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What's New
View new features for OptiStruct
2019 .
Overview
OptiStruct ® is an industry proven, modern structural analysis solver for linear and nonlinear structural problems under static
and dynamic loadings.
Tutorials
Discover OptiStruct functionality with interactive tutorials.
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 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.
Bulk Data Entries by Function for Explicit Analysis
Guidelines for using Bulk Data Entries are listed in Bulk Data Guidelines.
I/O Options Section
Alphabetical listing of the I/O Options Entries.
Subcase Information Section
Alphabetical listing of the Subcase Information Entries.
A2GG
Subcase Information Entry The A2GG command can be used in the Subcase Information section to select a direct input fluid-structure coupling matrix.
ANALYSIS
Subcase Information Entry The ANALYSIS command can be used in the I/O Options section to request that only a finite element analysis be performed (optimization
input is ignored). It may also be used in the I/O Options or Subcase Information sections to identify the solution
sequence for all subcases or for individual subcases, respectively.
B2GG
Subcase Information Entry The B2GG command can be used in the Subcase Information section to select a direct input viscous damping matrix.
CMETHOD
Subcase Information Entry The CMETHOD command can be used in the Subcase Information section to select the method for complex eigenvalue extraction.
CMSMETH
Subcase Information Entry The CMSMETH command can be used in the Subcase Information section to request that only a component mode synthesis solution be
performed and to select a component mode synthesis method definition to be used.
CNTNLSUB
Subcase Information Entry The CNTNLSUB command can be used in the Subcase Information section to continue a nonlinear solution from a preceding
nonlinear subcase, and thus create complex loading sequences.
CNTSTB
Subcase Information Entry The CNTSTB command can be used in the Subcase Information section to activate stabilization of surface-to-surface (S2S) contact
and large displacement node-to-surface (N2S) contact for this subcase. It is used only for Small Displacement Nonlinear
Analysis.
DEFORM
Subcase Information Entry The DEFORM command can be used in the Subcase Information section to select an element deformation set.
DESOBJ
Subcase Information Entry To select a single response definition as the objective function of an optimization, or to select system response
definitions when the objective function is the least squares sum of these definitions. The DESOBJ command also indicates if this response is to be minimized or maximized.
DESSUB
Subcase Information Entry The DESSUB command can be used in the Subcase Information section, within a subcase definition, to select a constraint set
that is subcase dependent.
DESVAR
Subcase Information Entry The DESVAR command can be used in the Subcase Information section to select a set of design variables for use in an
optimization run.
DLOAD
Subcase Information Entry The DLOAD command can be used in the Subcase Information section to select a dynamic load to be applied in a transient and
frequency response analysis subcase. The DLOAD command can also be used to select a user-defined loading curve to be applied in a nonlinear static analysis
subcase.
EIGVRETRIEVE
Subcase Information Entry The EIGVRETRIEVE command can be used in the Subcase Information section of Modal Frequency Response or Modal Transient Response
analysis to retrieve eigenvalue and eigenvector results of a previously run Normal Modes Analysis from an external
data file (.eigv ).
EIGVSAVE
Subcase Information Entry The EIGVSAVE command can be used in the Subcase Information section to output eigenvalue and eigenvector results of a Normal
Modes Analysis to an external data file (.eigv ).
ESLTIME
Subcase Information Entry The ESLTIME command can be used in the Subcase Information section to select particular time steps for geometric nonlinear
response ESLM optimization or Multibody Dynamics ESLM optimization.
EXCLUDE
Subcase Information Entry The EXCLUDE command can be used in the Subcase Information section to select a set of elements to be excluded from a Linear
Buckling Analysis.
FATDEF
Subcase Information Entry The FATDEF command can be used in the Subcase Information section to select a FATDEF Bulk Data Entry that will define the elements, and their associated fatigue properties, to be considered for
Fatigue Analysis.
FATPARM
Subcase Information Entry The FATPARM command can be used in the Subcase Information section to select a FATPARM Bulk Data Entry that will define the parameters to be used for a Fatigue Analysis.
FATSEQ
Subcase Information Entry The FATSEQ command can be used in the Subcase Information section to indicate that a subcase is a fatigue analysis subcase
and to select a FATSEQ Bulk Data Entry that will define the loading sequence for the Fatigue Analysis.
FLLWER
Subcase Information Entry The FLLWER command can be used in the Subcase Information section to activate activate updating the node forces introduced by
a pressure load.
FREQUENCY
Subcase Information Entry The FREQUENCY command can be used in the Subcase Information section to select the set of forcing frequencies to be solved
in a frequency response problem.
FSI
Subcase Information Entry Identifies a FSI Bulk Data Entry to run Fluid-Structure Interaction Analysis with AcuSolve for a Linear Transient Heat Transfer Subcase or Nonlinear Direct Transient Analysis Subcase.
GLOBSUB
Subcase Information Entry The GLOBSUB entry can be used in the Subcase Information section to select a subcase that references the global structure for
Local-Global Analysis and a set of grid points in the local structure that defines the cut surface for displacement.
GROUNDCHECK
Subcase Information Entry The GROUNDCHECK command can be used in the Subcase Information section to perform a Grounding Check Analysis on the stiffness
matrix to expose unintentional constraints by moving the model rigidly.
IC
Subcase Information Entry The IC command may be used in the Subcase Information section to select initial conditions for transient (structural and
heat transfer) and explicit analysis.
IDGLOBAL
Subcase Information Entry The IDGLOBAL entry can be used in the I/O Options section to convert all entries of the specified type into corresponding
global entries.
INISTRS
I/O options and subcase information entry Define initial stresses of elements for nonlinear quasi-static analysis.
INVEL
Subcase Information Entry Used to select a multibody initial velocity set to be applied in a multibody problem.
K2GG
Subcase Information Entry The K2GG command can be used in the Subcase Information section to select a direct input stiffness matrix.
K2PP
Subcase Information Entry The K2PP command can be used in the Subcase Information section to select a direct input stiffness matrix, which is not
included in normal modes.
K42GG
Subcase Information Entry The K42GG command can be used in the Subcase Information section to select a direct input structural element damping
matrix.
LABEL
Subcase Information Entry The LABEL command can be used in the Subcase Information section to provide a subcase with a label.
LOAD
Subcase Information Entry The LOAD command can be used in the Subcase Information section to select a static load set to be applied in linear static
solutions.
LOADJG
Subcase Information Entry Used in the Subcase Information section to select a load set to be applied to joints which are defined via the JOINTG Bulk Data Entry.
LOCATE
Subcase Information Entry The LOCATE entry can be used in the Subcase information section to select subcase-specific location (geometric position) of
each part in the model.
M2GG
Subcase Information Entry The M2GG command can be used in the Subcase Information section to select a direct input mass matrix.
MBSIM
Subcase Information Entry The MBSIM command can be used in the Subcase Information section to select a Multibody simulation definition to be applied
in a Multibody problem.
METHOD
Subcase Information Entry The METHOD command can be used in the Subcase Information section to select a method for real eigenvalue extraction.
MFLUID
Subcase Information Entry The MFLUID command can be used in the Subcase Information section to select the parameters and damp elements and activate
the calculation of virtual fluid mass.
MINMAX or MAXMIN
Subcase Information Entry The MINMAX or MAXMIN commands can be used in the Subcase Information section to select normalized response or system identification definitions
as the objective function for a "Minmax" or "Maxmin" optimization.
MLOAD
Subcase Information Entry The MLOAD command can be used in the Subcase Information section to select a Multibody load set to be applied in a
Multibody problem.
MODCHG
Subcase Information Entry The MODCHG command can be to remove and/or reactivate contact interfaces and/or elements for this subcase. It is used
only for nonlinear analysis.
MODESELECT
Subcase Information Entry The MODESELECT command can be used in the I/O Options or the Subcase Information section to select a subset of computed
modes in modal dynamic analysis subcases.
MODEWEIGHT
Subcase Information Entry The MODEWEIGHT command can be used in the Subcase Information section to define a multiplier for computed eigenvalues that
are to be used in the calculation of the "weighted reciprocal eigenvalue" and "combined compliance index" optimization
responses.
MODTRAK
Subcase Information Entry The MODTRAK command can be used in the Subcase Information section to control mode tracking.
MONITOR
Subcase Information Entry Can be used to activate Nonlinear Displacement Monitoring for a subcase by referencing a corresponding MONITOR Bulk Data Entry.
MOTION
Subcase Information Entry The MOTION command can be used in the Subcase Information section to select a Multibody motion set to be applied in a
multibody problem.
MOTNJG
Subcase Information Entry Used to select the motion applied to corresponding joints.
MPC
Subcase Information Entry The MPC command can be used in the Subcase Information section to select a multi-point constraint set.
NLADAPT
Subcase Information Entry The NLADAPT entry can be used in the Subcase Information section to select the parameters used for Large Displacement
Nonlinear Quasi-static Analysis, Small Displacement Nonlinear Quasi-Static Analysis, and Nonlinear Transient Analysis.
NLMON
Subcase Information Entry This NLMON Subcase Information Entry can be used to activate Nonlinear Monitoring for a subcase by referencing a corresponding
NLMON Bulk Data Entry.
NLOAD
Subcase Information Entry The NLOAD command can be used in the Subcase Information section to select a time dependent load to be applied in Explicit
Dynamic Analysis problem.
NLOUT
Subcase Information Entry The NLOUT entry can be used in the Subcase Information section to select the incremental result output parameters used for
Nonlinear Static Analysis and Nonlinear Transient Analysis.
NLPARM
Subcase Information Entry The NLPARM command can be used to activate nonlinear solution methods for this subcase and to select the parameters used for
Nonlinear Quasi-static Analysis, and Nonlinear Direct Transient Analysis.
NONLINEAR
Subcase Information Entry The NONLINEAR command can be used in the Subcase Information section to select a nonlinear dynamic load set for linear and
small displacement nonlinear direct transient analyses.
NORM
Subcase Information Entry The NORM command can be used in the Subcase Information section to define a normalization factor used in the computation of
the "combined compliance index" optimization response.
NSGE
Subcase Information Entry The NSGE command can be used in the Subcase Information section to select a non-structural damping set. The selector command
must appear before the first SUBCASE statement.
NSM
Subcase Information Entry The NSM command can be used in the Subcase Information section to select a non-structural mass set for mass generation. The
selector command must appear before the first SUBCASE statement.
P2G
Subcase Information Entry The P2G command is used before the first subcase to select a direct input load matrix.
P2GSUB
Subcase Information Entry The P2GSUB command is used in a specific subcase to select a direct input load matrix.
PEAKOUT
Subcase Information Entry The PEAKOUT command can be used in the Subcase Information section to select the criteria for automatic identification of
loading frequencies at which result peaks occur. Output result output may then be requested at these "peak" loading
frequencies. This entry is supported for frequency response solution sequences only.
POST
I/O Options and Subcase Information Entry Used to request subcase-specific output to separate files.
PRETENSION
Subcase Information Entry The PRETENSION command can be used in the Subcase Information section to select and activate a pretensioning bolt load.
RADSND
Subcase Information Entry The RADSND command can be used in the Subcase Information section to select RADSND Bulk Data to specify sound generation panels and microphone field locations.
RANDOM
Subcase Information Entry Selects the RANDPS and RANDT1 Bulk Data Entries to be used in Random Response Analysis.
REPCASE
Subcase Information Entry The REPCASE command can be used in the Subcase Information section to indicate the start of a repeated subcase definition. This
is used for multiple output requests of the same type for the same subcase.
REPGLB
Subcase Information Entry The REPGLB command can be used in the Subcase Information section, before the first subcase statement, to select a report set
that is not subcase dependent.
REPSUB
Subcase Information Entry The REPSUB command can be used in the Subcase Information section, within a subcase definition, to select a report set that
is subcase dependent.
RESVEC
Subcase Information Entry The RESVEC command can be used in the Subcase Information section to control the calculation of residual vectors.
RGYRO
Subcase Information Entry Identifies a RGYRO Bulk Data Entry that contains information required to implement Rotor Dynamics in Modal Complex Eigenvalue Analysis,
Modal Frequency Response Analysis, Static Analysis, Linear Direct Transient Response Analysis and/or Small-Displacement
Nonlinear Direct Transient Response Analysis.
RSPEC
Subcase Information Entry The RSPEC command can be used in the Subcase Information section to reference combination rules, excitation degrees-of-freedom,
and input spectra for use in response spectrum analysis.
RWALL
Subcase Information Entry The RWALL command can be used in the Subcase Information section to select rigid walls for Explicit Dynamic Analysis.
SDAMPING
Subcase Information Entry The SDAMPING command can be used in the Subcase Information section to apply modal damping as a function of natural frequency
in modal solutions.
SEALL
Subcase Information Entry Identifies the Superelements for Generation and Assembly for One-Step Superelement Analysis.
SEDR
Subcase Information Entry Defines the Superelement Identification Numbers for which Data Recovery is performed for One-Step Superelement Analysis.
SEINTPNT
Subcase Information Entry The SEINTPNT command can be used in the Subcase Information section to select a set of interior DOF of superelements to be converted to exterior DOF .
SOLVTYP
Subcase Information Entry The SOLVTYP command can be used in the Subcase Information section to select the solver for linear, nonlinear static, and dynamic
subcases.
SPC
Subcase Information Entry The SPC command can be used in the Subcase Information section to select a single-point constraint set.
STATSUB
Subcase Information Entry The STATSUB command can be used in the Subcase Information section to select a static solution subcase.
SUBCASE
Subcase Information Entry The SUBCASE command can be used in the Subcase Information section to indicate the start of a new subcase definition.
SUBCOM
Subcase Information Entry Delimits and identifies a combination subcase.
SUBMODEL
Subcase Information Entry The SUBMODEL entry can be used in the Subcase Information section to select a submodel as a set of elements. Subcase entries specific
to the selected element set can be used to solve the submodel without affecting the rest of the structure.
SUBSEQ
Subcase Information Entry Gives the coefficients for forming a linear combination of the previous static subcases.
SUPORT1
Subcase Information Entry The SUPORT1 command can be used in the Subcase Information section to select a fictitious support set to be applied to the model.
TEMPERATURE
Subcase Information Entry Selects the temperature set to be used in either material property calculations or thermal loading.
TSTEP
Subcase Information Entry The TSTEP command can be used in the Subcase Information section to select integration for transient analysis.
TSTEPNL
Subcase Information Entry The TSTEPNL command can be used in the Subcase Information section to select integration and other parameters for nonlinear implicit
dynamics analysis.
TSTRU
Subcase Information Entry The TSTRU command can be used in the Subcase Information section to assign a temperature set identification number to the resulting
nodal temperatures of a steady-state heat transfer analysis or the last time step of a transient heat transfer
analysis.
WEIGHT
Subcase Information Entry The WEIGHT command can be used in the Subcase Information section to define a weighting factor (multiplier) for the compliances
of individual linear static solution subcases, which are used in the calculation of the "weighted compliance" and
"combined compliance index" optimization responses.
XHIST
Subcase Information Entry The XHIST command can be used in the Subcase Information section to select time history output for Explicit Dynamic Analysis.
XSTEP
Subcase Information Entry The XSTEP command can be used in the Subcase Information section to activate the explicit solution method for this subcase
and to select the parameters used for explicit analysis.
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 .
HyperWorks Solver Run Manager
The HyperWorks Solver Run Manager is a unified utility that allows the user to start different HyperWorks Solvers.
POST
I/O Options and Subcase Information
Entry Used to request subcase-specific output to separate
files.
Definitions
Argument
Options
Description
tofile TOFILE No default
Keyword that indicates the
output file "label" will follow.
label <label> No default
The user-specified "label"
that will be appended to the
<model_filename> in the generated
subcase-specific output file.
Currently only subcase-specific H3D, OP2 and
PCH files are available.
For subcase-specific H3D output,
POST ,TOFILE command should be used in
conjunction with OUTFILE ,H3D. This is
currently supported for Static analysis only.
For subcase-specific OP2 output, the
POST ,TOFILE command should always be used in
conjunction with OUTFILE ,OP2 or PARAM, POST ,-1.
For subcase-specific PCH output, the
POST ,TOFILE command should be used in
conjunction with OUTFILE ,PCH. This is currently
supported for Static analysis only.
POST ,TOFILE can be used in
conjunction with the REPCASE entry to allow output of different
result types of a subcase in multiple output files.