Altair OptiStruct 2022.2 Release Notes


  • Damage/Failure for Explicit Dynamic Analysis
  • 3D Rotor modeling for rotor dynamics
  • Subsystem-based H3D output
  • SECTION force output for Frequency Response Analysis
  • New OPTI format as default

New Features

Accessing Demo Model Files
You can now click a link, within an Example and Verification Problem, to download the required model file(s).
Important: This download option is only available if you (or any user) are connected to the internet. Users attempting to download a model file will be prompted with further directions on how to access the model file online. A zipped package of the model files can be downloaded from the Altair One Marketplace and extracted to a local machine or directory on your company’s local server.
Stiffness, Strength and Stability
Switch CGAGP base node-to-surface Contact to alternate node-to-surface formulation
CONTPRM,N2SFORM,NOCGAPG is now available to switch from CGAPG-base node-to-surface contact to alternate node-to-surface formulation.
Cohesive elements referencing MAT1 (Continuum)
The MID field on the PCOHE Bulk Data Entry can now reference MAT1 material (in addition to the previously supported MCOHE/MCOHED Bulk Data Entries).
Cohesive elements with traction only
Cohesive elements with only traction can be defined by leaving the DMGINIID and DMGEVOID fields blank on the MCOHED Bulk Data Entry. In this case, cohesive material behavior is linear elastic in nature. This is supported only for cohesive elements.
Temperature-dependent viscoelasticity
Temperature-dependent viscoelasticity is now supported via the MATTVE Bulk Data Entry. The Williams-Landel-Ferry (WLF) model and the Arrhenius (ARRHENIU) viscoelastic material models are currently supported. It is supported for Nonlinear Static Analysis and Nonlinear Transient Analysis with both Small and Large Displacement Analysis. It is supported for CHEXA, CTETRA, CPENTA, and CPYRA elements.
Unlimited number of terms for Prony series
Unlimited Prony series is now supported on the MATVE Bulk Data Entry via a new material model type Model=UPRN. If the number of terms of the Prony series is greater than five, then the unlimited Prony series via UPRN can be used.
Circumferential and spherical smoothing option for contact
The SMTYPE field on the SMOOTH continuation line on the CONTACT Bulk Data Entry can be set to CIRCUM for circumferential smoothing and SPHERIC for spherical smoothing. If this field is left blank, then, by default, the smoothing is done using a Bezier surface.
Material-based Rayleigh damping support for Nonlinear Transient Analysis
Material-based Rayleigh damping is supported for Nonlinear Transient Analysis via the RAYL continuation line on MAT1, MAT2, MAT8, MAT9, MAT9OR, and MCOHED materials.
STATUB(PRETENS) can point to the subcase which does not have PRETENS but STATSUB(PRETENS)
STATSUB(PRETENS) can now point to a subcase which does not have PRETENSION but contains another STATSUB(PRETENS).
CFAST, CWELD, CSEAM support for Nonlinear Transient Analysis
CFAST, CWELD, and CSEAM elements are now supported for Nonlinear Transient Analysis.
Consider thickness of shells even if the node set is used instead of surface set
If the secondary side in CONTACT is defined as a GRID SET referring to shell elements, then now the shell thickness is considered for both search distance and GPAD=AUTO.
Augmented Lagrangian Multiplier (ALM) method
A new method for contact stiffness control is now available called the Augmented Lagrangian Multiplier (ALM) method. The ALM method is applicable to Nonlinear Static and Nonlinear Transient Analysis and can be activated via CONTPRM,ALM,YES or the ALM continuation line on the PCONT Bulk Data Entry. Additional control is available via CONTPRM,ALMPTOL or the PTOL field on the PCONT Bulk Data Entry. The penalty stiffness is controlled via CONTPRM,ALMSFKN. The ALM method may be able to achieve an accurate result for contact interfaces with a relatively soft penalty stiffness. In some cases, there may be an increased number of iterations.
DAMP option for PJOINTG in Linear Transient Analysis
The DAMP option on PJOINTG is now supported for Linear Transient Analysis.
Explicit Dynamic Analysis
Damage criteria
Damage criteria for Explicit Analysis can be defined on the MATF Bulk Data Entry. The available criteria for damage are BIQUAD, TSTRN, TAB and INIEVO.
The BIQUAD criterion is a stress triaxiality based failure criterion mostly used for ductile metals. Its double quadratic curve shape describes the evolution of plastic strain at failure with respect to stress triaxiality.
The TSTRN failure criterion is a strain-based damage model which considers a linear evolution of the damage variable between two strain starting and ending values, in tensile loading conditions only.
The TAB failure criterion is a plastic strain based tabulated criterion. The table TABLEMD describes the evolution of plastic strain at failure with respect to stress triaxiality and, optionally for solids, with lode parameter.
The INIEVO failure criterion is specific and has the ability to define a failure approach based on the use of a DMGINI Bulk Data Entry and, optionally, a DMGEVO Bulk Data Entry. In the DMGINI Bulk Data Entry, only the DUCTILE criterion is available. In the DMGEVO Bulk Data Entry, only DISP and ENERGY evolution are available.
Time history output (THIST) in .hdf5 format
THIST Bulk Data and Subcase Information Entry are added for time history output. THIST is currently only supported for Explicit Dynamic Analysis. If the THIST Subcase Information Entry is defined in the subcase, the global energy (internal energy, kinetic energy, contact energy, hourglass energy, plastic dissipation, external work) is always available in time history output in the _TH.h5 file. Specifically, various outputs can be requested for entities such as GRID, SHELL, SOLID, and CONTACT's. The list of corresponding outputs that can be requested for each entity is available in the THIST Bulk Data Entry documentation.
Monitor volume (MONVOL)
MONVOL Bulk Data Entry is now supported to define a one-chamber gas filled structure with hybrid input of inflated gas. Atmospheric pressure can be defined via the PATM field, and ambient temperature can be defined via the TATM field.
Model change (MODCHG) for contact
Model change (MODCHG) is now supported for Explicit Dynamic Analysis.
Rayleigh damping
Both global and material-based Rayleigh damping are supported for Explicit Analysis. Material-based Rayleigh damping is supported via the RAYL continuation line on MAT1, MAT2, and MAT8 materials.
Noise and Vibration
Pressure results output in dB and dB(A) scales
PARAM,PREFDB is used to specify the reference pressure and activate the output of pressure results from fluid-structure interaction in decibels (dB) and A-weighted decibels (dB(A)) scales in the .h3d and PUNCH files.
PEAKOUT scaling option for structural response
For structural response, scaling options such as DBA, DB, are now applicable.
Rotor Dynamics
Multiple UNBALNC with same ids
Multiple UNBALNC Bulk Data Entries can now have the same identification numbers.
3D elements-based rotor modeling
Rotors can now also be modeled in 3D via the ROTOR Bulk Data Entry. Currently supported elements for the ROTOR Bulk Data Entry:
  • 0D elements: CONM1, CONM2
  • 1D elements: CBEAM, CBAR
Symmetry constraints for 1D topology
Pattern grouping for topology is now additionally supported for PBAR, PBARL, PBEAM, PBEAML, and PROD properties.
New OPTI format as default
The new OPTI format with enhanced labels for improved readability is now the default. The older OPTI format can still be activated using PARAM, OPTI, NO.
Multiple output request for the same format
If multiple output requests are specified, then, by default, the last instance takes precedence. Now, SYSSETTING(MULTIPLEOUTPUT=YES) is available, which when specified, will allow requesting the same output request in multiple formats. This is currently supported for STRESS and STRAIN output requests. For more information, refer to MULTIPLEOUTPUT in the SYSSETTING I/O Option Entry in the Reference Guide.
Partial DoF's allowed for EIGVSAVE in Frequency Response Analysis with AMSES
The ability to save partial DoF's via EIGVSAVE is now available in Frequency response Analysis using AMSES. For more information, refer to the EIGVSAVE and EIGVRETRIEVE Subcase Information Entries in the Reference Guide.
SECTION force output for Frequency Response Analysis
The SECTION force output is now supported for Frequency Response Analysis. For Linear Static Analysis, SECTION forces and moments are available automatically if a SECTION is created. For Linear Transient and Linear Frequency Response Analysis, SECTION forces and moments are available only if a SECTION Bulk Data Entry is created and the RESULTANT I/O Option Entry is used.
Subsystem-based H3D file output
Subsystem-based H3D file output is now available when results are required for a specific part of the model in a separate H3D file. It is activated by either of the following options:
  • SUBSYS keyword on the 5th field on the SET Bulk Data Entry and an element SET of TYPE=ELEM which creates a subsystem.
  • TYPE=SUBSYS with SUBTYPE=LIST on the SET Bulk Data Entry which creates a SET of subsystems.
The corresponding output request should also contain a SUBSYS=# command where # is the subsystem ID. The output is currently available in H3D format only (in regular H3D file only). The results for each subsystem is available in a filename#.h3d file where # is the subsystem ID.
Corner option for FAILURE output
The CORNER option is now added on the FAILURE I/O Option Entry. If the CORNER option is specified, then corner stress values are used to calculate the FAILURE output. For more information, refer to the FAILURE Bulk Data Entry in the Reference Guide.
NSM=ALL option for Non-Structural Mass
The NSM=ALL option is now available which can be specified either above the first subcase or inside individual subcases. It will use all NSM Bulk Data Entries in the model (NSM, NSML, NSM1, and NSML1). If NSM=ALL is used, NSMADD will be ignored.
GROUNDCHECK includes the check for DMIG superelement
GROUNDCHECK for DMIG is now available by default in the .out file. GROUNDCHECK(DMIG) can be used to deactivate this output.
Frequency response analysis results support in HDF5
The STRESS, STRAIN, and ELFORCE output requests are now supported in Frequency Response Analysis for HDF5 output. The outputs are available in the .h5 file. For more information, refer to the corresponding output request documentation and the HDF5 Data Types in the User Guide.
Additional options for element SET with ELTYPE
In addition to the existing options, the following new options have now been added for ELTYPE: BUSH, CELAS, SPRING, CONM, CMASS, and MASS. For more information, refer to the SET Bulk Data Entry in the Reference Guide.
Limitation removed on number of plies in Large Displacement Nonlinear Static Analysis
The number of plies in Large Displacement Nonlinear Static Analysis was previously limited to 120 plies. This limitation has now been removed.

Resolved Issues

  • The handling of bending stiffness parameter in PSHELL is not correct for Nonlinear Analysis if the non-default value is prescribed in PSHELL.
  • The results from MPI job for Modal Frequency Response Analysis will not be accurate if PARAM,AMSE4EFM,YES is used and if the model has viscous damping.
  • Beam/Bar elements which have the ping flag could be missing in the H3D file for Large Displacement Nonlinear Analysis.
  • Path participation results in the H3D file could be missing for PFPATH Analysis along with the GPFORCE output request.
  • SYSSETTING (TLOADMAT=1) causes a programming error in Frequency Response Analysis.
  • Run time for Modal Transient Analysis has been improved in case SPCF=ALL is defined instead of SPCF=SID.
  • Run time and the disk space requirement for Modal Transient with GPFORCE output request has been improved.
  • Contact area output in the .cntf file was not accurate.
  • The job with DMIGROT would end without any error message.
  • The inaccuracy in GPU jobs has been observed and corrected.
  • PSD and RMS stress for shell elements in Random Response Analysis no longer shows up as “NaN”.
  • AREA output in .cntf file for CONSLI contact was not accurate.