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Reference Guide
This manual provides a detailed list and usage information regarding input entries, output entries, and parameters available in OptiStruct.
Input Data
I/O Options Section
Alphabetical listing of the I/O Options Entries.
HYBDAMP
I/O Options and Subcase Information Entry The HYBDAMP command can be used in the I/O Options section to request modal damping as a function of the natural frequency of the model in Dynamic Analysis.

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OptiStruct is a proven, modern structural solver with comprehensive, accurate and scalable solutions for linear and nonlinear analyses across statics and dynamics, vibrations, acoustics, fatigue, heat transfer, and multiphysics disciplines.
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User Guide
This manual provides detailed information regarding the features, functionality, and simulation methods available in OptiStruct.
Reference Guide
This manual provides a detailed list and usage information regarding input entries, output entries, and parameters available in OptiStruct.
- Input Data
  - Bulk Data Input File
    The input file in OptiStruct is composed of three distinct sections.
  - I/O Options and Subcase Information Entries Guidelines
    The following guidelines apply to all entries in the I/O Options and Subcase Information sections.
  - Bulk Data Guidelines
    The following guidelines apply to all entries in the Bulk Data Entry section.
  - Solution Sequences - Data Selectors
    The Data Selectors table is available in an Excel spreadsheet.
  - Supported Optimization Type Chart
    Supported types of optimization for various analysis sequences are outlined.
  - I/O Options Defaults Summary
  - I/O Options by Function
    Descriptions for individual I/O Option Entries can be accessed by selecting from the links for each entry, listed below in groups according to their purpose and alphabetically on the I/O Options section page.
  - Subcase Information Entries by Function
    Descriptions for individual Subcase Information Entries can be accessed by selecting from the links for each entry, listed below in groups according to their purpose and alphabetically on the Subcase Information Section page.
  - Bulk Data Entries by Function
    Guidelines for using Bulk Data Entries are listed in Bulk Data Guidelines.
  - I/O Options Section
    Alphabetical listing of the I/O Options Entries.
    - @HYPERFORM
      I/O Options and Subcase Information Entry The @HyperForm statement indicates an input file for one-step stamping simulation written from HyperForm.
    - ACCELERATION
      I/O Options and Subcase Information Entry The ACCELERATION command can be used in the I/O Options or Subcase Information sections to request acceleration vector output for all subcases or individual subcases, respectively.
    - ACDISP
      I/O Options and Subcase Information Entry Used in the I/O Options section or in Acoustic Complex Eigenvalue Analysis Subcases to request displacement for acoustic grids. This output request is only supported for acoustic interface grids.
    - ACINT
      I/O Options and Subcase Information Entry Used in the I/O Options section or in frequency response (direct and modal) subcases to request acoustic intensity at the fluid grids.
    - ACPOWER
      I/O Options and Subcase Information Entry Used in the I/O Options section or in frequency response (direct and modal) subcases to request acoustic power radiated across a panel for Infinite Elements and Adaptive Perfectly Matched Layer (APML).
    - ACPVELO
      I/O Options and Subcase Information Entry Used in the I/O Options section or in frequency response (direct and modal) subcases to request particle velocity at the fluid grids.
    - AEROF
      I/O Options and Subcase Information Entry Used to request aerodynamic loads on aerodynamic control points.
    - APRESSURE
      I/O Options and Subcase Information Entry Used to request aerodynamic pressures in static aeroelastic response.
    - ASSEMBLY
      I/O Options EntryDefines an assembly of parts which are included in the global model.
    - ASSIGN
      I/O Options and Subcase Information Entry Identifies external files and their contents.
    - AUTOSPC
      I/O Options and Subcase Information Entry The AUTOSPC command can be used to automatically constrain stiffness singularities and near singularities with single point constraints.
    - CDSMETH
      I/O Options and Subcase Information Entry The CDSMETH command can be used in component dynamic synthesis method for generating component dynamic matrices at each loading frequency.
    - CFAILURE
      I/O Options and Subcase Information Entry The CFAILURE command can be used in the I/O Options or Subcase Information sections to request failure index output for shell elements referencing PCOMP, PCOMPP or PCOMPG properties for all subcases or individual subcases, respectively.
    - CHECK
      I/O Options and Subcase Information Entry The CHECK command can be used in the I/O Options section to request that only a model check be performed.
    - CMDE
      I/O Options and Subcase Information Entry The CMDE command can be used above the first SUBCASE or within a SUBCASE definition to request component modal synthesis damping energy output for all subcases or individual subcases, respectively.
    - CMKE
      I/O Options and Subcase Information Entry The CMKE command can be used above the first SUBCASE or within a SUBCASE definition to request component modal synthesis kinetic energy output for all subcases or individual subcases, respectively.
    - CMSE
      I/O Options and Subcase Information Entry The CMSE command can be used above the first SUBCASE or within a SUBCASE definition to request component modal synthesis strain energy output for all subcases or individual subcases, respectively.
    - CONTF
      I/O Options and Subcase Information Entry The CONTF entry can be used to request contact results output for all subcases or individual linear static, nonlinear analysis, linear inertia relief and explicit dynamic analysis subcases.
    - CSTRAIN
      I/O Options and Subcase Information Entry Used in the I/O Options or Subcase Information sections to request ply strain output for shell elements referencing PCOMP, PCOMPP or PCOMPG properties for all subcases or individual subcases, respectively.
    - CSTRESS
      I/O Options and Subcase Information Entry Used in the I/O Options or Subcase Information sections to request ply stress output for shell elements referencing PCOMP, PCOMPP or PCOMPG properties for all subcases or individual subcases, respectively.
    - CURRDEN
      I/O Options and Subcase Information Entry Used to output current density results in electrical analysis.
    - DAMAGE
      I/O Options and Subcase Information Entry Used to request fatigue damage results output for all fatigue subcases or individual fatigue subcases, respectively. Also supported in Damage initiation output for OSTTS analysis.
    - DEBUG
      I/O Options and Subcase Information Entry The DEBUG entry is used by Altair HyperWorks Support for internal issue debugging purposes.
    - DENSITY
      I/O Options and Subcase Information Entry The DENSITY command can be used in the I/O Options section to request density output for a topology optimization.
    - DESGLB
      I/O Options and Subcase Information Entry The DESGLB command can be used in the I/O Options section, before the first subcase statement, to select a constraint set that is not subcase dependent.
    - DESHIS
      I/O Options and Subcase Information Entry The DESHIS command can be used in the I/O Options section to control the creation of the optimization history file .hgdata.
    - DGLOBAL
      I/O Options and Subcase Information Entry The DGLOBAL command can be used in the I/O Options section to activate the Global Search Option (GSO).
    - DISPLACEMENT
      I/O Options and Subcase Information Entry Used to request displacement vector output for all subcases or individual subcases, respectively.
    - DMIGNAME
      I/O Options and Subcase Information Entry The DMIGNAME command can be used in the I/O Options section to define the name given to the reduced matrices written to an external data file.
    - DRESPONSE
      I/O Options and Subcase Information Entry The DRESPONSE command can be used in the I/O Options section to request Design Response Output for optimization runs. The DRESP1, DRESP2, and DRESP3 responses in the model are output as contours in the H3D file.
    - DSA
      I/O Options and Subcase Information Entry The DSA command can be used in the I/O Options section to request Design Sensitivity Analysis results in a Frequency Response Analysis.
    - ECHO / ECHOON / ECHOOFF
      I/O Options and Subcase Information Entry The ECHO command can be used in the I/O Options section causing the output of the interpreted forms of Subcase Information and Bulk Data Entries to the .out file. The ECHOON command can be used in the I/O Options, Subcase Information, or Bulk Data sections causing the (verbatim) output of any subsequent I/O Options, Subcase Information, or Bulk Data Entries to the .out file until an ECHOOFF command is encountered. The ECHOOFF command can be used in the I/O Options, Subcase Information, or Bulk Data sections suppressing the output of any subsequent I/O Options, Subcase Information, or Bulk Data Entries to the .out file until and ECHOON command is encountered.
    - EDE
      I/O Options and Subcase Information Entry Used to request element energy loss per cycle and element energy loss per cycle density output for all subcases or individual subcases, respectively.
    - EIGVNAME
      I/O Options and Subcase Information Entry Used to define the prefix to be used for external eigenvalue data files (.eigv).
    - EKE
      I/O Options and Subcase Information Entry The EKE command can be used in the I/O Options or Subcase Information sections to request kinetic energy and kinetic energy density output for all subcases or individual subcases, respectively.
    - ELECFIELD
      I/O Options and Subcase Information Entry Used to output electric field results in electrical analysis.
    - ELECMAT
      I/O Options and Subcase Information Entry Used to output conductivity and resistivity results in electrical analysis.
    - ENDLOAD
      I/O Options and Subcase Information Entry The ENDLOAD command can be used in the I/O Options or Subcase Information sections to request End Load output for all edges for relevant subcases or individual subcases, respectively.
    - EQSTSAMP
      I/O Options and Subcase Information Entry Used to request Equivalent Stress results for all fatigue subcases or individual fatigue subcases, respectively.
    - ERP
      I/O Options and Subcase Information Entry Used to request equivalent radiated power output for all subcases or individual subcases, respectively.
    - ESE
      I/O Options and Subcase Information Entry Used to request strain energy and strain energy density output for all subcases or individual subcases, respectively.
    - FAILURE
      I/O Options and Subcase Information Entry Used to request failure output for elements referencing PSOLID or PSHELL properties for all subcases or individual subcases, respectively.
    - FLUX
      I/O Options and Subcase Information Entry Used to request temperature gradient and flux output for all steady-state heat transfer analysis subcases, transient heat transfer analysis subcases or individual heat transfer analysis subcases, respectively.
    - FORCE / ELFORCE
      I/O Options and Subcase Information Entry Used to request structural element force output and elemental fluid particle velocity output for all subcases or individual subcases, respectively.
    - FORMAT
      I/O Options EntryThe FORMAT command can be used in the I/O Options section to indicate the format in which results are to be output.
    - FOS
      I/O Options and Subcase Information Entry Used to request fatigue factor of safety, hydrostatic pressure, and shear stress output for all fatigue subcases or individual fatigue subcases. It also controls the output of Safety Factor (SF) from SN Fatigue Analysis.
    - GPCURRENT
      I/O Options and Subcase Information Entry Used to output grid point current results in electrical analysis.
    - GPFORCE
      I/O Options and Subcase Information Entry Used to request grid point force balance output for all subcases or individual subcases, respectively.
    - GPKE
      I/O Options and Subcase Information Entry The GPKE command can be used in the I/O Options or Subcase Information sections to request grid point kinetic energy output for normal modes subcases.
    - GPSTRAIN
      I/O Options and Subcase Information Entry Can be used to request grid point strain output for all or individual subcases, respectively.
    - GPSTRESS / GSTRESS
      I/O Options and Subcase Information Entry The GPSTRESS command can be used in the I/O Options or Subcase Information sections to request grid point stresses output for all subcases or individual subcases, respectively.
    - HARMONICS
      I/O Options EntryUsed to specify the solution harmonics to be used in cyclic symmetry analysis.
    - HEAT
      I/O Options and Subcase Information Entry Used to output Joule loss density results in electrical analysis.
    - HISOUT
      I/O Options and Subcase Information Entry The HISOUT command can be used in the I/O Options section to control the amount of data printed to the .hgdata file.
    - HYBDAMP
      I/O Options and Subcase Information Entry The HYBDAMP command can be used in the I/O Options section to request modal damping as a function of the natural frequency of the model in Dynamic Analysis.
    - IMPORT
      I/O Options and Subcase Information Entry Identifies H3D files.
    - INCLUDE
      I/O Options and Bulk Data Entry and Subcase Information Entry The INCLUDE command can be used in the I/O Options, Bulk Data or Subcase Information sections to indicate that the contents of another file are to be inserted into the input file at the exact location of the include command.
    - INSTANCE
      I/O Options EntryDefines instances of local parts to be included in the global model.
    - JOINTD
      I/O Options EntryOutput request. The JOINTD command can be used in the I/O Options section to request output of JOINTG Displacement.
    - JOINTF
      I/O Options EntryOutput request. The JOINTF command can be used in the I/O Options section to request output of JOINTG Forces.
    - KDYN
      I/O Options and Subcase Information Entry The KDYN command can be used in the I/O Options or Subcase Information sections to request dynamic stiffness output for all subcases or individual subcases respectively.
    - LIFE
      I/O Options and Subcase Information Entry Used in the I/O Options or Subcase Information sections to request output of fatigue life results for all fatigue subcases or individual fatigue subcases, respectively.
    - LOADLIB
      I/O Options EntryUsed to define the external libraries and external files to be loaded into OptiStruct.
    - MBFORCE
      I/O Options and Subcase Information Entry The MBFORCE command can be used in the I/O Options section to request force output for a set of joints and/or force elements from multibody dynamics subcases.
    - MDSDIR
      I/O Options EntryUsed to choose the location of the Altair Multiscale Designer™ installation.
    - MECHCHECK
      I/O Options and Subcase Information Entry The MECHCHECK command can be used in the I/O Options section to perform a massless mechanism check on the model.
    - MEFFMASS
      I/O Options EntryUsed to request output of modal effective mass, modal participation factors, and modal effective mass fractions in Normal Modes Analysis.
    - MODALDE
      I/O Options and Subcase Information Entry The MODALDE command can be used above the first SUBCASE or within a SUBCASE definition to request modal damping energy (the energy loss per cycle) output for all subcases or individual subcases, respectively.
    - MODALKE
      I/O Options and Subcase Information Entry The MODALKE command can be used above the first SUBCASE or within a SUBCASE definition to request modal kinetic energy output for all subcases or individual subcases, respectively.
    - MODALSE
      I/O Options and Subcase Information Entry The MODALSE command can be used above the first SUBCASE or within a SUBCASE definition to request modal strain energy output for all subcases or individual subcases, respectively.
    - MODEL
      I/O Options and Subcase Information Entry The MODEL command can be used in the I/O Options section to request output of only a subset of the model and related results for H3D and OUTPUT results files as well as for CMS superelements.
    - MONITOR
      I/O Options and Subcase Information Entry Controls the printing of monitor point data to the .monpnt file, whenever monitor points (MONPT1/MONPNT2/MONPNT3) are defined in the model.
    - MPCFORCE
      I/O Options and Subcase Information Entry The MPCFORCE command can be used in the I/O Options or Subcase Information sections to request multi-point force of constraint vector is output for all subcases or individual subcases, respectively.
    - MSGLMT
      I/O Options and Subcase Information Entry The MSGLMT command can be used in the I/O Options section to limit the number of ERROR, WARNING and INFORMATION messages output, or to elevate a WARNING or INFORMATION message to an ERROR.
    - NLDEBUG
      I/O Options and Subcase Information Entry The NLDEBUG series of parameters are available to help with debugging any nonlinear analysis model. These parameters simplify certain aspects of the model to help identify any possible issues.
    - NLLOAD
      I/O Options and Subcase Information Entry The NLLOAD entry can be used to request nonlinear load output for Transient Response Analysis for each time step for all subcases or individual subcases, respectively.
    - NOISEXYZ
      I/O Options and Subcase Information Entry Defines perturbation parameters for all X1, X2, and X3 grid point coordinate values which define the location of the grid points in the model. This entry applies to the X1, X2, and X3 fields of all GRID entries in the model.
    - NOUTPUT
      I/O Options EntryUsed to specify the segments for which results must be recovered and output, in cyclic symmetry analysis.
    - OFREQUENCY
      I/O Options and Subcase Information Entry The OFREQUENCY command can be used in the I/O Options or Subcase Information sections to request a set of frequencies for output requests for all subcases or individual subcases, respectively.
    - OLOAD
      I/O Options and Subcase Information Entry Used to request applied load vector output temperature load output, and applied power output for all subcases or individual subcases, respectively.
    - OMODES
      I/O Options and Subcase Information Entry Used in the I/O Options or Subcase Information sections to request a set of modes for output requests for all subcases or for individual subcases, respectively. This command is applicable for normal modes and linear buckling solution sequences only.
    - OTIME
      I/O Options and Subcase Information Entry Used in the I/O Options or Subcase Information sections to request a set of times for output requests for Transient Analysis for all subcases or individual subcases, respectively.
    - OUTFILE
      I/O Options and Subcase Information Entry Used in the I/O Options section to define the prefix for the results files output.
    - OUTPUT
      I/O Options EntryThe OUTPUT command can be used to control the format of results output and the creation of certain results files.
    - PFGRID
      I/O Options EntryThe PFGRID command can be used in the I/O Options section to request output of acoustic grid participation factors for all Modal Frequency Response subcases. The output will be in the .h3d file.
    - PFMODE
      I/O Options EntryUsed to request output of modal participation factors for all modal frequency response subcases.
    - PFPANEL
      I/O Options and Subcase Information Entry The PFPANEL command can be used in the I/O Options section to request output of acoustic panel participation factors for all Modal Frequency Response subcases.
    - PFPATH
      I/O Options and Subcase Information Entry The PFPATH command can be used in the I/O Options section for Transfer Path Analysis for a response at the connection points.
    - POWERFLOW
      I/O Options EntryUsed to request output of the power flow field.
    - PRESSURE
      I/O Options and Subcase Information Entry Used request displacement and pressure output for all subcases or individual subcases, respectively.
    - PRETBOLT
      I/O Options and Subcase Information Entry The PRETBOLT command can be used in the I/O Options or Subcase Information sections to request output of pretension force/adjustment values in the pretension bolts for all pretensioning and pretensioned subcases.
    - PROPERTY
      I/O Options and Subcase Information Entry The PROPERTY command can be used in the I/O Options section to request the output of the property definitions used in the final iteration of an optimization.
    - RBODY
      I/O Options and Subcase Information Entry The RBODY command can be used in the I/O Options section to select a rigid body or a combination of rigid bodies.
    - RCROSS
      I/O Options and Subcase Information Entry Used in the I/O Options section to request computation and output of cross-power spectral density functions for Random Response Analysis.
    - REQUEST
      I/O Options and Subcase Information Entry The REQUEST command can be used in the I/O Options or Subcase Information sections to select a multibody request definition to be used in a multibody problem.
    - RESPRINT
      I/O Options and Subcase Information Entry The RESPRINT command can be used in the I/O Options section to force all unretained responses of a certain type to be printed to the output file, provided they are referenced either as an objective or a constraint. This also applies to manufacturing constraints for composites.
    - RESTART
      I/O Options and Subcase Information Entry The RESTART command can be used in the I/O Options section to indicate that the current optimization is to be restarted from the final iteration of a previous optimization.
    - RESTARTR
      I/O Options EntryDefines the reading requests for nonlinear restart.
    - RESTARTW
      I/O Options and Subcase Information Entry The RESTARTW entry can be used in the I/O Options section to define the control parameters for nonlinear restart.
    - RESULTANT
      I/O Options and Subcase Information Entry Enables the output of section resultant results.
    - RIGID
      I/O Options and Subcase Information Entry The RIGID command can be used in the I/O Options section to select the constraint processing method for RBAR, RROD, RBE1, RBE2, RBE3, RSPLINE, RSSCON, RBODY and MPC entries.
    - RNFLOW
      I/O Options and Subcase Information Entry Used to request fatigue damage results output for all fatigue subcases or individual fatigue subcases, respectively.
    - SACCELERATION
      I/O Options and Subcase Information Entry The SACCELERATION command can be used in the I/O Options or Subcase Information sections to request the form and type of modal participation accelerations output for all subcases or individual subcases, respectively.
    - SCREEN
      I/O Options and Subcase Information Entry The SCREEN command can be used in the I/O Options section to control the output of model, analysis, and optimization information to the Unix or DOS shell.
    - SDISPLACEMENT
      I/O Options and Subcase Information Entry The SDISPLACEMENT command can be used in the I/O Options or Subcase Information sections to request the form and type of modal participation displacements output for all subcases or individual subcases, respectively.
    - SENSITIVITY
      I/O Options and Subcase Information Entry The SENSITIVITY command can be used in the I/O Options section to request the output of the responses and sensitivities for size and shape design variables to a Microsoft Excel spreadsheet.
    - SENSOUT
      I/O Options and Subcase Information Entry The SENSOUT command can be used in the I/O Options section to control the frequency of output of responses and sensitivities for size and shape design variables to a Microsoft Excel spreadsheet.
    - SHAPE
      I/O Options and Subcase Information Entry The SHAPE command can be used in the I/O Options section to request altered shape output for a shape optimization.
    - SINTENS
      I/O Options and Subcase Information Entry Used to request Sound Intensity output for all frequency response subcases. The SINTENS command can be used in the I/O Options or Subcase Information sections to request Sound Intensity output for all subcases or individual subcases, respectively.
    - SKIP
      I/O Options and Subcase Information Entry Requests skipping certain lines from the analysis.
    - SPCFORCE
      I/O Options and Subcase Information Entry Used to request single-point force of constraint vector output for all subcases or individual subcases, respectively.
    - SPL
      I/O Options and Subcase Information Entry The SPL command can be used in the I/O Options or Subcase Information sections to request Sound Pressure output for all subcases or individual subcases, respectively. SPL can only be requested for frequency response subcases.
    - STRAIN
      I/O Options and Subcase Information Entry Used to request strain output for all subcases or individual subcases, respectively.
    - STRESS / ELSTRESS
      I/O Options and Subcase Information Entry Used to request stress output for all subcases or individual subcases, respectively.
    - SUBTITLE
      I/O Options and Subcase Information Entry The SUBTITLE command can be used in the I/O Options or Subcase Information sections to define the subtitle for all subcases or for individual subcases, respectively.
    - SVELOCITY
      I/O Options and Subcase Information Entry The SVELOCITY command can be used in the I/O Options or Subcase Information sections to request the form and type of modal participation velocities output for all subcases or individual subcases, respectively.
    - SYSSETTING
      I/O Options EntryUsed to alter system settings. Any setting defined here may be over-ridden by command line arguments (Run Options). Most of these options can also be specified in one of the config files (Configuration File).
    - TCURVE
      I/O Options and Subcase Information Entry The TCURVE command can be used in the I/O Options section to define the plot title for XYPLOT output from a Random Response Analysis.
    - THERMAL
      I/O Options and Subcase Information Entry The THERMAL command can be used in the I/O Options or Subcase Information sections to request temperature output for all heat transfer analysis subcases or individual heat transfer analysis subcases, respectively.
    - THICKNESS
      I/O Options and Subcase Information Entry The THICKNESS command can be used in the I/O Options section to request thickness output for elements referencing a PSHELL, PCOMP or PCOMPP properties in size (parameter)/free-size optimization and analysis runs.
    - TITLE
      I/O Options and Subcase Information Entry The TITLE command can be used in the I/O Options section to define the title for the OptiStruct job.
    - TMPDIR
      I/O Options and Subcase Information Entry The TMPDIR command is used in the I/O Options section to choose the directory in which the scratch files are to be written.
    - TOTALFORCE
      I/O Options and Subcase Information Entry Used to request the total force (summation of single-point force of constraint and applied load) output for all subcases or individual subcases, respectively.
    - TRIMF
      I/O Options and Subcase Information Entry Used to specify options for the output of trim loads from a static aeroelastic analysis as FORCE/MOMENT Bulk Data Entries.
    - TTERM
      I/O Options and Subcase Information Entry The TTERM command can be used to define the termination time.
    - UNITS
      I/O Options and Subcase Information Entry The UNITS command can be used in the I/O Options section to define a system of units for the model.
    - VELOCITY
      I/O Options and Subcase Information Entry The VELOCITY command can be used in the I/O Options or Subcase Information sections to request velocity vector output for all subcases or individual subcases, respectively.
    - VOLTAGE
      I/O Options and Subcase Information Entry Used to output electric potential results in electrical analysis.
    - XTITLE
      I/O Options and Subcase Information Entry The XTITLE command can be used in the I/O Options section to define the x-axis label for XYPUNCH or XYPLOT output from a Random Response Analysis.
    - XYPEAK / XYPLOT / XYPUNCH
      I/O Options EntryThe XYPEAK, XYPLOT, and XYPUNCH commands can be used in the I/O Options section to request output from a Random Response Analysis. The XYPUNCH command can also be used with the RESPONSE plot-type to request .pch file output from a Frequency Response Analysis.
    - YTITLE
      I/O Options and Subcase Information Entry The YTITLE command can be used in the I/O Options section to define the y-axis label for XYPUNCH or XYPLOT output from a Random Response Analysis.
  - Subcase Information Section
    Alphabetical listing of the Subcase Information Entries.
  - Bulk Data Section
    Alphabetical listing of the Bulk Data Entries.
  - Element Quality Check
    In order to prevent analyses from being carried out on badly discretized models, an element quality check is incorporated into the pre-processing phase.
  - Material Property Check
    In order to prevent analyses from being carried out on models with poor material definitions, a material property check is incorporated into the pre-processing phase. The material property check is controlled by the CHECKMAT parameter (see the PARAM input format).
- Output Data
- Legacy Data
Example Guide
The OptiStruct Example Guide is a collection of solved examples for various solution sequences and optimization types and provides you with examples of the real-world applications and capabilities of OptiStruct.
Verification Problems
This manual presents solved verification models including NAFEMS problems.
Frequently Asked Questions
This section provides quick responses to typical and frequently asked questions regarding OptiStruct.

HYBDAMP

I/O Options and Subcase Information Entry The HYBDAMP command can be used in the I/O Options section to request modal damping as a function of the natural frequency of the model in Dynamic Analysis.

Format

HYBDAMP = option

Definitions


Argument	Options	Description
`option`	<SID> No default	SID Set identification of HYBDAMP in Bulk Data Entry.

Comments

HYBDAMP can be set at the global level in the I/O Options section. It can exist only once in the I/O Options section.