUOFIS ome dtt iniecto eee 14 3 0 Layer Love Contool secession eee 15 JO ode S cea a a 16 3 6 2 Layer Level Mesh Controls a ia 18 ono CAD DAT EID eerte vec c t 19 94r Dome Level Mesh Controls curia tol a E Ml a thet e A E 21 4 Wound Composite Tank Creation nica A as e A A A see o gR ORE 23 A C n 23 4 1 1 Axisymmetric Continuum GEOMETIY cece cc cece cece eee eeeeeseece eee eeseeeeeeseeseeeseeaeeeeeeeeeseeeaeeseenaes 24 41 2 SD Cont n rm GeonellV sen tds 24 Ao GD SMEM GEOMIC OY vos E m m c aaseancoass 26 4 1 4 Axisymmetric Shell Geometry cooccoccconconcccnconcncononcnnnncononcnnonnonnnnnnnnnnnanonnnnnnnnnnnrnnnnnanennnnnns 28 4 1 5 Continuum Shell Geometry ui iio o t ee eee Oe ese net t eben eet incepet bauen aes 28 AZ DOME ASSIM CERE 31 2 3 SECON ASSOMMER sii dE 31 42351 Material Properties as 32 4 4 Load and Boundary ASSIM Sa dc liada cecilia 33 A S Mes Crealo mS 34 OSO OF m C A A eee ee ee eee ee one 34 4261 ACIS TMCS TL 34 AO 2 UVA M
23. ed In such a case the wind angle between the two domes is linearly interpolated over the length of the cylinder If either of the domes contains doilies then the global layer numbers of the full tank will differ from that of the individual domes All warning and error messages written by the plug in refer to global layer numbers so a map between the local dome layers and the global tank layers is necessary Clicking the Layer Map button brings up a dialog providing the map as shown in Figure 4 1 2 In the example shown the second layer of each dome is a doily ll ayer Map Active Global Local Layer Dome Layer Humber Number woundcomp 1 wouncdcomp 2 woundcomp L woundcomp 2 woundcomp 1 woundcomp 2 woundcomp 1 woundcomp 2 woundcomp 1 woLuncdcomp 2 Dismiss Figure 4 1 2 Layer Map Dialog 4 1 1 Axisymmetric Continuum Geometry Choosing axisymmetric continuum elements will result in a model exactly the same as the combination of the two axisymmetric domes 4 1 2 3D Continuum Geometry If three dimensional continuum geometry is chosen a table appears in the Tank Manager Dialog as shown in Figure 4 1 2 1 below The domes chosen provide a two dimensional sketch which can be swept between 0 and 360 degrees to generate a three dimensional part The swept geometry can be broken into equally spaced segments by assigning a number to the Number of Segments entry Partitions are generated in the swept geometry to cut i
24. ent may be assigned a different number of elements as shown in Figure 4 1 3 2 Modeling Space CO Axisymmetric Continuum Axisymmetric Shell CO 3D Continuuum 3D Shell 30 Shell Controls Number of Elements 100 Bias ratio gt 1 1 Section Integration During Analysis Before Analysis 30 Sweep Geometry Sweep Angle 30 Number of Segments Eg Number of Elements 16 2 12 3 6 Figure 4 1 3 1 3D Shell Tank Creation Options 26 Teee TINT ATEO HN u IN II AN CCOO niii PDA Figure 4 1 3 2 Differing 3D Shell Segment Meshes The shell section definitions of the elements along are determined by examining the layouts of the assigned domes The shell element geometry shown in red in Figure 4 1 3 3 is determined from the inner surface of the domes The shell section properties are specified by calculating the normal at the centroid of each shell element then determining the stack lay up in the direction of the outward shell normal at the element cen troid The shell section is then offset by half the thickness of the lay up The thicknesses at the nodes are assigned via the NODAL THICKNESS option by determining the stack lay up thicknesses at the nodal locations Because of the axisymmetric geometry and wind angle orientation assumptions the shell section definitions are grouped together in the hoop direction to minimize the number of sections thus im
25. ents for the composite layers Wound Composite Vessel Mame MicTank Tank Domes Geometry Space Section Assignment Model Generation Analysis Type CO Static Heat Transfer G Coupled Temp Displacment C2 Dynamic Explicit Element Geometric Order Element Shape Quad Element Formulation Reduced Integration Element Types SBRT An node thermally coupled quadrilateral general thick shell biquadratic displacement bilinear temperature in the shell surface Figure 4 3 Tank Level Section Assignments 3D Shell 4 3 1 Material Properties The assignment of material properties to the tank begins by assigning section definitions based on the materials provided for each layer in the winding layout table The plug in then determines which layers have orthotropic materials assigned to them ELASTIC CONDUCTIVITY or EXPANSION The elements in the orthotropic layers are assigned transformed material definitions and section assignments which are written to an include file as described in Section 4 6 1 32 The calculation of orthotropic materials properties is performed by first creating wind angle bins for each orthotropic material That is to say all the elements assigned a given orthotropic material are grouped together based on wind angle and put into bins The local wind angle of each element is calculated from Equation 2 1 based on the centroidal coordinates of the element The range of wind
26. er as opposed to having only a single mesh seed constraint at the bottom of the dome This helps to ensure the number of elements through the thickness remains uniform throughout the layer 22 Figure 3 7 2 Geometry Mesh with and without Partitioning 4 Wound Composite Tank Creation 4 1 Overview The final creation of the composite overwrapped pressure vessel model is performed by choosing from the library of domes for the top and bottom domes of the tank and selecting the modeling space of the tank via the Wound Composite Manager dialog shown in Figure 4 1 1 The parts created when generating the domes are axisymmetric and act as a guide when generating tanks of the various available geometries However the tank geometry may be axisymmetric or three dimensional Wound Composite Vessel Mame MeTank Geometry Space Section Assignment Model Generation Wound Composite Domes Dome Bottom of Create Name Tank Wound E mem pum WES Woundcamp 1 Figure 4 1 1 Wound Composite Tank Manager Dialog 23 If a top and bottom dome are assigned to the tank they do not necessarily have to be identical They are required however to have matching layers at the interface between the two That is to say the layers at the interface must be of the same type must have the same thickness and for helical layers must have the same wind angle The wind angle may differ between the domes only if one or both domes have cylinders attach
27. es at a position along the tank axis as shown in Figure 3 3 The termination position is defined relative to the interface between the dome and the cylinder Thus if a cylinder is attached to the dome then a negative termination position would define a hoop terminating on the cylinder Conversely a positive termination position would define a hoop terminating on the dome A hoop layer is usually orthotropic like a doily with the primary material direction rotated from the meridional axis of the tank by the value of the wind angle 12 Figure 3 3 Hoop Layer in Blue 3 4 Void Creation When one layer overlaps the end of another layer a single void will be created as shown in the figure below The length of the void is equal to the thickness at the termination of the layer being overlapped times the void fraction of the layer being overlapped The void fraction is a layer level control parameter which may be modified to contract or expand the size of the void and is shown in Figure 3 4 1 The mesh of the void will always be constructed of triangle elements or in the case of 3D continuum geometry wedge elements The Wound Composite Dome dialog requires a resin or void material to be assigned to any wound composite dome This material will be applied to all voids in the dome Figure 3 4 1 Single Void If the outer radius of a doily and the inner
28. ficant controls over the characteristics and quality of the final mesh The layer level controls override the dome level mesh controls described in Section 3 7 18 Layer Data CAD Data Mesh Controls Layer Mesh Controls Number of elements through this laver 2 Element Formulation Hybrid Formulation Reduced Integration Incompatible Modes Mesh Seed Contraint Through Layer C allow the number of elements to increase or decrease gm i C Allow Ehe number of elements to increase only C3 Do not allow the number of elements to change Figure 3 6 2 1 Layer Level Mesh Controls Tab Input The number of elements through the thickness of a particular layer may be specified in this dialog Resulting mesh seeds are applied through the thickness of the layer at the base of the dome or in the case of an attached cylinder at the interface between the dome and cylinder If partitions are prescribed as discussed in Section 3 7 the mesh seeds are applied on the segment of the partition passing through the layer of interest The mesh seeds assigned through the thickness may be constrained to increase decrease or remain fixed through this dialog The element formulation may be assigned to the layer by selecting any combination of the HYBRID REDUCED Or INCOMPATIBLE MODES formulations 3 6 3 CAD DataFitting Tables of CAD data lines containing radius y position wind angle and thickness are often available as output from fi
29. g back into the winding layout table 3 1 Helical Layers The helical layer types HELICAL_FRIC HELICAL_NOFRIC of a wound composite are typically wound in such a manner as to produce an axisymmetric layup In other words for every helical band at theta there is a corresponding band at theta to cause the overall laminate to be a balanced angle ply theta laminate This assumption is implicit in an axisymmetric model Therefore the wound composite plug in requires only a single orientation angle to be given for each layer at the tangent line and the plug in will calculate the angle ply laminate material properties for each element within each helical layer Two types of helicals are available with and without friction The wind angle distribution of both types of helicals is described by Equation 2 1 Dome Mame wwoundcComp 1 Mote 4 part will be created with this name Wound Dome Geometry Dome Mesh Controls Dome Winding Layout Controls Geometry Layer Termination Void Material Cylinder a Geometry O Material Name Resin RITU n ET Mot on End Cap n Move to Transition Point Info g Winding i Layout i Winding Layout Band Width Factor Layer 2 Wind Inner Duter Hoop Type Material Thickness Angle Radius Radius Height HELICAL FRIC T1000 0 04 S 0 5 1 DOILY Tro 0 05 20 0 2 0 HOOP TA00 0 05 90 0 HELICAL MOFRIC T1000 0 04 40 0 HELICAL FRIC T1000 0 05 ri Itemis not applicable to assigne
30. hus the representation of the layers is not exact 5 2 Import of CAD Data To generate a model from CAD data select the Plug Ins gt WoundComposites gt Import CAD Data item under the plug in drop down menu Then select the Import CAD Data toggle and submit the dialog The resulting dialog that is brought up is shown below in Figure 5 2 The first step is the selection of the mandral file The Select button allows you to browse your machine to select the mandral file The mandral and ply files do not have to be in the working directory Once the mandral file is selected the plug in scans through the file and populates the dialog with the top and bottom boss diameters the maximum tank diameter found and the y pos that represents the center of the tank The top and bottom domes will be separated at this y pos This information is used as a quick check on the data 37 The next step is to select a single ply file Any of the ply files can be chosen The plug in examines the name of the file selected and based on the naming convention described above scans the directory for any more ply files Each ply file is scanned and the layout is filled as shown in Figure 5 2 1 1 CAD Import Layout Point by Point CAD Data Files TopiLefti Polar Boss Diameter BottormRighti Polar Bass Diameter 48 26 Tank Diameter eof r oob Top Battom Dome Y Pos Interface 0 0 Laminate File name ply C JABAQUS 6 7 2 abaqus plugins We Mote The ply
31. icantly This is because the sketch of the exterior of merged layers is broken into many distinct splines due to the disconti nuities An option has been added to force the exterior of merged layers to be drawn as a single spline This causes a discrepancy from the actual geometry however the improvement in the match between stack direc tion and isoparametric direction more than makes for the discrepancy Below is shown an extreme case of this phenomenon Additional mesh partitions can also be added to further ensure that the isoparametric ele ment direction closely matches that of the stack direction mandral normal 30 Separate Exterior Merged Exterior Splines splines Figure 4 1 5 4 Left Separate Exterior Splines Right Merged Exterior Splines 4 2 Dome Assignments The assignment of domes is performed by clicking the Assign Dome button The dialog shown in the Figure 4 2 shows how the top and bottom domes are assigned A single wound composite dome may be chosen as the top bottom or both domes of the tank Figure 4 2 Dome Assignment Dialog 4 3 Section Assignments The options available from the Section Assignment tab determine which element type or types will be assigned to the mesh Based on the options chosen the element type s are printed at the bottom of the tab area The groups of the options are arranged in a hierarchy of dependence At the top of the hierarchy is that of the geometric space defined under the Geomet
32. ius 24 13 i 17 Figure 3 6 1 4 CAD Data Band Width Settings Extended Turnaround Radius Last CAD point E i ZN ORS as p BandWidth BW Figure 3 6 1 5 Modification of Turnaround Radius due to Band Width Setting the end type to NONE_VERT will cause the last couple of CAD data points to be modified if necessary to ensure the end abuts the polar boss properly and is aligned vertically The radius of the polar boss is set during the import of the geometry and at present can not be modified The thickness at the end of the layer however may be modified based on the position of the band If the CAD data positions are measured at the inner most edge of the band then the thickness at the polar boss will be determined directly from the CAD data However if the CAD data positions are measured at the center of the band then the thickness will be extrapolated from the last CAD data point to a position one half of the width of the band away Setting the end type to CAD_DATA will instruct the plug in to use the points defined in the CAD data exactly up to a point which is one half of the width of the band away from the turnaround radius From this point to the turnaround point the layer thickness in linearly ramped down to zero 3 6 2 Layer Level Mesh Controls The layer level Mesh Controls tab as shown in Figure 3 6 2 1 allows individual layers to be assigned mesh controls that give the user signi
33. lament winding machines In order to generate a COPV model from this data helical layers with friction or hoop layers may be created during the import of CAD data Selecting the CAD Data tab from the layer level controls dialog shows the CAD data read during the import process Right clicking on the table provides a method for refilling the table by reading from a text file The text file must contain four columns of numbers separated by either a comma or a blank space Individual rows of the table may edited or removed altogether Layer Data CAD Data Mesh Controls Import From CAD Data CAD Angle degrees 119 6764745 0 0 12 632114 0 0404 Thickness Radius Pos se 119 6764 745 0 152936 1 632114 0 624524 119 6764 745 0 259808 1 632114 0024024 119 6764745 ogol 12 632114 0 624524 119 6764745 1 7 258527 12 632114 0 0404 19 Figure 3 6 3 1 Cad Data Import Tab The first and last entries of the CAD data define the bounds of the wind angle curve with friction The lower bound as shown in blue in Figure 3 6 3 2 is determined from the frictionless wind angle curve of Equation 2 1 for the wind angle specified from the CAD data at the tangent line The upper bound is based on the frictionless wind angle curve that would terminate at the turnaround radius specified from the CAD data The black line shows the default behavior which sets the curve exponent n of Equation 2 1 to 1 0 The green line shows what a curve might look like for
34. lder should be copied to a folder named home dirabaqus plugins in the user s home directory 9 References Papers 1 Peters S T Humphrey W D and Foral R F Filament Winding Composite Structure Fabrication a Edition 2 Gray D L and Moser D J Finite Element Analysis of a Composite Overwrapped Pressure Vessel American Institute of Aeronautics and Astronautics 3 Skinner Michael Trends advances and innovations in filament winding Reinforced Plastics February 2006 Abaqus References For additional information on the Abaqus capabilities referred to in this brief please see the following Abaqus Version 6 7 documentation references e Analysis User s Manual e Abaqus GUI Toolkit User s Manual e Abaqus User s Manual 45
35. lug in will flip the dome geometry if necessary The option of connecting the discrete points by straight lines or by cubic splines is provided Generally using splines will result in smoother shaped geometries Mote Apart will be created with this name Wound Dome Geometry Dome Mesh Controls Dome Dome Geometry Geometry Cylinder Geometry Winding User Defined Dome Geometry Layout 1 2 3 d 5 b T g y j j jl jm t M m 2D 14 9 603212565414 9 40974011206 B 75050614956 6 00406409492 T 60034254275 P 38452997739 622970503601 5 9654560701 7 4 40502040000 4 454260 76995 Y 9 0 3 25 2 5 10 0 12 0233208291 12 2814285601 13 4415245134 13 6468911056 14 5407 130732 14 6934009131 15 3335484046 15 438122081 15 8548436963 15 3185343814 Segment Type Between Points CO Straight 9 Spline 2 4 From Part Instance Dome Wound composite layers can be made to wrap over an existing part instance that has been meshed within Abaqus CAE The part instance must be meshed but may have been created from an imported orphan mesh native geometry or imported geometry The points of the underlying wound composite dome Figure 2 3 User Defined Dome Input Last Point First Helical First Point geometry are extracted from the nodal coordinates along the outer surface of the part instance In order to define the outer surface which may be overwrapped the user is required to generate a node set I
36. multiple merged layers is repre sented by one element through the layer thickness all along the length of the layer If the mesher puts more than one element through the thickness of any merged layer then more partitions need to be added to en force the requirement of one element through the thickness The section definition of each element along a merged layer includes a stack containing any merged layers comprising the element This stack is determined in the same way as that of 3D or axisymmetric shells ex cept instead of accounting for all of the elements of the tank only the layers merged within the specific global layer are considered The figures below show a model before and after the merging of layers 29 Figure 4 1 5 2 Three D Continuum Element Mesh Figure 4 1 5 3 Three D Continuum Shell Mesh with Merged Layers When determining the stack of an element the plug in searches through the layers along a vector passing through the centroid of the element The vector is calculated to be normal to the underlying tank geometry mandral geometry Since the stack direction of continuum shell elements must be along one of the ele ment s isoparametric directions the chosen isoparametric direction must coincide as closely as possible with the vector used to determine the stack For complex geometries which consist of many merged layers gen erating discontinuous layer geometries the isoparametric and stack directions can differ signif
37. n the case of a three dimensional model this node set should be in the x y plane with the axis of the tank in the global y direction The plug in then generates the dome geometry from all of the nodes between the first and last nodes The option of connecting the points using straight lines segments or splines is available Figure 2 4 Helical Layers on Part Instance 2 5 Cylinder Geometry A cylinder may be added to the top and or bottom domes on any of the dome geometries The wind angle of helical layers remains constant over the length of the cylinder If there are no hoops that terminate along the length of the cylinder then all of the elements in a layer along the cylinder will be assigned a single material property and orientation If a hoop terminates on the cylinder then separate orientations are assigned to each element of each layer on the cylinder If the liner geometry is defined from an existing part which contains a cylinder length then cylinder of the wound composite layers can be defined in one of two ways First the cylinder geometry may be included in the dome by selecting the start point to include the cylinder and the end point at the polar boss or turnaround radius Secondly the node set can be defined on only the dome with the cylinder being generated by the plug in by manually specifying a cylinder length 3 Winding Layout The dialog box of the WINDING LAYOUT tab is shown in Figure 3 1 Each layer is assigned a laye
38. ngle axisymmetric or three dimensional tank model then selecting the loads and boundary conditions to be applied to the tank Creating a wound composite dome begins by selecting the Plug Ins gt WoundComposites gt Manager menu item which then brings up the one of the two major dialogs of the Wound Composite Modeler the Wound Composite Manager dialog From this first dialog selecting the CREATE button from the TANK GEOMETRY tab brings up the second major dialog the Wound Composite Dome dialog From this dialog any axisymmetrically shaped dome with a cylinder attached can be generated A toggle is supplied to skip the time consuming step of generating a mesh thus reducing the time required for each iteration on the 3 geometry Once satisfactory dome geometry has been created then the toggle for mesh creation can be turned back on and iterations on the mesh can then be performed Creation of a dome results in the creation of a part within Abaqus CAE However this part is not instanced into the model This part serves as a guideline for the creation of a portion of the tank and may be one of a library of domes The final tank model is created by choosing a top dome and possibly a bottom dome from the library of domes then combining them to make the final tank model The domes to be used are selected from the Wound Composite Manager dialog Creation of the model is performed upon submission of the dialog The tank loads and boundary conditions
39. ollowing increment of wind angle 15 Subroutine UVARM creation Generate UVARM subroutine Number of Additional Uvars E Figure 4 6 Model Generation Inputs 4 6 1 Include Files Turning on the toggle for generating the material and section properties will transform the material properties which are defined along the fiber direction to material properties defined in the global axisymmetric coordinate system Since the orientation of the fibers is different at each element of a helical layer a separate material and section assignment would be required as described in Section 4 3 Creating this many material definitions and section assignments within Abaqus CAE would make editing them almost impossible and would slow down the CAE interface significantly Thus the properties are grouped into bins So the plug in assigns a single material and section definition to each layer from within Abaqus CAE then overwrites them by inserting two INCLUDE statements into the keyword editor One INCLUDE statement referencing 34 TankName_sections inc is inserted into the part block It contains all of the section definitions The second INCLUDE statement referencing TankName_materials inc is inserted into the model definition It contains the material definitions and material orientation definitions Figure 4 6 1 Wind Angle Bins of 0 5 Degrees When the job is run the batch pre processor will print a warning that numerous elements have
40. or may interact with the COPV part as desired Once any changes to the COPV part have been made then the material properties need to be recalculated The REGENERATE PROPERTIES button of the Wound Composite Tank Manager dialog brings up the dialog shown in Figure 4 7 Submission of this dialog will cause the material section and orientation properties to be recalculated and the include files will be updated accordingly MW Regenerate Externally made changes to mesh 36 Figure 4 7 Include File Regeneration Dialog 5 Model Creation from CAD Import The creation of a model can be performed automatically by importing CAD data which defines each layer on a point by point basis The underlying dome geometries are defined via a single mandral file The geometry of each layer is defined by a ply file for each layer The mandral file man is formatted as below with the first number defining the y position along the tank and the second number defining the inner tank diameter at that position Horizontal Position 1 Diameter 1 Horizontal Position 2 Diameter 2 The layer files are named with a special convention described below to allow the plug in to automatically read all the layers at once The ply files must all be located in the same directory Name plyn m ply Where Name arbitrary string same for all layers n ply number starting with 1 m arbitrary string often wind angle The ply data are written in the following format
41. proving performance in the solvers Nodal Thickness Figure 4 1 3 3 Laminated Shell Sections 2 4 1 4 Axisymmetric Shell Geometry Choosing axisymmetric shell geometry results in line geometry created at the inner surface of the axisym metric domes The procedure for determining the shell section definitions for axisymmetric shells follows the same procedure as that of the three dimensional shells The nodal thicknesses are also calculated in the same manner as the three dimensional shell elements 4 1 5 Continuum Shell Geometry The model size of three dimensional continuum models can quickly overwhelm the capacities of most hard ware systems In order to reduce the size of three dimensional continuum models an option is provided to merge the properties of selected layers into a single laminated continuum shell element This allows the size of the model to be significantly reduced while retaining most of the accuracy of the full model The process of creating a merged layer continuum shell model follows the same process as that of the stan dard three dimension continuum model except an additional step of selecting the layers to be merged is ini tiated by selecting the MERGE LAYERS button This brings up the dialog shown below Layers may be high lighted then by clicking on the MERGE SELECTED ROWS they are assigned the same global layer number shown in the far right column of the dialog The rows selected during this process mus
42. r type material thickness and wind angle The inner and outer radius hoop height and band width factor are applicable to specific layer types A row of buttons is listed below to assist in table manipulation The Edit button brings up another dialog which allows detailed controls to be applied to each layer as will be discussed later The Add button creates a new layer which is a copy the highlighted layer including all of its layer controls information The Move Up and Move Down buttons simply move the entire layer along with its control information up or down Multiple layers can be moved up and down simultaneously The From File button allows the layout to be read from a file The text file to be read may have any number of rows and columns with the columns separated by spaces or commas The first column of the text file corresponding to the Active column of the table must use either True or False A warning will be printed if the material specified in the third column is not active in the model Columns 10 and beyond of the text file can be used to specify the controls of each layer To determine the type of format for these columns select a dome and click on the Query button from the Tank Manager dialog This not only prints a summary of the wound composite dome attributes to the command line interface but also writes a text file named wound composite dome name txt which contains the winding layout of the dome in the format required for readin
43. radius of another layer are close enough to each other then a layer which overlaps the two may create what is referred to as a double void as shown in Figure 3 4 2 13 Figure 3 4 2 Double Void Its possible to wrap a layer over more than two underlying layers which terminate near one another but the geometry creation in such a case is likely to fail The end type of a layer can be assigned as NO_VOID in which case no void is created when one layer over wraps another The shape of the end cap is created such that the slopes at the beginning and end of the end cap generate no discontinuities This ensures that the layers which are placed over top will in turn not contain any discontinuities Figure 3 4 3 No Void End Type 3 5 Layer Termination Options When on layer terminates near the end of another it becomes very difficult to determine the geometry of additional layers that may overlap them For this reason the default behavior of the plug in is to disallow one layer from terminating on the end cap of another The end cap definitions are discussed in detail in Section 3 6 1 An option is however provided to override this default behavior The Transition Point option will automatically move the turnaround radius of any layer terminating on the end cap of an underlying layer to the radius of the transition point of the underlying layer s end cap The transition point is simply the beginning point of the end cap
44. rt Merge Layers SCAR d d d d d d d d Select all Deselect All Skip Material Calculations Create Input Files 2 Run Full Analyses Include Uvarm Subroutine View Archived Results Figure 7 1 QA Test Manager Dialog 8 Installation of Plug in The Wound Composites Modeler for Abaqus installation disc contains a single folder named WoundCompo sites which contains all the files necessary to run the plug in This entire folder and all its subfolders should be installed under an abaqus plugins folder as described below and should only be run in Version 6 7 of Abaqus When you start Abaqus CAE it searches for plug in files in the following directories and all their subdirecto ries e abaqus _dincaelabaqus plugins where abaqus dir is the Abaqus parent directory e home dinabaqus plugins where home dir is your home directory e current _dinabaqus plugins where current dir is the current directory 44 Abaqus CAE will import any files in these directories that match the naming convention plugin py The abaqus dir directory for Windows is usually C Abaqus 6 7 1 for Abaqus Version 6 7 1 Thus if it is preferred that any user in question who has access to the Abaqus installation be allowed access to the plug in then the WoundComposites folder should be copied to the abagus_dir cae abaqus_plugins folder If the plug in should be made available only on a user by user basis then the WoundComposites fo
45. ry Space tab All options on the Section Assignment tab are dependent on the options chosen above them 31 For example Figure 4 3 shows the section assignments available for three dimensional shell elements The Dynamic Temp Displacement option under Analysis Type is stippled since Abaqus Explicit does not provide for the use of three dimensional shells with this procedure Both Linear and Quadratic element orders are available for Coupled Temp Displacement analyses are available so both buttons can be selected Since the Quadratic button was selected for the element order only the Quad element shape is un stippled corresponding to the S8RT element Thus only quad shaped elements are available as second order three dimensional shell elements in a Coupled Temp Displacement analysis Since there are not hybrid or incompatible Coupled Temp Displacement shell elements that option is stippled With the exception of element order section properties follow the same controls scheme as the mesh controls The element formulation can be assigned globally to all of the layers Then individual layers may be assigned their own element formulation The element order is required to be the same throughout otherwise TIE constraints would be required between regions of first and second order elements This layer by layer control of element type allows the mixture of hybrid elements for rubber shear ply materials with standard or reduced formulation continuum elem
46. s Generates geometry and mesh only e Create Include Files Generates run ready model but does not submit the job to solver e Run Full Analysis Generates and runs model The displacements in the y direction at the ends of tank are extracted and compared to archived results An Abaqus CAE model named QaTestModel is created and saved of the last test chosen Thus if a particular feature is of interest you can scan through the test descriptions and run the test that best describes the feature of interest The resulting model QaTestModel will be created and readily available for editing and testing An option is provided to view archived test results This is useful when comparing baseline tests of the same model but different element types For example the tests in groups 4 5 6 and 7 are for the most part the same tests but using axisymmetric continuum geometry 3D continuum geometry axisymmetric shell geometry and 3D shell geometry respectively Selecting for example 4 1 5 1 6 1 and 7 1 then clicking the VIEW ARCHIVED RESULTS button will provide a comparison of results for the different element types 43 MM Wound Composite QA Test Manager 6 7 3 Choose Qa Tests to Run b ad Underlying Geometry Tests Winding Geometry Tests Section Mesh Misc Tests Analysis Type Tests E Axisvmmetric Continuum maeometrs F 3b Continuum Geometry Axisvmmetric Shell Geometry 3D Shell Geometry Full Model Impo
47. t be sequential i e row 4 can not be merged with row 2 unless row 3 is also merged Merged layers may consist of a single row Special care must be taken when merging models with doilies The exterior of merged layers must result in a single continuous group of points For example an invalid merge definition would result if one doily belong ing to the top dome and another to the bottom dome were selected but no layer joining the two was se lected The result would be the exterior of the merged layer consisting of two unique sets of points 28 MM Choose Layers to Merge Mesh Controls Mumber of Longitudinal Elements EX Number of Sweep Elements 4 Approximate Mesh Size Geometry Controls Merge exterior splines Global Layers Active Global Layer Assigned Layer Type Dome Number 1 HELICAL FRIC Bath DOILY Top DOILY Bottom HOOP Both HELICAL NOFRIC Both HELICAL FRIC Both HELICAL NOFRIC Both HELICAL_FRIC Both HELICAL_NOFRIC Bath HELICAL FRIC Both Merged Layer Mumber wo c Jj c Cn E Ww Ph RA Lom Lm Lm LER LE e a L Merge Selected Rows Unmerge Selected Rows Figure 4 1 5 1 Merge Layer Dialog Once the layers to be merged are selected submitting the dialog simply sets the layers to be merged Not until the tank manager dialog is submitted does the proper geometry get created The resulting geometry is a three dimensional continuum shell model in which each layer consisting of
48. t into equally spaced segments Each segment may be assigned a different number of elements as shown 24 Wound Composite Vessel Mame E Tank Dames Section Assignment Model Generation Modeling Space O Axisymmetric Continuum CO Axisvmmetric Shell 3D Cantinuuum CO 3D Shell 3D Sweep Geometry Sweep Angle degrees Number of Segments Number of Elements A 22 Merge Layers Choose Layers Figure 4 1 2 1 Wound Composite Manager Dialog Figure 4 1 2 2 Three Dimensional Continuum Mesh 4 1 3 3D Shell Geometry Selecting the 3D Shell geometry button will cause the additional options to be activated as shown in Figure 4 1 3 1 The number of elements specified is the number of elements along each individual dome including the cylinder length attached to the dome A biasing factor is applied to bias the elements toward the polar boss The larger the biasing number the more the elements are concentrated toward the polar boss The Section Integration options allows the laminated shell section to be integrated either at every iteration throughout the analysis or once at the beginning of the analysis Integration only once is intended for cases in which the geometry and material properties of cross section of the elements do not change significantly during the analysis Three dimensional shell geometry like the three dimensional continuum geometry can be swept between O and 360 degrees Each segm
49. tements of the UVARM subroutine described in the Abaqus User s Manual The second inserts coding immediately following the plug in s coding for filling its default UVARM variables The uvarm argument passed into both routines is the file object to be written to The nextUvarm argument is the first available UVARM an integer for user definition This number is typically is 4 for heat transfer 8 for coupled temp displacement and 6 for all other procedures The UVARM subroutine is not available in Abaqus Explicit so the UVARM toggle is stippled for the procedures related to Abaqus Explicit def writeDeclarations uvarm uvarm write C User Defined Declaration Statements n uvarm write REAL pin def writeExtra uvarm nextUvarm uvarm write C User Defined Uvarm Coding WM uvarm write CALL GETVRM PE ARRAY JARRAY FLGRAY JRCD JMAC n uvarm write 8 JMATYP MATLAYO LACCFLA n Figure 4 6 2 User Defined Modifications to UVARM Subroutine 4 7 Externally Made Changes to Model Submission of the Wound Composite Tank Manager dialog generates a complete run ready model of a COPV However if changes need to be made to the part representing the COPV then the following guidelines should be followed for the COPV part e Nochanges to geometry should be made e Mesh partitions can be added e Mesh seed changes and remeshing is permitted e Material changes are permitted Changes to non COPV parts are permitted and they may be tied
50. tial curing temperature distribution to be applied in the model definition and a final uniform room temperature to be applied during any subsequent step of the analysis In analyses where temperature is a degree of freedom the curing temperature is applied as an initial field quantity and the room temperature load is applied as a boundary condition In analyses where temperature is not a degree of freedom both temperature loads are applied as field quantities An internal pressure load is available by entering a value for MEOP maximum expected operating pressure shown in Figure 4 4 The step in which the pressure load is to be applied is also required If the dome geometry was defined from an existing part then the MEOP pressure load will be ignored since the surface that the load would be applied is not known The MEOP load would therefore need to be applied from within the load module of Abaqus CAE Finally an option to apply boundary conditions on the symmetry planes is made available For a single dome tank checking the boundary condition toggle will result in the creation of a boundary condition in which the entire symmetry edge is constrained in the y direction Three dimensional models swept 180 degrees or less will have boundary conditions applied to the two planes The boundary conditions will be transformed to the proper cylindrical system For tanks with a top and bottom dome the boundary condition at the interface is only applied
51. tric model of the entire tank is generated The CAD data is stored for each layer and may be modified If using the exact geometry is not practical due to discontinuities in the data a least squares fit of the CAD data may be chosen for any given layer and the tank geometry may be regenerated 5 2 4 Tank Geometry Validation A comparison between the sketch of the raw CAD data and the sketch used to create the tank can be generated in order to verify that the tank was generated properly To do this edit the Wc Exterior sketch then insert the WoundCompName_LayerPartitions sketch into the existing sketch where WoundCompName is the name of the dome used for the top or bottom of the tank If both domes are being used then the top and bottom dome sketches will need to be inserted Finally insert the CAD_PlySketch into the existing sketch and you will see a sketch similar to the one below Keep in mind that the lines being sketched from the CAD data represent the bottom of the layer while the lines being sketched from the tank model represent the top of the layer In the sketch below you can also see where the plug in filled in the unknown geometry of the tapering ends 39 Figure 5 2 4 Raw CAD Data vs Tank Sketch 5 2 5 Diagnosing Problems with CAD Import A number of tools have been made available to assist in the diagnosing of problems with CAD data import As already described and CAD data sketch can be compared with the sketch generated by the
Download Pdf Manuals
Related Search