What's New

View new features for OptiStruct 2024.1.

Altair OptiStruct 2024.1 Release Notes

Highlights

  • Cyclic symmetry is now supported for nonlinear analysis
  • Applied temperature through thickness for shell elements
  • General temperature input
  • Honeycomb material for explicit analysis
  • SENSOR activation and action for implicit nonlinear analysis
  • Temperature-dependent MATFAT for Haigh Diagram
  • Slender body aeroelasticity for trim and flutter analysis
  • OptiStruct-EDEM coupling
  • General Python customization
  • Equivalent circuit management for battery thermal modeling

New Features

Stiffness, Strength and Stability
Layer-based STRESS, STRAIN, and OLOAD results for nonlinear implicit analysis
Layer-based STRESS, STRAIN, and OLOAD results are now supported using NDIV=n option on the corresponding output request. It is supported for both small and large Displacement, implicit nonlinear static, and implicit transient analysis.
Initial equivalent plastic strain and back stress via INIPS
Initial equivalent plastic strain and back stress can be defined on the INIPS Bulk Data Entry. They can be defined for both input formats, directly defining the initial plastic strain; the HARD continuation line can be used to define the equivalent plastic strain (EQVPLS), and Back Stress (BKSi) for an element or set of elements. Using the alternate format, the RSTYPE field can be set to HARD to read hardening information including equivalent plastic strain and back stress from an external H3D file, or it can be set to BOTH, which reads the plastic strain tensor along with the equivalent plastic strain and back stress.
Through-thickness temperature definition on shell grid points
The TEMPSEC Bulk Data Entry is now available to define temperatures at grid points or a SET of grid points for determination of thermal loading on shell elements through-thickness. The Ti field can be used to define the temperature at the ith layer. TEMPSEC is supported only for grids associated with shell elements. It is supported in implicit nonlinear static analysis, implicit nonlinear transient analysis, and small and large displacement nonlinear analysis. When multiple temperature values are defined for one grid, the temperature values are assigned to layers that are equally distributed through shell thickness direction from bottom to top. Temperature-dependent material and thermal strain are evaluated at each layer of shell elements as per the temperature definition defined at each section.
Slender body aeroelasticity
Slender bodies (via CAERO2) can now be included in aeroelastic analysis in OptiStruct, along with primary lifting surfaces (via CAERO1). Slender bodies such as fuselages, nacelles, engines, and so on can now be included in the aeroelastic calculations. The CAERO2 Bulk Data Entry defines aerodynamic slender body and interference elements. The PAERO2 Bulk Data Entry defines the cross-sectional properties of slender bodies. This is used for Vortex Lattice Method (VLM) and Doublet Lattice Method (DLM) in subsonic aeroelastic analysis. For CAERO2 slender bodies, the corresponding splines should be defined only using the SPLINE2 linear splines. For CAERO2, the SPLINE2 linear axis is parallel to the X-axis of the aerodynamic coordinate system.
Initial stress output at time 0.0
The initial stress results when mapping is done via the INISTRS entry are now available in the _impl.h3d file. This is output by default for any subcase which contains INISTRS as long as PARAM,IMPLOUT,YES is specified. The output is printed in a separate tensor result type “Initial Element Stresses (2D & 3D)”. For shell elements, only Z1 and Z2 initial stress results are output.
Subcase-dependent material and property
The SELECT continuation line can be defined in the Bulk Data section for the MAT1, MATT1, MATS1, and PBUSH entries to define alternative values for the material and property fields. The new SELECT Subcase Information Entry is available to identify subcase-dependent material and property IDs of the corresponding SELECT continuation lines in the Bulk Data.
Norton creep model
Norton secondary creep model, which is widely used for solder materials, is supported in nonlinear static and nonlinear transient analyses. It is activated by setting the CTYPE field to NORTON on the MATVP Bulk Data Entry. The dH, A, R, n, and thetaZ fields can be used to define the corresponding material parameters (including parameters for stress sensitivities and temperature dependence).
Contact clearance table, including for threaded bolt
A generic contact interface can now be defined which includes both a clearance table and user-defined contact normal for each contact grid/grid SET pair. This can also be used to define a threaded bolt by manually defining the specific contact normal and clearance values. This can be defined using Format B on CLRNC Bulk Data Entry to define the grid/grid SET pairs along with CLEARANCE values and the corresponding normal via NORM_X, NORM_Y, and NORM_Z fields.
Explicit Dynamics Analysis
Through-thickness integration points for PCOMPLS
The number of through-thickness integration points can be defined for PCOMPLS using the NIP field on the EXPLICIT continuation line.
Elastoplastic honeycomb material
A new elastoplastic honeycomb material is now available for explicit analysis. It can be defined using the MATHCOMB Bulk Data Entry. It is used to describe honeycomb and foam with anisotropic behavior. The nonlinear elastoplastic material can be defined separately for normal and shear behavior for the uncompacted configuration, and an isotropic material model is considered for fully compacted material. This is currently supported for solid elements.
MAT9OR material support
The MAT9OR orthotropic material for solid elements is now supported for explicit analysis.
TEMP(INIT) supported with TABLEST for explicit analysis
Initial temperature support was previously available with TABLEMD for explicit analysis. TABLEST support has now been added. The temperature field referenced by TEMP(INIT) is used to look up the temperature-dependent material data on the corresponding TABLEST entry referenced on the MATS1 Bulk Data Entry.
Penalty-based MPC
Penalty-based MPC formulation is turned on automatically in the following cases:
  • When one of the MPC grids is also a dependent grid of an RBE2.
  • When one of the MPC grids is also an independent grid of an RBE2.
  • When the dependent grid of the MPC is also a dependent grid of another MPC.
Auto-contact enhancements for explicit analysis
Auto-contact is now enhanced for explicit analysis:
  • By default, the first surface defined on the ACTIVA continuation line is the secondary surface. A new METHOD field with options SECOND, MAIN, and SYM is available to control the type of surfaces referenced by the ACTIVA continuation line.
  • SECOND continues to be the default, which indicates that the first field is the secondary surface, and the second field is the main surface. MAIN indicates that the first field is the main surface, and SYM indicates that the contact interface to be activated is a symmetric contact.
  • Symmetric contacts are now available by setting METHOD=SYM.
  • The order of surfaces does not matter for DEACTIVA and PCONT continuation lines and similarly does not matter for the case when METHOD=SYM is specified on ACTIVA continuation line.
  • The METHOD field is ignored when self-contact definition is present.
  • Auto-contact can now be defined between the whole model and a particular surface by setting one of ACTID_Ai or ACTID_Bi to ALL and the ID of the particular surface in the other field.
Noise and Vibration
Far-field microphone pressure response can be used to filter peak frequencies via PEAKOUT
The far-field microphone pressure response can now be used to filter peak frequencies by setting the RTYPE field to DISP on the PEAKOUT Bulk Data Entry. This is currently supported for Adaptive Perfectly Matched layer (APML) and Infinite Elements (IE) methods.
Bore distortion calculation for bore definition inside superelements
Bore distortion calculation is now supported for residual runs where the bore definition is internal to the H3D superelements.
PFMODE support for APML
PFMODE is now supported to generate modal participation factors for Adaptive Perfectly Matched Layer (APML) for far-field microphone locations. This includes all PFMODE options including PANELMP which allows for output of Modal participation factors for specific panels.
PFPANEL support for APML
PFPANEL is now supported to generate panel participation factors for Adaptive Perfectly Matched Layer (APML) for far-field microphone locations. PFPANEL for APML is not currently supported for near-field microphone locations. H3D and PUNCH file formats are supported. Participation factors for APML analysis can be requested based on the calculation of pressure (PRESSURE) or acoustic intensity (ACINT).
Control output of reduced fluid cavity in acoustic superelement generation
A new parameter, PARAM,ACMTXNO,YES is now available to skip storing the reduced fluid mass, fluid stiffness, and fluid damping matrices in the acoustic FSI superelements. Only the fluid-structure interface matrix is stored for these acoustic superelements. Assuming that there are N acoustic superelement models which share a single contiguous fluid cavity, then PARAM,ACMTXNO,YES can be added to N-1 of these superelement generation models to avoid storing the reduced fluid mass, fluid stiffness, and fluid damping matrices in all the N-1 superelements. The Nth superelement can be generated without this parameter and these N superelements can now be used in a residual run. These superelements can also be turned into design variables using DMIGDV on CMSMETH. The physical fluid cavity can also be optionally included/excluded in the residual run.
Generalized damping matrix output in flex H3D file
PARAM,MBDDAMP,YES is now available to output generalized damping matrix in the flex H3D file. PARAM,G combined with PARAM,W3 is used to include overall structural damping and PARAM,W4 combined with GE on MAT# entries is used to include element structural damping.
PS field support for fluid GRIDs
The PS field for permanent SPCs on fluid GRIDs is now supported.
Section RESULTANT for random response analysis
Section RESULTANT results are now supported for random response analysis. The resultant PSDF, RMS, and Zero crossing results are output by default. Additionally, the PSDFC option is available on the RESULTANT entry to output additional columns for the cumulative PSDF results and the RMS option is available to only output the RMS and Zero crossing results.
INCLUDE-based energy output
Energy results via ESE, EKE, and EDE can now be output for each INCLUDE file in the model. The following comments apply to this feature:
  • ESE(INCL), EKE(INCL), and EDE(INCL) are available to output INCLUDE file-based energy output in addition to element-based energy output.
  • ESE(OINCL), EKE(OINCL), and EDE(OINCL) are available to output only the INCLUDE file-based energy output.
  • This is supported for linear static, normal modes, complex eigenvalue, and frequency response analyses.
  • This is supported for both H3D and PUNCH output formats.
  • The corresponding elements in each include file in the model are automatically collected as element SETs of SUBTYPE=PROP where applicable, and SUBTYPE=ELEM otherwise. These internally created element SETs are saved in the filename_sets.inc file which can be used for review.
Fatigue
Temperature-dependent MATFAT for Haigh Diagram
The MATFATT Bulk Data Entry is now available to define temperature-dependent Haigh-diagrams. Only one Haigh-diagram is currently supported per temperature. The MATFATT Bulk Data Entry should have an ID that matches the ID of a base MATFAT entry. The TEMPUNIT field can define the temperature unit (Celsius or Fahrenheit).
Spectral moment calculation control for random response fatigue
A new parameter PARAM,FRACMMNT is now available to define a fractional real number (between 0.0 and 1.0) which defines the percentage of m0 moment. The upper limit of the frequency is then calculated as the frequency up to which the PSD stress is integrated to reach PARAM,FRACMMNT fraction of the corresponding m0 value, that is calculated by integrating through 100% of the frequency range. Subsequently, spectral moments are now calculated by integrating the PSD stresses up to the calculated upper limit of frequency.
Read external stresses for fatigue analysis
External stresses can now be used to conduct fatigue analysis:
  • The ASSIGN,UNV,ID,filename entry can be used to identify the external file and assign it an ID.
  • The EXTSTRS continuation line on FATEVNT Bulk Data Entries can be used to identify the ID of the external file associated with the corresponding ASSIGN entry.
  • The SCALE field on the EXTSTRS continuation line can be used to scale the stresses.
MultiPhysics
OptiStruct-EDEM coupling for bulk and granular material interaction with structures
OptiStruct-EDEM coupling allows for coupling the advanced structural analysis capabilities of OptiStruct with bulk and granular material interaction capabilities of EDEM. You can simulate and analyze the interaction of materials such as coal, soils, grains, and so on with deformable surfaces. It is currently only supported with explicit dynamic analysis (NLEXPL) subcases. OptiStruct transmits nodal coordinates and velocity to EDEM, while EDEM sends nodal forces to OptiStruct during the coupling. It is important to make sure that the unit systems defined in both OptiStruct and EDEM are consistent. For OptiStruct-EDEM coupling runs, it is mandatory in OptiStruct to define the UNITS Subcase Information Entry to identify the model units and that this identified units system is consistent with the units system defined in EDEM. The particle type, material, interaction physics data should be defined in the EDEM model.

Additionally, the OptiStruct-EDEM interface surface material information should be defined both in OptiStruct and EDEM and they should be consistent with each other. In OptiStruct, the interface surface material data is used to calculate the deformation behavior of surface, while in EDEM, the interface surface material data (defined under Equipment Material) is used to calculate the contact forces during the interaction between the particles and the surface. The time-history output of OptiStruct-EDEM coupling forces are output to the filename_TH.h5 file and it can be activated via the THIST entry, with a new EDEM continuation line with FX, FY, FZ, and F options.

Equivalent circuit modeling for battery thermal management
Equivalent circuit modeling is now available for battery thermal management. The battery cells can be represented using the BCELL Bulk Data Entries for transient electrical conduction analysis. The corresponding MCELL Bulk Data Entry can be used to define battery cell material definition, which includes defining the number of resistance-capacitor pairs charge status, discharge status, and initial polarized voltage.

The resistance, capacitance, and open circuit voltage of the battery components can be constant (TCFLAG=1) or dependent on temperature and state of charge (TCFLAG=2). The PCELL property entry can be used to define the initial state of charge of the battery elements and capacity of the battery cell. The battery module can be defined using the MODULE Bulk Data Entry which specifies the number of battery cells and the way they are connected (series vs parallel) and corresponding module loading types. The OUTPUT,CELLHEAT,YES command outputs dedicated ASCII files or ECM parameters and Bernardi Equation QVOL values.

Optimization
Optimization constraint bounds as a relative ratio
The optimization constraint bounds on the DCONSTR entry can be defined as the relative ratio of the response value at a particular iteration and the corresponding value of the response at iteration 0. This is activated by setting the 9th field on DCONSTR entry to RATIO. It is supported for all responses across DRESP1, DRESP2, and DRESP3. For iteration 0 in the .out file response summary, the original RATIO bounds are printed as the actual bounds are not known yet. The actual bounds are printed starting from iteration 1.
Level-set optimization now supports obstacle definition in conjunction with draw-direction constraint
Level-set optimization now supports obstacle definition (OBST continuation line on DTPL), in conjunction with draw-direction constraint (DRAW continuation line on DTPL).
SET-based obstacle definition on DTPL
Obstacle definition on the DTPL entry can now also be defined using SETs (in addition to properties). The first field following the OBST flag should be set to SET and the subsequent fields can contain a list of SET IDs that represent the obstacle.
MAXDIM support with draw-direction constraint for level-set optimization
MAXDIM is now supported with draw-direction constraint for level-set optimization.
General
Composite shell CORNER results
For shell elements with composite properties, corner results are available for CSTRAIN, CSTRESS, and CFAILURE with the CORNER option.
REPCASE support enhancements
REPCASE is now supported for all solution sequences.
General temperature support via TEMPG
The TEMPG Subcase Information Entry is now available. Compared to the traditional TEMP entry, with general temperature via TEMPG you can define:
  • Subcase-dependent material temperature via TEMPG(MAT)
  • Subcase-dependent initial temperature via TEMPG(INIT) in static and transient analysis.
  • Subcase-dependent loading via TEMPG(LOAD).
General temperature via TEMPG cannot be defined with TEMP in the same model.
TEMPG is supported for:
  • Linear static analysis
  • Normal modes analysis
  • Linear transient analysis
  • Frequency-response analysis
  • Nonlinear implicit (nonlinear static and nonlinear transient)
  • Explicit dynamics (only subcase-independent TEMPG is supported for this currently)
Initial stress enhanced with RELOC support
The RELOC continuation line is now available for the case where initial stress results are sourced from an external file (.k file). The MATCH and MIRROR options are available via the RTYPE field.
Nonlinear analysis support for cyclic symmetry
Previously cyclic symmetry was supported for:
  • Linear static analysis
  • Normal modes analysis
Cyclic symmetry is now also supported for:
  • Implicit nonlinear static analysis
  • Implicit nonlinear transient analysis
  • Prestressed analysis (preloading subcase should be either linear static or implicit nonlinear static)
The following comments apply to nonlinear analysis support for cyclic symmetry:
  • Non-cyclic symmetric loading or behavior is not supported for nonlinear cyclic symmetry subcases.
  • Therefore, regular loading can be applied such as direct via LOAD/LOADADD/DLOAD in the Subcase section.
  • For prestressed analysis, the preloading subcase should be completely cyclic symmetric.
Back stress output
Back stress output via STRESS(BACK)=ALL is now supported for implicit small and large displacement nonlinear analysis, and for explicit dynamic analysis for solids, shells, and continuum shells for kinematic hardening and mixed hardening. It is supported for both regular H3D and on-the-fly H3D files.
Strain output enhancements for implicit nonlinear analysis
The STRAIN(TOTAL=YES/NO) options are now supported to control the output of total strain tensor. The STRAIN(PLASTIC=YES/NO/EQPS) options are now available to control the output of plastic strain tensor and/or equivalent plastic strain. These options are supported for implicit nonlinear static analysis and implicit nonlinear transient analysis for both the regular H3D and on-the-fly H3D files.
Enhanced output control for nonlinear _nl.h3d file used in monitoring
The OVERWRITE=YES option on NLMON Bulk Data Entry or PARAM,NLMON,DISP,OVERWRITE can now be specified to overwrite the results of the previous increment from the current/latest increment. Additionally, each subcase has its own separate _nl_sub#.h3d file (which contains the results data) and a single _nl_model.h3d file (which contains the model data).
Rotation output control for HDF5 output
Rotation output can be turned on using DISP(ROTA,HDF5)=YES for HDF5 output. The NOROTA option is the default.
FLAT option supported for TABLEST entry
The FLAT option is now supported on the 5th field of the TABLEST entry. The default is FLAT=0, which indicates that if an x-value input is outside the range of x-values specified on the table, the corresponding y-value look up is performed using linear extrapolation from the two start or two end points. The FLAT=1/FLAT option indicates that if an x-value input is outside the range of x-values specified on the table, the corresponding y-value is equal to the start or end points, respectively.
SET-based output for ENDLOAD and PARAM,XPOST
SET-based output is now supported via ENDLOAD=SETID and PARAM,XPOST,YES/NO/NOFORCE,SETID, where SETID is the ID of an Element SET. Edges are automatically detected based on the defined element SETs, and contribution is included from all the elements attached to these edges (even if there are elements attached to these edges that are not part of the defined element SET).
SENSOR enhancements for nonlinear implicit analyses
Displacement, SPC force, and force-based sensors are available via the SENSOR Bulk Data Entry. An additional sensor sub-type of SECTION force is available for the force-based sensor. Three condition types are supported, such as BOUND, which defines the sensor bounds, SLOPE, which defines the time-gradient sensor bounds, and DROP, which defines the lower bound of the difference between the maximum value of the sensor and the current sensor value. Once these sensors are triggered, the following actions are available: WARN, which issues a warning and the solution continues, and ERROR, which stops the current subcase and an ERROR is issued. This is supported for implicit nonlinear static analysis and implicit nonlinear transient analysis.
SPCFORCE output for user-defined coordinate system
The CID=# argument is now supported for the SPCFORCE output request to identify the ID of a user-defined local coordinate system in which the SPCF results are output to the .spcf file (OPTI format). This is supported for linear static and nonlinear static analyses. If present, the SPCFORCE results in the OPTI format (.spcf file) additionally contain the SUM-ALL-U SPCFORCE results which is the sum of SPC force in the user-defined coordinate system defined via the ID field. The corresponding sum of SPC force in the basic coordinate system is also output as SUM-ALL-B.
BLOCKPARAM with user-defined ERROR messages
User-defined ERROR messages can be included with BLOCKPARAM within the OptiStruct configuration file. The user-defined ERROR messages can be defined after the end of the BLOCKPARAM line beginning with a “#”. OptiStruct automatically formats the ERROR messages so that they fit within 80 columns in the .out file. You can also pre-format the ERROR messages using the “|” symbol to split the lines.
JOINTG output coordinate system
JOINTG results are output by default in the local elemental coordinate system of the joint (this is co-rotational). To output the corresponding results globally for all JOINTGs in the basic system, a new BASIC argument is now available to the JOINTF and JOINTD output requests.
Enhanced mapping control for initial stress from external files
A new MAP field is now available on the INISTRS Bulk Data Entry. The MAP field can be set to AUTO (which is the default) so that the initial stresses are mapped when the external “.k” file has geometry data (element and grid data). If the external file does not have geometry data, simple element ID search is conducted by assuming that the external results file also contains the same element IDs as the OptiStruct input file. If element IDs are not found, the job stops and an ERROR is issued. If the MAP field is set to ID, a simple element ID search is conducted by assuming that the external results file also contains the same element IDs as the OptiStruct results file, even if the external results file contains geometry data. This can improve performance when it is known that there is geometry and element ID match with the external file.
Implicit nonlinear on-the-fly H3D output
The following enhancements are implemented for implicit nonlinear on-the-fly H3D output:
  • GPFORCE element results are supported
  • Temperature results are supported.
Multiple results output for the same output request
Various enhancements have now been made for creating multiple outputs of the same output type. The current coverage for this feature as of the OptiStruct 2024.1 release is as follows:
  • For the same output, multiple requests can now be specified with different options, such as SET IDs, result types, such as VON, DIRECT and so on.
  • For each such output request, the FILE=filename option can be specified to identify the separate filename to which this result is output. Output with different options can be printed to different files or to the same file, based on the specified filename in the FILE=filename option.
  • The SUFF=string option can be specified instead of the FILE=filename option. In this case, the string is used as a suffix instead of replacing the filename.
  • The SYSSETTING(MULTIPLEOUTPUT=YES) option should be specified to activate this feature.
  • It is currently supported for:
    • Linear static, normal modes, direct and modal frequency response, direct and modal transient response, direct and modal complex eigenvalue, and random response analyses types.
    • The H3D, OP2, PUNCH, and OPTI formats are supported.

      H3D: All output requests already supported for the listed solution types are also supported for multiple output.

      OP2: All output requests already supported for the listed solution types are also supported for multiple output. The FILE=filename option is only supported for linear static analysis for OP2 format.

      PUNCH: Supported for displacement, velocity, acceleration, stress, strain, and force outputs.

      OPTI: Supported for displacement, velocity, acceleration, stress, strain, and force outputs.

    • For implicit nonlinear static analysis, the older method for multiple output support, which can now be activated via SYSSETTING(MULTIPLEOUTPUT=STRESS), continues to be available. If SYSSETTING(MULTIPLEOUTPUT=YES) is specified in a model with nonlinear implicit static, it is internally switched to SYSSETTING(MULTIPLEOUTPUT=STRESS) and the corresponding supported output is generated.
HDF5 output support
HDF5 output support has been significantly enhanced. Support is now available for:
  • Linear static: DISP, STRESS, STRAIN, FORCE, GPFORCE, SPCF, MPCF, JOINTG (DISP, FORCE, Reaction FORCE, Stop-Lock Status, Viscous Damping Force, Elastic Force).
  • Normal modes: ESE, Eigenvector, STRESS, STRAIN, GPFORCE, SPCF, MPCF, JOINTG (DISP, FORCE).
  • Frequency response: DISP, VELOCITY, ACCELERATION, STRESS, STRAIN, GPFORCE, SPCF, MPCF, SDISP, SVELO, SACCE, ESE, JOINTG (DISP, FORCE)
  • Linear transient: DISP, VELOCITY, ACCELERATION, STRESS, STRAIN, MPCF, SDISP, SVELO, SACCE, ESE
  • Nonlinear implicit static, nonlinear implicit transient: DISP, STRESS, STRAIN, MPCF, SPCF, OLOAD, GPF, JOINTG (DISP, FORCE, Reaction FORCE, Stop-Lock Status, Viscous Damping Force, Elastic Force). These results are supported both for regular HDF5 and on-the-fly HDF5 files.
  • Random response: DISP, SPCF
Python with LOADLIB
Python can now be used to write any user-defined code for DRESP3, MATUSR, MATUSHT, QVOL, PCONV, QBDY, or SPCD which can then be used with LOADLIB within OptiStruct. The functions and the corresponding arguments are similar to the ones which were already supported for Fortran/C/C++-based code used with LOADLIB. The path in LOADLIB should point to a Python file ending with “.py” to run Python with LOADLIB.
General Python customization
Python can now be used to access any module within OptiStruct. Any “MODULE” within the .stat file can be accessed by Python. You can access modules using the following steps:
  • The ASSIGN,PYFILE,filename.py can be included in the OptiStruct .fem file to load the Python script. Single or multiple Python scripts can be defined in a single OptiStruct model.
  • The Python script should contain the “import optistruct” command. This module defines the functions and classes which give the script access to OptiStruct data.
  • Functions can then be written inside the Python script, and these functions can be assigned as callbacks using the optistruct.hook() function. To assign such a callback, the module name into which you wish to hook should be specified (this is the module inside OptiStruct where this new python function is called). This module can be any MODULE listed in the .stat file.
  • The Python function you define in this way is called at the end of the module defined in the corresponding optistruct.hook() function.
  • For example, if you write a function named “elemchk”, and wish to call it at the end of the OptiStruct CHECKEL module, you can assign the function “elemchk” as a callback using: 
    optistruct.hook('CHECKEL', elemchk)

Enhancements

Linux version of OptiStruct 2024.1
  • The supported operating systems are Red Hat version 8.4 and above, Rocky Linux version 8.4, or CentOS 8.4 and above. Older Linux operating systems should be upgraded to run OptiStruct 2024.1.
  • The Intel MPI version is upgraded to 2021.12.
  • The alternate H3D version executable is upgraded from H3D 22 to H3D 23.
  • The regular H3D version remains at H3D 14.
Windows version of OptiStruct 2024.1
  • The alternate H3D version executable is upgraded from H3D 22 to H3D 23. The regular H3D version remains at H3D 14.

Resolved Issues

  • Normal modes analysis results were incorrect when CTRIA6 membrane elements were included in the model. Now, second-order CTRIA6 element formulation is improved for accuracy for all analysis types.
  • Results are now correct for thinner shells when PARAM,CURVSHL2,THICK was used.
  • Optimization results are now correct when thickness gradient constraints are applied on DSIZE entries, and manufacturing constraints are applied to all DSIZE entries.
  • Results are now correct for torsion modes of beam elements in a preloaded modal analysis when the preloading subcase contains RFORCE loading.
  • Out-of-plane shear stiffness is now considered for MATMDS with a laminate.
  • For Multi-Model Optimization (MMO), the sensitivity results for DRESP2 and DRESP3 responses defined in the main model are now available.
  • Velocity and acceleration results are now correct when the DELAY option is applied on a TLOAD2 load for enforced displacement/velocity loaded models for nonlinear transient analysis.
  • Displacement, velocity, and acceleration results are now correct when TLOAD2 is used for certain enforced displacement loaded models for nonlinear explicit analysis.
  • Multiple enhancements have been included for Grid Point Force results for both regular and on-the-fly outputs.
  • WARNING #3019 for TABLES1 data is now revised to accurately reflect the nature of the specified curve.
  • Performance improvement for MPCADD is now available for explicit analysis.
  • A crash no longer occurs when the MATFATT entry is specified without TEMP(MAT).
  • Corner strain results for plane stress shell elements are now correct when other element types are also present in the model.
  • Loading performance issues and errors no longer occur with the THIST-based HDF5 output file when loading into HyperGraph.
  • Point loads were are now correctly processed for frequency response subcases if gravity loading is defined in the model.
  • Performance is improved for multi-level DDM in sequentially coupled thermal-structural analysis.

Altair OptiStruct 2024 Release Notes

Highlights

  • Multiple Results Output for the same Output request
  • Temperature-dependent Cohesive Material
  • Johnson-Cook Failure Criterion for Explicit Analysis
  • Hyperelastic materials for shells in Explicit analysis
  • Global-Local Analysis support for Direct and Modal Transient Analysis
  • Fully Coupled Electro-Thermal-Mechanical Analysis
  • ESL Optimization for Transient Analysis
  • SLIPRING joint for Implicit Nonlinear Analysis

New Features

Stiffness, Strength and Stability
Skip non-FREEZE contact in Linear Analysis
Contact interfaces which are non-FREEZE/non-TIE can now be deactivated in Linear Analysis using CONTPRM,DEACTLIN,NOTFRZ. This applies to any linear analysis subcase which does not contain NLSTAT preloading. The default (CONTPRM,DEACTLIN,NONE) continues to retain all CONTACT interfaces in linear analysis.
Linear Elastic property from Nonlinear Explicit material in Implicit Analysis
Certain Nonlinear materials such as Johnson-Cook, Crushable Foam, Cowper-Symonds, and Johnson-Holmquist materials are currently only supported for Explicit analysis. Now for these materials, if present in Implicit analyses, then only the corresponding linear elastic part of these materials are used for these non-Explicit analysis types. This also allows the use of these material models in models which contain both Implicit and Explicit analysis subcases.
Temperature-dependent Cohesive Material
Temperature-dependent Cohesive materials are now supported. The following properties can now be temperature-dependent:
  • The elasticity moduli for Mode I, Mode II, and Mode III deformation modes can now be temperature-dependent and are specified using the KI_i, KII_i, KIII_i fields for each corresponding temperature value of X_i on the MCOHED Bulk Data.
  • The maximum values of strain or traction depending on the cohesive damage initiation type can now be temperature-dependent and can be specified via the V1_i, V2_i, and V3_i fields for each corresponding temperature value of X_i on the DMGINI Bulk Data.
  • The corresponding Damage evolution curves, defined via ALPHA_i and W1_i, W2_i, W3_i parameters can now be temperature-dependent for each corresponding temperature value of X_i on the DMGEVO Bulk Data.
SLIPRING for JOINTG for Implicit Nonlinear Analysis
SLIPRING has already been available in the previous release for Explicit analysis. This is now available also for Implicit analysis. SLIPRING is available on the JOINTG Bulk Data Entry to model belt and pulley joints. Linear and Nonlinear Elasticity, Friction and Friction Angle, Mass and Damping are considered properties for SLIPRING joints. It is now supported for large displacement implicit nonlinear static/transient analysis and Explicit Dynamic analysis. JTYPE on JOINTG entry should be set to SLIPRING and various properties can be defined for DOF 1 for the slipring joint using the ELAS, NELA, FRIC, MASS, and DAMP property types on the PJOINTG entry. SLIPRING has an additional degree of freedom, flow, which is unique for this joint type.
Kinematic Hardening and Mixed Hardening for Plane Stress Elements
Kinematic Hardening (HR=2 on MATS1 Bulk Data) and Mixed Hardening (HR=3) are now supported for Plane Stress Elements (CTPSTS and CQPSTS) for both Small and Large displacement nonlinear analysis.
Explicit Dynamic Analysis
TEMP(INIT) support for Explicit Analysis
Initial temperature support is now supported for Explicit Analysis. TEMP(INIT) can point to a TEMP/TEMPD Bulk Entry which identifies the initial temperature field. This temperature field is used to look up the temperature-dependent material data on the corresponding TABLEMD entry referenced on the MATS1 Bulk Data.
MPC support for Explicit DDM
MPCs were already supported for SMP jobs for Explicit Dynamic Analysis in previous versions of OptiStruct. MPCs are now additionally supported for Domain Decomposition method (DDM) for Explicit Analysis.
Johnson-Cook Failure Criterion for Explicit Analysis
Johnson-Cook Failure Criterion for elasto-plastic material failure for stress triaxiality effect is now supported for Explicit Analysis. It considers an exponential decrease of the material ductility with increasing stress triaxiality. It can be activated by setting CRITERIA field to JOHNSON on the MATF Bulk Data Entry. The Johnson-Cook parameters D1, D2, and D3 can be defined via the V1, V2, and V3 fields on the MATF Bulk Data Entry.
Enhancement to PLAS Failure Criterion for Explicit Analysis
The maximum plastic strain (PLAS) failure criterion for Explicit analysis has now been enhanced:
  • Previously, PLAS criterion was only based on a constant maximum equivalent plastic strain value at failure (defined via V1 field).
  • This failure criterion has now been enhanced by adding:
    • Failure based on thinning strain (defined via V2 field) and its interpretation depends of the sign of the input value. If V2 > 0.0, then it corresponds to εzz total strain (ZZ component of the total strain tensor), or if V2 < 0.0, then it corresponds to εzz plastic strain (ZZ component of the plastic strain tensor).
    • Failure based on major strain (defined via V3 field). It is the failure computed based on the maximum positive value of the principal total strains. If multiple options are specified together for PLAS option, then the maximum damage is retained for the output
Hyper-elastic Materials for shell elements in Explicit Analysis
Hyper-elastic materials are now supported for shell elements in Explicit analysis. Hyper-elastic materials were already previously supported for shell elements in Implicit analysis.
Edge-to-Edge contact turned off by default for shells in Auto-Contact for Explicit analysis
Edge Criteria default for shell elements in auto-contact has now been changed from 45.0 degrees to 179.0 degrees. This basically turns off edge-to-edge contact by default, which can help improve performance as the edge is not considered. Note that the shell element boundary edges are still considered. The default remains 45.0 degrees for solid elements.
Switch the default element formulation for first order TETRA elements in Explicit Analysis
The default element formulation for first order CTETRA elements has now been switched from nodal pressure averaged formulation to 1 point formulation in Explicit Analysis.
Penalty-based RBE3 supported
Penalty-based RBE3 is now supported for Explicit analysis. The traditional kinematic RBE3 formulation is automatically switched to the Penalty-based RBE3 formulation in the following cases:
  • Incompatibility (Over-constraint): When Reference grid of RBE3 is also:
    • Dependent grid of an RBE2
    • Secondary side grid of TIE
    • Part of SPC
  • Hierarchical RBE3s exist:
    • Wherein the Reference grid of an RBE3 is also the independent grid of another RBE3.
  • Hierarchical RBE3 and RBE2 exist:
    • Wherein the Reference grid of an RBE3 is also the independent grid of another RBE2.
Noise and Vibration
Significant reduction in disk space usage for Superelement generation runs using AMSES
The disk space usage of Superelement generation runs using AMSES has been significantly improved. This will allow for less resource usage and disk I/O requirements. Note that PARAM,AMSE4CMS,YES should be active (which is active by default).
GPU Support for Direct Frequency Response Analysis
GPU Support is now available for Direct Frequency Response Analysis.
Reflective Surface outside External Acoustic Cavity for APML External Acoustics
Reflective surfaces can now be defined outside the External Acoustic cavity for APML. The reflective planes are defined perpendicular to the location on the corresponding axis defined by the XRFL, YRFL, and ZRFL fields on the PACPML Bulk Data. There can only be 1 reflection plane perpendicular to each axis. The corresponding reflection factor for each of the reflection planes can be defined by the XFAC, YFAC, and ZFAC fields of the PACPML Bulk Data. The contribution of the reflection planes to far field pressure can be calculated based on the mirror rule incorporating the corresponding reflection factor.
Preloading support for Response Spectrum Analysis
Preloading is now supported for Response Spectrum Analysis. The STATSUB(PRELOAD) entry can be defined in the Response Spectrum subcase and it can point to the corresponding preloading subcase.
Absolute Maximum Principal Strain output for Random Response Analysis
Absolute Maximum Principal Stress output has already been available in previous versions when PARAM,PSDPRINC,YES in H3D format. Similarly, PARAM,PSDPRINC,YES now also activates output for Absolute Maximum Principal Strain output in H3D format for random response analysis.
Enhanced AMSES performance for MPI runs
AMSES performance has now been enhanced for both single-node and multi-node MPI runs. The improvement in performance shows good scaling when compared to the previous versions of OptiStruct for AMSES when run in DDM mode. The following explains in more detail about the feature by providing a simple example:
  • For single-node runs, where a model which uses AMSES for eigen-extraction is run in DDM mode, assuming the run configuration is 1x8x4, where the model runs with 8 MPI processes and 4 SMP threads on a single node, then when AMSES solver starts, the main MPI process will suspend the remaining 7 MPI processes and deploy AMSES to run on all physical cores on the node which were available for the job. In this case, 8x4=32 cores are now available for the AMSES run and AMSES will run on 32 cores SMP until the eigen-extraction is done. Then the main MPI process will revive the other 7 MPI processes and the DDM job continues normally from this point.
  • For multi-node runs, where a model which uses AMSES for eigen-extraction is run in DDM mode, assuming the run configuration is 2x8x4, where the model runs with 8 MPI processes and 4 SMP threads on each node of a 2-node cluster, then when AMSES solver starts, the main MPI process will suspend the remaining 15 MPI processes across both nodes and deploy AMSES to run on the node where the main MPI process runs and will use all physical cores on this node which were available for the job. In this case, on the node where the main MPI process runs, 8x4=32 cores are now available for the AMSES run and AMSES will run on 32 cores SMP until the eigen-extraction is done. Then the main MPI process will revive the other 15 MPI processes which were spread across the 2 nodes and the DDM job continues normally from this point.
Note that running AMSES under DDM mode can lead to some overhead due to communication between the secondary MPI processes and the main MPI process to retrieve the local matrices for AMSES to be run on the main MPI process. Therefore, AMSES may still be run optimally on pure SMP mode, but for cases where models using AMSES need to be run in DDM mode (like when there are NLSTAT preloading subcases), then it can help improve AMSES performance by allowing it to use all available physical cores on the node containing the main MPI process.
Fluid Grid loading now supported in OLOAD output
Fluid Grid loading via SLOAD, ACSRCE load is now output when OLOAD I/O Entry is specified.
Fatigue
Fatigue Analysis based on Steady-State subcase
Fatigue Analysis can now be performed based on a Steady-State Subcase. The LCID field on the FATLOAD entry should point to a Steady-State subcase to activate Fatigue with steady-state analysis. The TID field on the FATLOAD entry should be left blank.
MultiPhysics
Joule Output based on property, component, and SET
Joule loss density output has already been available via the HEAT I/O Entry for electrical analysis. Now the property/component/SET-based outputs are now included with the corresponding grid-based output via the PROP, COMP, and SET group options in the HEAT I/O Entry. Similarly, OPROP, OCOMP, and OSET options outputs only property, component, and SET-based output, respectively. This is currently only supported for H3D format.
Electrical Contact is now defined using Conductance per unit Area
Previously, the electrical contact definition via PCONTEC and PGAPEC were specified using resistance per unit area. This has now been switched to Conductance per unit area.
Fully Coupled Electro Thermal Mechanical Analysis
Electrical, Thermal, and Mechanical subcases can now be fully coupled. For this purpose, connectivity is updated in the electrical and thermal domains, based on the results of the mechanical domain. After a subsequent electrical analysis, Joule heating, as well as mechanical induced heating (for example, inelastic strain), is considered during a thermal analysis. The resulting temperature field is in turn used to update the temperature-dependent material properties and to compute thermal expansion in the mechanical analysis. The subcases which can be coupled are:
  • Nonlinear Implicit (Static or Transient) structural subcase
  • Nonlinear Transient Heat Transfer subcase
  • Multi-Steady Electrical Analysis subcase
The COUPLE(HEAT)=<ID> entry should be specified within the Nonlinear Direct Transient subcase where the ID points to the subcase ID of the Nonlinear Transient Heat Transfer subcase to be coupled. Similarly, the COUPLE(ELEC)=<ID> entry should also be specified in the Nonlinear Direct Transient subcase where the ID points to the subcase ID of the Multi-Steady Electrical Analysis. Note that COUPLE(ELEC) and COUPLE(HEAT) can also be used separately for corresponding coupling.
For electrical subcase in coupling, DDM is currently not supported. For heat-transfer subcase, cavity radiation is not currently supported. For structural subcase, NLCTRL is mandatory for this coupling (NLPARM is not supported).
When coupled, all results, including results for heat transfer and electrical subcase are printed to the _impl.h3d file which is generated from the Nonlinear Direct Transient subcase. PARAM,IMPLOUT,YES should be specified.
Optimization
Sensitivity output for Free-Shape Optimization
Sensitivity output is now supported for Free-Shape optimization. It can be activated using OUTPUT,H3DSHAPE. The ALL, STRESS, and NOSTRESS options are supported.
Enhancements for Draw Direction with thickness gradient Constraint in Free-Size optimization
Draw Direction with thickness gradient constraint in free-size optimization has now been made more robust and additionally enhanced with more options. The Draw direction along which the thickness gradient is to be applied should typically be orthogonal to the rib shell element normals, and OptiStruct, by default, checks the draw direction by comparing it to the element normals (within a specific tolerance). Based on this check, OptiStruct will issue an ERROR if the user-defined draw direction is beyond the specified tolerance.
Figure 1.


The COPT field on DSIZE entry can be set to:
  • CHECK: (Default) Checks the draw direction
  • ADJUST: Checks and adjusts the draw direction
  • SKIP: Does not check the draw direction
If COPT is set to CHECK, OptiStruct will check the draw direction, and:
  • Issue an ERROR if it is beyond the specified tolerance.
If COPT is set to ADJUST, OptiStruct will check the draw direction, and:
  • Adjust the draw direction, as long as it is within the specified tolerance.
  • Adjust the draw direction, and then issue an ERROR if the adjustment value was more than the specified tolerance
The TOLDIR field is the tolerance (in degrees, default=5.0) for the user-defined draw direction.
The TOLBOT field is the tolerance (in degrees, default=10.0) to determine if a side edge should be treated as a bottom edge.
The TOLTOP field is the tolerance (in degrees, default=10.0) to determine if a side edge should be treated as a top edge. If the angle between an edge and the draw direction is lower than TOLBOT/TOLTOP, then it is considered as a side edge.
ESL optimization for Transient Analysis
The Equivalent Static Loads (ESL) method can now be employed within OptiStruct to solve linear transient optimization problems. The ESL method creates a number of equivalent linear static auxiliary sub-problems based on the solution of the corresponding Linear Transient analysis. Those auxiliary problems are solved in a nested loop. The analysis and the nested loop are repeated in an outer loop until convergence is achieved.
Supported analysis types are:
  • Linear Direct Transient Response (DTRAN)
  • Linear Modal Transient Response (MTRAN)
The method is activated using DOPTPRM,NESLOPT,#ET, where #ET specifies the number of ESL auxiliary load-cases created. The time represented by each auxiliary load case can be specified using the ESLTIME card, for example, such that the extremes of a specified response are captured. Moreover, the parameters DOPTPRM,DESMAX and DOPTPRM,ESLMAX control the maximum number of outer loops. Currently, Stresses, Displacement and Compliance are supported as responses.
Note: The number of ESL-times should be kept low to enhance runtime performance.
General
Multiple Results Output for the same Output request
Multiple outputs of the same output type can now be requested for single or multiple subcases. The following options are now supported.
  • For the same output, multiple requests can now be specified, with different options, such as SET IDs, result types, such as VON, DIRECT and so on.
  • For each such output request, the FILE=filename option should be specified to identify the separate filename to which this result is to be output. Output with different options can be printed to different files or to the same file, based on the specified filename in the FILE=filename option. The FILE option is not currently supported for OP2 format.
  • The SYSSETTING(MULTIPLEOUTPUT=YES) option should be specified to activate this feature.
  • It is currently supported for:
    • Linear static, normal modes, direct and modal frequency response, direct and modal transient response analyses types.
    • Displacement, Stress, Strain, and Force results.
    • The H3D, OP2, PUNCH, and OPTI formats.
SDISP, SVELO, and SACCE output for HDF5 format
SDISP, SVELO, and SACCE outputs are now supported in HDF5 format for Modal Frequency Response and Modal Transient Response analyses. These were already supported in H3D, OP2, and PUNCH formats in previous releases.
Global-Local Analysis is now supported for Direct and Modal Transient Analyses
Both combinations are supported, but the majority of use-cases would likely be Modal Transient in the global model and Direct Transient in the local model. Currently only the two-step modelling approach is supported. The results from the global model are imported from the H3D file using ASSIGN,H3DRES. The specific subcase in the global model from which the results are to be imported is specified using IMPORT,SUB. A grid SET is created in the local model to identify the interface/transfer zone and SPCD is defined on these grids with field D set to M to indicate that they are used for mapping. Since this is transient analysis, the SPCD should be referenced by TLOAD1 entries.
Threshold Support for STRAIN output
Threshold options RTHRESH, THRESH, RTOP, and TOP are now supported for STRAIN output. This is supported for both Total and Neuber strain. It is currently supported for H3D format only. It is supported for Linear Static, Nonlinear Static, Normal modes, Frequency response, and Transient analyses.
Threshold Support for Neuber STRESS output
Threshold options RTHRESH, THRESH, RTOP, and TOP are now supported for Neuber STRESS output. Note that threshold options were already supported for stress output without Neuber in previous releases. It is currently supported for H3D format only. It is supported for Linear Static, Nonlinear Static, Normal modes, Frequency response, and Transient analyses.
Statistics output for STRAIN output in Linear Transient Analysis
Statistics output for STRAIN output is now supported for both direct and modal Linear Transient Analysis. This is supported for both total strain and Neuber strain. They are activated using the STATIS or OSTATIS options. STATIS output regular strain along with statistics over time, while OSTATIS outputs only statistics over time.
Statistics output for ERP output in Linear Transient Analysis and Steady-State Analysis
Statistics output for ERP output is now supported for both direct and modal Linear Transient Analysis and Steady-State analysis. They are activated using the STATIS or OSTATIS options. STATIS output regular ERP along with statistics over time, while OSTATIS outputs only statistics over time. This is currently only supported for H3D format.
Applied Temperature output via OLOAD for HDF5 format
Applied temperature load output is now supported for HDF5 format when OLOAD is defined in Linear Static analysis. If additional structural loads exist along with temperature load, then they are also output along with the applied temperature load output.
MAT8 Output in HDF5 format
When any HDF5 specific output request is defined in the model, for example, DISP(HDF5)=ALL, or if OUTPUT,HDF5,YES is defined, in a model which contains MAT8 material, then this MAT8 material is output to the HDF5 file.
Energy output for Linear Static analysis with Neuber correction
Energy output is now available for Linear Static analysis with Neuber correction. The NLENRG Bulk/Subcase pair can be used in Linear Static analysis where Neuber correction is used. Note that the NLENRG Subcase Entry should have an additional NLENRG(NEUBER)=ID option defined for this output. The internal energy and plastic dissipation energy values for the full model and/or the specified element SET in the filename_e.out file.

Resolved Issues

  • For Explicit Auto-Contact, the specified PCONT with specific ID will be used now for the particular contact interface, even if PCONT with option ALL is defined.
  • Only Large Displacement nonlinear analysis is supported for OptiStruct-AcuSolve FSI coupling. Previously, using small displacement nonlinear analysis would lead to incorrect results. This has now been fixed by printing a clear error requesting the user to switch to large displacement nonlinear analysis in OptiStruct.
  • The following issues were resolved for Draw Direction in free-size optimization:
    • For ribs which contain overhangs, there are multiple bottom and/or top edges along the draw direction. This is now properly handled and the correct base is now identified for such ribs.
    • Unpredictable results could be previously observed when DSIZE with Draw-direction was combined with another DSIZE without any manufacturing constraints. This has now been fixed.
    • A crash or unpredictable results were previously observed when DSIZE with regular draw-direction and DSIZE with draw-direction with thickness gradient optimization were combined in the same model. This has now been fixed.
  • An explicit analysis model with TIE contact previously crashed with data manager check. This has now been fixed.
  • The FSTHICK file for free-size optimization contained incorrect nodal thicknesses. This has now been fixed.
  • When one of the parts connected by FREEZE, CONTACT is removed using MODCHG (with PARAM,MCHGRMV,1) but the associated contact definition is not removed, the run previously failed with ERROR 4772. This has now been fixed.
  • Incorrect Displacement and Stress results were generated for elements which are close to rigid elements for SMDISP Inertia Relief models. This has now been fixed.
  • OptiStruct-Flux Optimization with both EM and Mechanical responses previously required a large amount of memory. This has now been fixed.
  • Parameter Optimization with load design variable and SPCFORCE moment response previously did not show a progression in the optimization, and soft converged in a single iteration. This has now been fixed.
  • Coincident RBE2s led to double-dependency error even if the second RBE2 was excluded using MODCHG. This has now been fixed.
  • When multiple MATMDS with different number of constituent materials (for example, are associated with a Laminate), unpredictable results were observed. This has now been fixed.
  • Incorrect results were generated when TLOAD2 entries were referenced by DLOAD in an Implicit Nonlinear analysis. This has now been fixed.
  • A model with nonlinear heat transfer analysis with higher number of SMP threads previously led to a memory insufficient error. This has now been fixed.
  • For OSTTS optimization, when the initial temperature for the transient heat transfer subcase is zero, previously the run failed with an error that all sensitivities for the objective are zero. This has now been fixed.
  • An incorrect ERROR was generated when TEMP(LOAD) in a Nonlinear Transient subcase with CNTNLSUB was pointing to a different temperature load set from the TEMP(INITIAL). This has now been fixed.
  • For electrical optimization with non-electrical responses (such as volume, mass, and so on) without any structural material present, previously the model failed with a programming error. This has now been fixed and a clear error is now issued which mentions that a valid structural material is required for structural responses.