What's New

View new features for OptiStruct 2022.3.

Altair OptiStruct 2022.3 Release Notes

Highlights

Two-dimensional Plane Stress Elements
New fastener elements with CFASTG
Heat flux and Current output at model cross-sections
Thickness gradient constraints for Free-size Optimization

New Features

Stiffness, Strength and Stability

Parameters for debugging of Nonlinear Analysis

There is a new set of parameters introduced, known as NLDEBUG parameters which helps with debugging of nonlinear analysis by simplifying certain aspects of the model. The following parameters are now available:

NLDEBUG,RMNLMAT: Setting this parameter will ignore nonlinear materials specified in the model. Typically, certain nonlinear materials are completely ignored while other nonlinear materials are linearized.
NLDEBUG,NLP2NLC: Setting this parameter will convert NLPARM-based setup to an NLCTRL-based setup in a nonlinear model. When NLPARM (and additionally NLADAPT, if any) entries are defined in nonlinear models, then they are converted internally to NLCTRL.
NLDEBUG,CONT2TIE: Setting this parameter in a model which contains contact will convert any non-FREEZE contact internally to FREEZE contact.; Refer to the OptiStruct 2022.3 documentation for more details on NLDEBUG parameters.

Plane Stress

The two-dimensional plane stress elements are now available. The quadrilateral and triangular plane stress elements are CQPSTS and CTPSTS, respectively (both are applicable to first order and second order elements). Plane stress elements reference PPLANE as property and all elements should be defined either in x-y plane or in x-z plane. Plane stress elements can be used for linear static analysis, nonlinear static analysis with both SMDISP and LGDISP options, transient and frequency response analysis, real and complex eigenvalue analysis. Currently they do not support inertia relief analysis, buckling analysis, heat transfer analysis and optimization. The currently supported materials are MAT1, MATS1 and MAT2.

Ductile Damage

Ductile damage initiation based on plastic strain has been added. This is supported for solids in both small displacement and large displacement nonlinear analysis. It is also supported for shells, for small displacement nonlinear analysis only. DAMAGE continuation line has now been added in MATS1 entry (elasto-plasticity). DAMAGE continuation line refers to DMGINI (damage initiation) and DMGEVO (damage evolution) Bulk Data Entries.

New JOINTG output requests

Two new JOINTG output requests are now available:

JOINTD I/O Entry is available for JOINTG displacement output.
JOINTF I/O Entry is available for the following JOINTG output:
- JOINTG Forces
- JOINTG Reaction Forces
- JOINTG Viscous Forces (available if PROPERTY on PJOINTG is DAMP)
- JOINTG Stop and Lock Status

JOINTF is turned on by default for linear/nonlinear static analysis and explicit analysis.

JOINTD is not currently the default for any analysis type.

JOINTD and JOINTF output are available in .h3d, _impl.h3d, _expl.h3d, and .joint files.

"SLIP history" contact output

The CONTF(SLIPPED,OPTI) option can be used to activate output of whether a frictional contact interface has experienced slipping status up to the current increment in an implicit nonlinear analysis.

Change in PARAM,KSMNL4PL Default

The default of PARAM,KSMNL4PL has been changed from 0 to 1.

Adiabatic Analysis

Adiabatic analysis is now available in OptiStruct. It is a coupled thermal-structural analysis, which is applicable in modeling systems with inelastic strain which can lead to quick heating of the material, without sufficient time for the heat to be transmitted. The heat transfer and structure analysis are coupled at each time step.

An ADIABATIC Subcase Entry should be specified in an implicit nonlinear subcase to activate adiabatic analysis.
It is currently supported for both Nonlinear static and Nonlinear transient analysis (SMDISP and LGDISP)
Three-dimensional elements and Axisymmetric elements are currently supported.
Some parts of the model are made of elastic material, and other parts are inelastic.
Elasto-plasticity (MATS1), Visco-elasticity (MATVE), Cohesive elements (MCOHE, MCOHED) are supported for defining inelastic materials for adiabatic analysis.
Cohesive elements only work as a heat source. Heat conduction or specific heat effect are not considered for cohesive elements.
All the elements in a model participate in the structural analysis, but only the elements with thermal material participate in thermal analysis.
Results for adiabatic analysis are available, such as Grid temperature, Temperature gradient, Heat flux, Element heat energy, incremental heat power density, total heat power density, and so on.

Explicit Dynamic Analysis

JOINTG results in time history output (THIST): The results include JOINTG force, reaction force, viscous force and STOP/LOCK status in time-history output for explicit analysis.
Cohesive Elements: The constitutive response of cohesive elements using a traction-separation description by using MCOHED (in order to define the damage initiation and damage evolution), or define the constitutive response of cohesive elements using a continuum approach by referencing isotropic material (MAT1) or elasto-plasticity material (MATS1). This is now supported for explicit analysis.
Nodal mass change output: Nodal mass change due to mass scaling is available in .h3d file. This is the delta mass (identifies how much mass is added).
New failure type in MATF as maximum plastic strain: A New failure type is now available in MATF, which can be activated by setting CRITERIA field to PLAS. This activates the maximum plastic strain failure criterion. The V1 field on MATF defines the maximum plastic strain value for the failure calculation.

Electrical Analysis

Pressure and clearance dependent resistivity in PCONTEC

Pressure and Clearance-dependent resistivity can now be defined on PCONTEC entry for electrical analysis. The TPID field is available to point to a TABLED# entry that specifies resistance per unit contact area, based on contact pressure. The TCID field points to a TABLED# entry that specifies resistance per unit contact area, based on contact clearance. TPID can be specified together with TCID.

Refer to the PCONTEC documentation for more information.

Sequential coupling of structural, electrical analysis, and heat transfer analysis

Structural, electrical, and heat transfer analyses can now be sequentially coupled in OptiStruct. The following subcases are currently supported for this implementation:

Structural analysis

Implicit Nonlinear Static Large Displacement Analysis

Heat Transfer analysis

Linear or Nonlinear Steady-State Heat Transfer
Linear Transient Heat Transfer

Electrical analysis

Steady-State Electrical analysis
Multi-Steady Electrical analysis

All three analyses are defined in the model. The structural analysis subcase should be referenced by both the electrical and heat transfer subcases via STATSUB(STRUCTURE). The heat transfer subcase should reference the electrical analysis subcase via the JOULE entry. The solution coupling process depends on the type of defined subcases, but generally, the structural analysis will be solved first. There will be no influence of heat transfer and electrical subcases on the structural subcase. The deformed mesh from the structural subcase, sequentially is used to update the conduction or convection characteristics of heat transfer (electrical or heat subcase), and the corresponding loading, such as QVOL or QBDY1, and subsequently contact (which also influences TPID and TCID in PCONTEC).

Current flow output across sections

Current flow output across sections of the model is now available via the RESULTANT I/O Entry. The sections in the model for which output is requested should be defined via the SECTION Bulk Data Entry, with the STYPE field set to ELEC. The presence of SECTION entry is sufficient for Current flow output in Steady-State Electrical analysis (RESULTANT is default). For Multi-Steady Electrical Analysis, both SECTION entry and the RESULTANT entry are required for Current flow output. Current flow results are output in H3D and .secres files.

Noise and Vibration

Performance enhancement of MATFi materials: The performance of frequency-dependent materials (MATFi) has been enhanced. Especially enhancements that have been applied in identifying material data where properties do not change over certain loading frequencies.
Steady-state analysis for Vibration solutions: Steady-state analysis is now available for Vibration solutions to convert results of frequency-response analysis from frequency domain to time domain and also optionally combine the results with results from static subcases and other frequency-response subcases in the time domain. Currently, displacement, velocity, acceleration, stress and strain are supported.; A new subcase type, ANALYSIS STEADY is now available for Steady-state analysis. The STEADY Subcase Information Entry is available and should point to the new STEADY Bulk Data Entry, to activate steady-state analysis. The STEADY Bulk Data Entry provides options to control the combination of frequency response and linear static subcases used for steady-state analysis.; The IMPORT I/O Entry can be used in the corresponding FRF and linear static subcases to run steady-state analysis directly from H3D files. All corresponding subcases should contain the IMPORT I/O Entry in such a situation.

Rotor Dynamics

Order-based FRF analysis for rotor dynamics

The SYNCFAC field is now available on the RGYRO Bulk Data Entry to specify the scaling factor used for rotating speed in order-based frequency response analysis for rotor dynamics. This scaling factor is applied to the rotating speed of the reference rotor to determine the rotating speed of a rotor.(1)

ω = S Y N C F A C \cdot Ω_{r e f}

Where,

$ω$: Whirling frequency (Hz).
$Ω_{r e f}$: Speed of the reference motor (Hz).

Fatigue Analysis

Superimpose stress from transient analyses with stress from static subcases

A single FATEVNT entry can now combine the transient analysis results and the static subcase results via FATLOAD with user-defined scaling factor.

See an example below. FATLOAD 611 and

FATLOAD
                                612

reference static subcases while

FATLOAD
                                601

and FATLOAD 44 reference transient subcases.

FATSEQ       401
+            501       1     911       2
FATEVNT      501     601     611      44     612
FATEVNT      911     611      44
FATLOAD      601              11   
FATLOAD       44              15   
FATLOAD      611             109   0.5      
FATLOAD      612             119   0.500

Heat Transfer Analysis

Heat Flow output across sections: Heat flow output across sections of the model is now available via the RESULTANT I/O Entry. The sections in the model for which output is requested should be defined via the SECTION Bulk Data Entry, with the STYPE field set to HEAT. The presence of SECTION entry is sufficient for Heat flow output in Linear and Nonlinear Steady-State Heat Transfer analysis (RESULTANT is default). For Linear and Nonlinear Transient Heat Transfer Analysis, both SECTION entry and the RESULTANT entry are required for Heat flow output. Heat flow results are output in H3D and .secres files.

Optimization

LEVELSET optimization requires reduced number of iterations: LEVELSET optimization has been enhanced to require a reduced number of iterations to converge, while simultaneously maintaining solution robustness and accuracy.
Thickness gradient with Free-size optimization: Thickness gradient constraints are now available with free-size optimization. This can be defined via the DRAW continuation line on the DSIZE Bulk Data Entry. Two options are available for defining the draft angle type: FIXED and MINIMUM. The FIXED option fixes the draft angle, while the MINIMUM option activates the variable draft angle option. The Thickness gradient direction is defined via the DAID and DFID fields, and the draft angle is defined via the ANGLE field.
Element SET based design space for topology and free-size optimization: The design space for Topology and Free-size optimization can now be defined via element SETs. This is defined by setting the PTYPE field on DSIZE or DTPL entries to SET. Then the PID# fields can reference the corresponding element SET IDs. Depending on whether DTPL or DSIZE is used, the element SET can be a set of solid or shell elements. Multi-material, levelset, and lattice optimization are currently not supported.; Refer to the DTPL and DSIZE documentation for more information.

General

Power flow output for Transient Analysis: Power flow output, via the POWERFLOW I/O Entry, is now supported for Direct and Modal Transient Response Analysis. It was already supported for Direct and Modal Frequency Response Analysis in previous releases.
SET of grids support for ASET/BSET/CSET, BNDFIX/BNDFIX1 and BNDFREE/BNDFREE1: The grids to be defined as part of the entries ASET/BSET/CSET, BNDFIX/BNDFIX1 and BNDFREE/BNDFREE1, can now also be defined as grid SETs. This is available by setting the GSET flag on the corresponding entry, leading to the IDs being considered as grid SETs instead of individual grids.
MASSSET: MASSSET can be used to define subcase-dependent mass using the MASSSET Subcase Information and MASSSET Bulk Data Entries. The masses can be defined as mass sections via the BEGIN,MASSID entries. These sections have their own IDs and these IDs can be referenced (for scaling and linear combination) on the MASSSET Bulk Data Entry. The MASSSET Bulk Data Entry is then referenced in a subcase by the MASSSET Subcase Information Entry.
SHIFTY for TLOAD2: The load amplitude (Y) on the TLOAD2 entry can be shifted using the SHIFTY field on the TLOAD2 Bulk Data Entry. A real value should be specified on the SHIFTY field to apply a shift to the load amplitude. This is currently supported for direct and modal linear transient analysis.

Resolved Issues

The results in HyperView no longer show NA when the corner option is turned on for factor of safety output with 2nd order elements.
You can no longer apply zero loading may be applied when the cylindrical system is used for gravity loading.
Topology optimization results have been corrected for transient analysis with material damping.
NODMIG option now works as expected for GROUNDCHECK.
Odd results with Level set optimization are no longer observed when the draw direction constraints are used.
Corrected the insufficient memory available issue for Simpack recovery run.
Acceleration loading (ACCEL,ACCEL1,ACCEL2) defined in local part is now handled as expected when used in parts-instances with the ROTATE option.
A programing error no longer occurs when ERP participation is requested and there are fluid elements in the model.
A high enough stiffness is used for rotational dofs with penalty-based RIGID option in PBUSH to resolve issues with low stiffness.
Contribution from contact in GPFORCE are corrected so they are no longer constant for each time increment in nonlinear analysis.
Homogenized shell stress for composite models in large displacement nonlinear analysis.
Gravity loading with cylindrical coordinate system defined no longer produces zero force.
Kinetic frictional force output is now correct for continuous sliding contact (CONSLI).
MPC force in .op2 file from large displacement nonlinear analysis is now correct.

Altair OptiStruct 2022.2 Release Notes

Highlights

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
3D elements: CHEXA, CPENTA, CTETRA, CPYRA

Optimization

Symmetry constraints for 1D topology: Pattern grouping for topology is now additionally supported for PBAR, PBARL, PBEAM, PBEAML, and PROD properties.

General

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.

Altair OptiStruct 2022.1 Release Notes

Highlights

Piezoelectricity
New Nonlinear Convergence Criteria Control (NLCTRL)
New Creep Material (Anand, Darveaux)
Deformation Gradient Tensor
Axisymmetric Elements for Heat Transfer
APML (Adaptive Perfectly Match Layer) for Exterior Acoustics

New Features

Stiffness, Strength and Stability

New Nonlinear Convergence Criteria Control, NLCTRL

Newly added Bulk/Subcase Entry, NLCTRL, supports different convergence criteria than existing nonlinear convergence criteria in NLPARM Bulk Data Entry. The criteria are based on the displacement and the residual force. NLPARM will continue to be supported and can be used in Nonlinear Analysis. NLCTRL Bulk Data Entry supports existing convergence criteria on NLPARM, and in addition, also supports all the existing options available in NLADAPT. Therefore, there is no need to use both NLCTRL and NLADAPT or NLCTRL and NLPARM at the same time. An error message will appear if NLCTRL and NLADAPT or NLCTRL and NLPARM are used in the same subcase.

Shell to Solid connection with RSSCON1

RSSCON1 is a more user friendly definition of shell to solid connection than existing RSSCON, where the solids and shells that need to be connected are defined through the SURF Bulk Data Entry with RSSCON1. It also allows the connection in case the multiple layers of solids need to be included in kinematic condition because the thickness of shell is large and also RSSCON1 is supported for large displacement nonlinear analysis while RSSCON is not.

New Creep Material, Anand and Darveaux

Anand and Darveaux creep material are available as new creep material type in MATVP.

Deformation Gradient Tensor in User Material, MATUSR

Deformation Gradient Tensor is supported for user material MATUSR as arguments in the user material subroutine. The dfgrold and dfgrnew arguments are now available to define the deformation gradient tensor of the previous increment and the deformation gradient tensor of the current increment.

Utilization factor output

UTIL option in CONTF contact force output will trigger the output of utilization factor and shear magnitude.

Shear magnitude is the summation of grid shear force. Utilization factor is given by:(2)

U = [\frac{\frac{\sum G r i d s h e a r f o r c e}{F r i c t i o n C o e f f i c i e n t}}{\sum G r i d n o r m a l F o r c e}] = \frac{\frac{S h e a r m a g n i t u d e}{μ}}{\sum F_{n}}

Utilization factor (U) is a quantitative measure for determining the load increment at which sliding has occurred (if any). When the utilization factor gets closer to one, sliding occurs.

Currently supported output formats are:

Result Type: Comments
Shear utilization factor: It is available only in H3D and OPTI formats.; In H3D format, it is output on each node.; In OPTI format, it is output for each contact interface.
Shear magnitude: It is output for each contact interface and is available only in OPTI format.

Contact pressure dependent Contact Status in preloaded analysis

CNTLCK Bulk Data Entry is now available and used to specify the contact pressure threshold. If the contact pressure from the nonlinear analysis is larger than the threshold defined in CNTLCK, the contact is assumed to be closed in subsequent preloaded linear analysis (such as preloaded Modal Frequency Response). This CNTLCK Bulk Data Entry should be referenced by CNTLCK Subcase Information Entry in the preloading Nonlinear Static Analysis subcase (small and large displacement analysis are supported). The contact lock is then applied to the preloaded Linear Analysis subcase, which is preloaded by the corresponding Nonlinear Static Analysis subcase that contains the CNTLCK Subcase Information Entry.

User-defined State variables label for MATUSR/MATUSHT

Subroutine initusr can be called from MATUSR/MATUSHT user subroutines to define user-defined label for state variables.

Shell elements can be defined in the pretension bolt

Shell elements are now supported in pretension bolt. The Error message has been removed, even if shells (typically membrane) are defined in the bolt defined with PRETENS.

Contact Friendly elements (CONTFEL) activated automatically for N2S and second order solids

Contact Friendly elements (CONTFEL) will be activated automatically for N2S and second order solids in model, even if the DISCRET field is blank on the CONTACT/TIE entries.

Kinematic and Mixed hardening plasticity for shells

Kinematic and mixed hardening for elasto-plasticity material is now supported for 1^st order shells in small displacement nonlinear static/transient analysis.

Second order shells support for MODCHG

Second order shells support for MODCHG.

Moment output support for Contact

Moment output is available for Contact with CONTF output request in .cntf file. Moment output is only available when the continuation line MNTREF in CONTACT Bulk Data Entry is defined.

The reference point of moment calculation can be specified several ways, such as the user-defined grid ID, the center of contact, the origin of the model and the user-defined coordinates (x,y,z).

Nonlinear Restart enhancement

Nonlinear Restart supports Moment Bulk Data Entry and fluid elements.

Explicit Dynamic Analysis

JOINTG for elastic bodies instead of only on rigid bodies: JOINTG is now allowed to be defined on elastic bodies.
CBUSH without mass is supported: CBUSH now works without any user-defined mass in PBUSH.

Heat Transfer Analysis

Axisymmetric elements for Heat Transfer Analysis: Axisymmetric elements are now supported for any Heat Transfer Analysis. Thermal contact (both node-to-surface and surface-to-surface) is also supported for heat transfer analysis with axisymmetric elements.
STATSUB(STRUCTURE) for Transient Heat Transfer: STATSUB(STRUCTURE) can be used to carry over the CONTACT/GAP status from the preceding nonlinear analysis. STATSUB(STRUCTURE) is now supported for any heat transfer subcase.
Composite (PCOMP, PCOMG, PCOMPP/STACK) support for Heat Transfer: Composite properties are supported for Heat Transfer Analysis.
Power output with SPCF for convection ambient point in Steady-State and Transient Heat Transfer Analysis: Power output for convection ambient point is available with SPCF output request.

Noise and Vibration

APML (Adaptive Perfectly Matched Layer) for Exterior Acoustics

A new exterior acoustics solution, Adaptive Perfectly Matched Layer (APML) is now available. It is an extensively used solution in the exterior acoustics field. APML enables excellent improvement in performance efficiency (compared to Infinite Elements), while maintaining accuracy, by leveraging the technique of frequency band generation in conjunction with automatic adaptive mesh generation for each frequency band. A lightweight SimLab mesher is embedded with the OptiStruct installation, allowing for seamless adaptive meshing dynamically in real time. The acoustic pole coordinates are also internally calculated by APML (in contrast to IE).

The APML setup is straightforward (and similar to IE), wherein you need the following data:

Create an acoustic cavity mesh which fully encloses the vibrating structure of interest.
Create a boundary PML mesh layer using CACPML3/4 elements at the outer surface of the acoustic cavity mesh.
The PACPML property entry is associated with the CACPML3/4 elements to define the APML properties.
Frequency-band generation is active by default using the ADAPF method, but additional control is available via the PACPML entry, or the frequency bands can be defined directly using the MESHF entry.
The microphone grid points can be defined for acoustic output requests (similar to IE).
The sound pressure (DISP) output is currently supported for APML.
The lightweight SimLab mesher is used to internally generate the various adaptive meshes without requiring any additional user input.

Automatic adjustment of Normal direction of panels for ERP

The normal direction of elements in panels will automatically be flipped in case they are not consistent across the panels used for ERP. This is required for ERP output.

Area output for PANEL used in ERP and the automatic output of sum of all ERP PANEL contributions

For ERP application, the following output is now available automatically in punch file:

Area output for each panel
Total ERP from all panels

Unconnected parts output with AMSES

PARAM,CHKUCON is available to output unconnected parts during an AMSES run.

JOINTG force output in h3d file for Frequency Response and Random Response

JOINTG force in Frequency Response and Random response (PSD/RMS) are available in h3d file when the STRESS output entry is specified.

Subcase-dependent RESVEC’s for multiple Modal Frequency Response and Transient Response

With multiple dynamic response subcases, the union of RESVEC (residual vectors) from all subcases are used for all the subcases, which is the default behavior. If PARAM,SUBRESVC,YES is used, the residual vectors generated from a particular subcase will be used for that subcase only, instead of using the union of residual vectors from all the subcases.

PARAM,FCACSV,YES

Fluid-structure complex eigenvalue analysis runs previously generated a *.cmode.csv by default, which contains mass fraction, MAC, and so on. This file is now only available when PARAM,FCACSV,YES is defined in input file.

Fatigue

Multi Haigh with constant R ratio: For damage evaluation using multiple Haigh diagram in MATFAT, a new interpolation method is added, which is based on constant R ratio in addition to the existing interpolation method of constant mean stress.
Multi-SN curve support for Multi-Axial SN fatigue and Random, Sine Sweep Fatigue: Multi-SN curve is supported for Muti-Axial SN fatigue and Dynamic Fatigue such as Random and Sine Sweep fatigue.

Optimization

Error messages in Multi-Model Optimization (MMO) printed in the main process: Any error messages that occur in secondary processes are now also printed in the main process for MMO.

General

Piezoelectricity: Piezoelectric materials are a class of materials in which structural deformation triggers electrical potential and vice versa. OptiStruct supports two-way Piezoelectric coupling in which a mechanical excitation will generate an electrical response. Conversely, an electrical excitation will generate a mechanical response. The coupling is strong, which means that both mechanical and electrical responses are solved simultaneously.
TEMPADD: Multiple TEMP Bulk Data Entries can be combined by using the newly introduced TEMPADD Bulk Data Entry. The TEMPADD Bulk Data Entry can be referenced anywhere the TEMP or TEMPD Bulk Data Entry can be referenced.
Electrical Conduction Analysis results: For the Multi-Steady Electrical Conduction Analysis coupled with heat transfer analysis, the electrical conduction results are available in its own subcase, instead of being included in heat transfer analysis subcase results.
Disk space reduction for AVL EXCITE interface jobs: AVL EXCITE interface jobs with PARAM,EXCEXB now requires the minimum amount of disk space needed to complete the job.
Make the corner stress default with OptiStruct.cfg file: OutStress option in the OptiStruct.cfg file allows the specification of selected default location options for stress output. Locations now supported for the new OutStress option in the configuration file are CORNER, BILIN, CUBIC and SGAGE.
Disable the output of automatic bolt force output in .secres file: NOBOLT option in RESULTANT output request will disable the automatic bolt force output in the .secres file. That is RESULTANT(NOBOLT) = ALL.
MIRROR option in DMIGMOD: DMIGMOD RELOC option now has the MIRROR option, which can be used to mirror the superelement.
GRID SET support for Initial Condition (TIC): GRID SET is supported for Initial Condition Bulk Data Entry, TIC for both implicit and explicit analysis. If the GSET flag is specified, the corresponding ID specified on the GID/GSETID field identifies a GRID SET.
Temperature loading support for Linear Transient Analysis: Temperature loading is supported for Linear Transient Analysis with TLOADi Bulk Data Entry. The TEMP/TEMPD/TEMPADD Bulk Data Entries can be referenced on the TLOADi Bulk Data Entry, which can then be referenced on the DLOAD Subcase Information Entry in a Linear Transient subcase.
JOINTG contribution in Grid point force (GPFORCE) in h3d, punch and gpf file: JOINTG contribution is included in GPFORCE output and labeled as RJOINT.
Compliance calculation with temperature loading: The accuracy of compliance calculation with temperature loading has been improved.

Enhancements

Accessing Tutorial Model Files: You can now click a link, within a tutorial, to download the required model file(s) for that tutorial.
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.

Resolved Issues

Thermal material user subroutine (MATUSHT) no longer produce incorrect results, if HGEN is provided as PROPERTY to MATUSHT.
The following issues are fixed for Component-based Effective Mass output through MEFFMASS.
- The results could be incorrect unless the strain energy or kinetic energy is requested.
- Modal participation ratio in .mvw file could be incorrect.
PFPANEL results are correct, if PARAM,ASCOUP,NO is used and also AMSES/AMLS is used as eigenvalue solver with a reduced output set.
RMS SPCF in Random analysis could be zero, unless SPCF is also requested for FRF subcase. This has been fixed.
PFMODE model no longer encounters a programming error, if there are many subcases and the number of grids in GRIDC is large.
Adjust option in CONTACT works properly for large displacement nonlinear analysis.
Programming error no longer occurs with Hyperelastic material (MATHE) and MODCHG.
Explicit dynamic analysis results are correct, if certain subcases have initial conditions and other subcases do not.
RMS/PSD Corner stress for solid elements.
The job completes, if PHASE option is specified with SPCD in Frequency Response Analysis.
Nonlinear Restart job with RESTARTR no longer fails.
Modal Frequency Response job completes when energy output is requested.
Automatic conductivity calculation with KCHTC=AUTO has been improved, even if the material has temperature-dependent material with MATT4.
Normal modes analysis with GPU job produce correct results.
Electrical material input for PCOMP(G)/PCOMPP was treated internally as resistivity instead of conductivity and this has been fixed.
Contact element contribution for moment in grid point force balance table is no longer missing.
Current density for solid element in multi-step electrical analysis is applied properly.

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 you 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: 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).
Clearance is assumed to be 0.0 for FREEZE/TIE Thermal Contact: 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 you 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.