Altair OptiStruct 2022 Release Notes

Highlights

• Pressure Penetration
• Rate Dependent Plasticity
• Solder Fatigue with Creep Material
• New Thermal Convection Bulk Data Entry and Subcase Information Entry, CONVG
• Axisymmetry Pptimization

New Features

Stiffness, Strength and Stability
Pressure Penetration
The pressure penetration feature defines pressure loading which can simulate fluid penetrating through the surfaces on a contact interface. The PRSPENE Bulk Data Entry can be defined as a follower load in Large Displacement Nonlinear Analysis.
Rate Dependent Plasticity
Rate Dependent plasticity is supported for Implicit Nonlinear Analysis. Strain-rate dependent stress-strain data should be defined with the TABLEMD Bulk Data Entry. Rate dependent plasticity input is also temperature dependent with TABLEMD. The type of strain defined in TABLEMD is plastic strain and the type of strain rate is also plastic. Isotropic, kinematic, and mixed hardening are supported for rate dependent plasticity. Rate dependent plasticity has already been supported for explicit analysis prior to this release.
Test data input for Creep (MATVP)
MATVP material supports test data as input wherein the TID field for MATVP can refer to the TABLES1 Bulk Data Entry containing creep strains versus time.
Constitutive Reference for JOINTG
The constitutive reference definition allows the user to specify the reference length and angle where the force and moments are zero. For example, the length of JOINTG in the input file could be different from the reference length defined by constitutive reference. Constitutive reference is defined in the PJOINTG Bulk Data Entry. Constitutive reference is available via PROPERTY=CREF for PJOINTG Bulk Data Entry. Constitutive reference is available for both implicit and explicit analysis.
Time Dependent MOTNJG for JOINTG
Motion for JOINTG with MOTNJG can be time dependent. MOTNJG Bulk Data Entry now has a new field, TID, which references the table data for the time versus motion scale factor input. The scale factors are multiplied with the VALUE field to determine the time-dependent motion on the joint degrees of freedom. Additionally, the TSTIME field is also available to switch between total and subcase time to look up the table data.
Explicit Dynamic Analysis
Rotation option for TIE
Rotational dofs can be included in TIE constraints by setting the ROTA=DRILL option in the TIE and CONTACT Bulk Data entries.
Fully-integrated first order Hexa elements with incompatible bubble function
Fully-integrated first order Hexa elements with incompatible bubble function is available through the ISOP option (=FULL) on PSOLID.
Cowper-Symonds rate dependent plasticity
Cowper-Symonds rate dependent plasticity material model is now available for explicit analysis. The continuation line with CSYMONDS in MATS1 Bulk Data Entry will activate the model, followed by the required material constants. This model requires the reference rate stress-strain curve, either by using a table (TID) or by using the hardening modulus H in the MATS1 card.
Adaptive Dynamic relaxation can be used for explicit analysis. This option can be activated by the Subcase Information Entry, DYREL=YES/NO (NO as default).
Heat Transfer Analysis
New Free Convection Bulk Data Entry, CONVG
The input definition of free convection requires multiple Bulk Data entries such as CHBDYE, CONV, PCONV, SPC and the corresponding GRID entries. The new free convection definition only requires Bulk Data Entry CONVG which automatically generates the free convection entries. PARAM,CONVG, YES can be used to output the internally generated entries coming from CONVG Bulk Data Entry.
In addition, the Subcase Information Entry CONVG is added which references the CONVG or CNVGADD Bulk Data entries. Subcase selector CONVG allows the subcase dependent convection (different CONVG for different subcase or subcase without any convection).
Even when there is non-zero physical distance between the main and secondary surface, the contact is assumed to be closed for thermal TIE/FREEZE contact.
TSTIME in TLOAD1 and TLOAD2 is now supported also for linear and nonlinear transient heat transfer analysis
In case the IC Subcase Information Entry is used to create the continuation of subcases, the time definition in time dependent loading (TLOAD1/2) can be defined as either subcase time or total time with the TSTIME option in TLOAD1/2.
Noise and Vibration
Automatic adjustment of Normal direction of panels for ERP
The normal direction of a panel will automatically be flipped in case it is not consistent across the panel used for ERP. This is required for ERP output.
Modal effective mass output for component, property or element SET
COMP, PROP, and SET options are added in the MEFFMASS I/O Options entry for component, property, and element SET based Modal Effective mass output.
Material-based Rayleigh Damping
Rayleigh damping can be specified on the material level. Supported materials with Rayleigh damping are MAT1, MAT2, MAT8, MAT9, MAT9OR. The ALPHA and BETA fields on the RAYL continuation line can be used to define material-based Rayleigh damping.
Reduced damping matrix for global damping in CMSMETH
Global damping is now used to generate the reduced damping matrix during CMS analysis. Supported global damping for reduction with CMS is PARAM,G, PARAM,GFL, PARAM,ALPHA1, and PARAM,ALPHA2. PARAM,CMSGDMP, YES is required to activate reduction of global damping in CMS analysis.
Fatigue
Restart the calculation based on Linear Static Analysis results
The IMPORT Subcase Information Entry and ASSIGN,H3DRES entry can import static analysis results from .h3d file and start fatigue calculation. The entries can also be used in a local model using submodeling, which also contains the SPC data for interface mapping. This local model setup can include a fatigue subcase for damage/life calculations. For more details, see the IMPORT documentation.
Solder fatigue with creep material
Solder Fatigue based on the creep deformation of solder joints is now available. The fatigue evaluation of solder joints are calculated either using creep strain or creep strain energy. Multiple methods of solder fatigue with creep material are supported, and can be activated by selecting from SYEDEPS, SYEDW, or DARV options for the METHOD field on the SOLDER continuation line in the FATPARM Bulk Data Entry. Additional material data can be defined on the SOLDER continuation line of the MATFAT Bulk Data Entry. See the Solder Fatigue documentation for more information.
Optimization
Augmented Lagrangian Method (ALM) for topology with stress constraints
An alternate way to handle the stress constraints in topology optimization can be activated by DOPTPRM,ALMTOSTR, 1. For certain types of topology optimization, ALM may produce more discrete topology results than the default method of stress constraints for topology. ALM is supported for level set topology method as well. If DOPTPRM,ALMTOSTR, 1 is not specified, then the default stress-norm method is used to handle stress constraints.
Optimization support for axisymmetry elements
Optimization is now supported for axisymmetry elements for linear static analysis. Supported design variables are shape (including free-shape) and material sizing (parameter) optimization with DVMREL. Supported responses for linear static analysis are compliance, displacement and stress. For normal modes analysis, frequency can be used as the optimization response.
General
New Global-Local/Submodel
This new method is a two steps approach. First, the global analysis results (displacement/rotation) should be saved in the H3D file. This H3D file can be imported in the local model with I/O Option Entry IMPORT. SPC/SPCD with a value field of string M will define which grids in the local analysis that the displacement/rotation from global analysis should be mapped to.
This submodel approach is supported for linear and nonlinear static analysis.
New OPTI format
The OPTI output format has been enhanced with labels for improved readability.
• The new format can be activated using PARAM,OPTI, NEW and can be toggled off using PARAM,OPTI, OLD, which is the default behavior.
• The older/existing OPTI format is still available for the results/analysis types not mentioned in the PARAM,OPTI Bulk Data Entry.
• For more information on supported results and anaylsis types, refer to the PARAM,OPTI Bulk Data Entry.
FAILURE output for Transient Analysis
The FAILURE output request is now available for linear and nonlinear transient analysis. Failure criteria are based on von mises, tresca, major principal or minor principal stress.
DMIG energy in punch file
Strain energy of DMIG can be requested with ESE(DMIG,PUNCH) for static and normal mode analysis. Kinetic energy for DMIG is also available for normal mode analysis with EKE(DMIG,PUNCH).
Maintain the original user IDs in H3D for parts and instances
Grids/element IDs were offset by large numbers for each part prior to this release. Now the original grid/element IDs are maintained in the H3D file that are associated with different entities pool.
MAXT for Buckling Analysis
MAXT eigenvector normalization option is now supported for bucking analysis. Eigenvectors are normalized to the unit value of the largest translational component.
New option for CFAST Bulk Data Entry
SWLDPRM,ASCHAUX, YES/NO has now been added.
SWLDPRM,ASCHAUX, NO (Default): The search of auxiliary points will be limited to the shells with the same PSHELL property. If the user specified GSMOVE and NREDIA have finished and the shell for the auxiliary point still cannot be found, the limit of the same PSHELL property will be dropped and the search will expand into different PSHELL properties for a further attempt.
SWLDPRM,ASCHAUX, YES: The search of auxiliary points will not be limited to the shells with the same PSHELL property for every attempt within the specified GSMOVE and NREDIA. The search attempts start from the shells with same PSHELL property and expanded into shells with different PSHELL properties until the search is successful.
Option to adjust precision for MATRIX output
OUTPUT,MATRIX has a new option added which is used to control the precision and format for matrix output. The format is defined using the Fortran syntax, which provides the number of entries per line, followed by the precision.
The .res file is not output by default
The .res file is no longer the default output file as of this release. The OUTPUT,HM or FORMAT,HM entries can be explicitly defined to turn on the .res output.
New job launch option for MultiScale Designer interface
In addition to the existing option (MDSDIR input file and configuration file) to specify the location of MultiScale Designer installation, the solver script option, -mdsdir and the environment variable, OS_MDSDIR are newly introduced. Newly added options should point to the OptiStruct plugin location.
-mdsdir C:\Program Files\Altair\2022.0\hwsolvers\MultiscaleDesigner\win64\plugins\optistruct
The order of priority with different options are:
• MDSDIR from the input file
• MDSDIR from the configuration file
• -mdsdir script option
• Environment variable
• Default installation based on ALTAIR_HOME
HDF5
Nodal coordinates in basic/local coordinate system can now be printed to an additional column in the /INPUT/NODE/GRID group of the .H5 file. This can be activated using PARAM,XB, YES and can be toggled off using PARAM,XB, NO, which is the default behavior.
The CFAST model information is now available in the /INPUT group of the .h5 file, and can be used for viewing results in HyperView.
MPI
• The Intel MPI library packaged in the installation has been upgraded to version 2021.2.
• Open MPI library support is now included as an additional option for MPI-based runs. It can be activated using the “-mpi o” script run option when using the Altair Compute Console (ACC). The Open MPI libraries are included in the installation and will be used (instead of the default Intel MPI) when the “-mpi o” option is specified for the run.

Resolved Issues

• The required memory has been reduced for a model with GROUNDCHECK.
• For explicit jobs, the off-diagonal term of inertia tensor in CONM2 is now supported.
• Error occurring for collinear RBE3, even with PARAM,RBE3COL specified.
• Error 7102 occurring with aeroelasticity TRIM solution even if the condition is satisfied (the number of AESTAT, AESURF, and so on).
• .rbody.fem file generated from the model with RBODY now has the correct format.
• Unnecessary AUTOSPC ocurring for the model with two RBODY tied with TIE contact.
• Stress and element force for beam with temperature loading, when there is an offset between neutral axis and shear center.
• With SURF option in stress output request, the stress for shells was not available in the previous release. Now the stress results for shells are available in the results file with the SURF option. For explicit analysis, the combination of multiple TICA/TIC was not working properly and is now fixed.
• Modal frequency response with DDM producing incorrect results with frequency dependent material/property.
• The request of larger than the necessary disk space for the AVL excite CMS reduction job.
• Local coordinate systems assigned on grids that are used for RBE2 now correctly take into account RBE2 definition in large displacement nonlinear analysis.
• Programming error for collinear RBE3.
• Damping energy is now correct with Rayleigh damping.
• The model with PFPATH that encountered an error when material damping is not defined in elements in control volume.
• The incorrect H3D file that output for normal mode analysis with GPFORCE(FBD).
• Mass output with OUTPUT,MATRIX was not correct when the couped mass was requested with PARAM,COUPMASS. This could cause the optimization which was running correctly in older version to not run properly in version 2021.2.
• The licwait license related option now works properly.
• Nonlinear analysis restart job with RESTARTR in MPI run no longer fails.
• Contact Traction results for FASTCONT are accurate.
• Model with MODCHG and RBE2 no longer crashes.