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.
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.
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 Entry Defines acceleration loads to all grids in the model. These loads can either be constant or vary in a particular direction
over sections of the model.
Bulk Data Entry Defines static acceleration loads at a specific SET of GRID points in the model. Additionally, scale factors for varying
direction acceleration loads can be defined using tabular data.
Bulk Data Entry Specifies an aerodynamic control surface as a member of the set of aerodynamic extra points. The forces associated
with this controller will be derived from rigid rotation of the aerodynamic model about the hinge line(s).
Bulk Data Entry Indicates the beginning of data that is used to describe a specific entity (or entities) for inclusion in a model.
The BEGIN entry is used in conjunction with the END entry to define the data required for a specific entity.
Bulk Data Entry Defines an aerodynamic macro element (panel) in terms of two leading edge locations and side chords. This is used
for Vortex Lattice Method (VLM) and Doublet Lattice Method (DLM) in subsonic aeroelastic analysis.
Bulk Data Entry Defines a current density on the face of solid elements (HEXA, PENTA, TETRA, PYRA) or on the side of shell elements
(TRIA3, TRIA6, QUAD4, QUAD8), in Electrical analysis.
Bulk Data Entry Defines a scalar spring element of the structural model without reference to a property entry. The corresponding properties
on this entry are not affected by translational and rotational stiffness limits specified using PARAM,ELASSTIF.
Bulk Data Entry Defines a scalar spring element that is connected only to scalar points without reference to a property entry. The
corresponding properties on this entry are not affected by translational and rotational stiffness limits specified
using PARAM,ELASSTIF.
Bulk Data Entry Defines the CMS (Component Mode Synthesis) method, frequency upper limit, number of modes, and starting SPOINT ID to be used in a CMS solution.
Bulk Data Entry Defines parameters for stabilization control of contact (S2S and N2S) and gap elements (CGAP/CGAPG). This entry is supported with nonlinear static and nonlinear transient analysis types for both small and
large displacement cases.
Bulk Data Entry Define equivalence for degrees of freedom of grid points of two sections of the same model (Format 2) or different
parts in a Parts and Instances Model (Format 1) within a specified tolerance.
Bulk Data Entry Defines Free convection via automatic generation of free convection entries. This entry also supports subcase-dependent
free convection.
Bulk Data Entry Defines a cylindrical coordinate system using three grid points. The first point is the origin, the second lies on the Z-axis, and the third lies in the X-Z plane.
Bulk Data Entry Defines a rectangular coordinate system using three grid points. The first point is the origin, the second lies on the Z-axis, and the third lies in the X-Z plane.
Bulk Data Entry Defines a spherical coordinate system using three grid points. The first point is the origin, the second lies on the Z-axis, and the third lies in the X-Z plane.
Bulk Data Entry Defines a rectangular coordinate system using three grid points. The first point is the origin, the second lies on the X-axis, and the third lies in the X-Y plane.
Bulk Data Entry CTRIAR entry is equivalent to CTRIA3. Unlike other Nastran codes, a 6 degrees-of-freedom per node formulation is used for all shell elements.
Bulk Data Entry Define real, discrete design variable values for discrete variable optimization or to define relative rotor spin rates
in rotor dynamics.
Bulk Data Entry Defines the time delay term in the equations of the dynamic loading function. DELAY is used in conjunction with RLOAD1, RLOAD2, TLOAD1, and TLOAD2 entries.
Bulk Data Entry Defines a link between a DIM# field on a PBARL or PBEAML property and either the thickness on a PSEC definition or the y or z coordinate on a GRIDS definition; it is used in the definition of arbitrary beam cross-sections.
Bulk Data Entry Defines parameters for filling a space with lattice-based unit cells. The presence of this entry also activates the
creation of unit cells to fill the target volume.
Bulk Data Entry Defines a link of one design variable to one or more other design variables defined by a DEQATN card. The equation inputs come from the referenced DESVAR values and the constants defined on the DTABLE card.
Bulk Data Entry Defines a dynamic loading condition for frequency response problems as a linear combination of load sets defined via
RLOAD1 and RLOAD2 entries, or for transient problems as a linear combination of load sets defined via TLOAD1 and TLOAD2 entries, or acoustic source ACSRCE entries.
Bulk Data Entry Defines direct input matrices related to grid points. The matrix is defined by a single header entry and one or more
column entries. A column entry is required for each column with non-zero elements.
Bulk Data Entry Defines the phase lead term in the equation of the dynamic loading function. DPHASE is used in conjunction with RLOAD1 and RLOAD2 entries.
Bulk Data Entry Used in the Bulk Data section to report responses, defined by DRESP1, DRESP2 and DRESP3 cards, to the output file, which are not constrained or used as the objective function, as defined by the optimization
problem.
Bulk Data Entry A response or a set of responses that are the result of a design analysis iteration. These responses can
be used as a design objective or as design constraints.
Bulk Data Entry Relates design variables to an analysis model element property using a relationship defined by a DEQATN card. The equation inputs come from the referenced DESVAR values and constants defined on a DTABLE card.
Bulk Data Entry Relates a design variable to an analysis model loading using a relationship defined by a DEQATN card. The equation inputs come from the referenced DESVAR values and the constants defined on the DTABLE card.
Bulk Data Entry Relates a design variable to properties of MBD entities using a relationship defined by a DEQATN card. The equation inputs come from the referenced DESVAR values and the constants defined on the DTABLE card.
Bulk Data Entry Relates design variables to an analysis model material property using a relationship defined by a DEQATN card. The equation inputs come from the referenced DESVAR values and constants defined on a DTABLE card.
Bulk Data Entry Relates a design variable to an analysis model property using a relationship defined by a DEQATN card. The equation inputs come from the referenced DESVAR values and the constants defined on the DTABLE card.
Bulk Data Entry The END Bulk Data Entry indicates the end of data that is used to describe a specific entity (or entities) for inclusion
in a model. The END entry is used in conjunction with the BEGIN entry to define the data required for a specific entity.
Bulk Data Entry Defines a combined time step selection set as a union of selected time steps defined via ESLTIME entries for Geometric Nonlinear ESLM optimization or a Multibody Dynamics ESLM optimization.
Bulk Data Entry Defines a set of frequencies to be used in the solution of frequency response problems by specification of a starting
frequency, frequency increment, and the number of increments desired.
Bulk Data Entry Defines a set of frequencies to be used in the solution of frequency response problems by specification of a starting
frequency, final frequency, and the number of logarithmic increments desired.
Bulk Data Entry Defines a set of frequencies for the modal method of frequency response analysis by specifying the number of frequencies
between modal frequencies.
Bulk Data Entry Defines a set of frequencies for the modal method of frequency response analysis by specifying the amount of "spread"
around each modal frequency and the number of equally spaced frequencies within the spread.
Bulk Data Entry Defines a set of frequencies for the modal method of frequency response analysis by specification of a frequency range
and fractions of the natural frequencies within that range.
Bulk Data Entry Defines parameters that control connectivity and configuration checks for gap elements (CGAP and CGAPG). Most of these parameters also affect contact elements that are automatically created on CONTACT interfaces - see individual descriptions for details.
Bulk Data Entry Defines the stiffness, flexibility, mass, viscous damping, or structural damping of a general element connected to
an arbitrary number of grids.
Bulk Data Entry Defines equivalence for all degrees of freedom of grid points of two different subsets of without any requirement
that these two subsets are closely located to one another.
Bulk Data Entry Defines the gravity vectors for use in determining gravity loading for the static structural model. It can also be used
to define the EXCITEID field (Amplitude "A") of dynamic loads in RLOAD1, RLOAD2, TLOAD1, TLOAD2 and NLOAD1 Bulk Data Entries for dynamic solution sequences.
Bulk Data Entry Defines the location of a geometric grid point of the structural model, the
directions of its displacement, and its permanent single-point constraints.
Bulk Data Entry The INSTNCE Bulk Data Entry can be used to define the location of a part in the global structure. Each INSTNCE entry should reference a unique part name.
Bulk Data Entry Defines a static load as a linear combination of load sets defined via FORCE, MOMENT, FORCE1, MOMENT1, PLOAD, PLOAD1, PLOAD2, PLOAD4, RFORCE, DAREA, ACCEL, ACCEL1, ACCEL2, GRAV and LOADADD entries.
Bulk Data Entry The LOCATE Bulk Data Entry can be used to define the location of a part in the global structure. Each LOCATE entry should reference a unique part name. LOCATE Bulk Data Entries are activated in each subcase by the LOCATE Subcase Entry.
Bulk Data Entry Defines the material properties for linear, temperature-independent, and orthotropic materials used by the CTAXI, CTRIAX6, and CQAXI axisymmetric elements, and CTPSTN and CQPSTN plane strain elements.
Bulk Data Entry Defines the material properties for linear, temperature-independent, and orthotropic materials for solid elements
in terms of engineering constants.
Bulk Data Entry Defines material properties and parameters through an interface to AltairMultiscale Designer™ allowing you to include a much wider range of different material models.
Bulk Data Entry Defines additional material properties for Johnson-Cooke elastic-plastic
material for geometric nonlinear analysis. This is an elasto-plastic law with strain rate
and temperature effects.
Bulk Data Entry Defines additional material properties for Honeycomb material for geometric
nonlinear analysis. This law is only applicable to solid elements.
Bulk Data Entry Defines additional material properties for Ogden, Mooney-Rivlin material for geometric nonlinear analysis. This material
is used to model rubber, polymers, and elastomers.
Bulk Data Entry Defines additional material properties for Hill Orthotropic material for geometric nonlinear analysis. This law is
only applicable to two-dimensional elements.
Bulk Data Entry Defines additional material properties for Hyper-visco-elastic material for geometric
nonlinear analysis. This material is used to model rubber, polymers, and elastomers. This
material is compatible with solid and shell elements.
Bulk Data Entry Defines additional material properties for Honeycomb
material for geometric nonlinear analysis. This law is only applicable to
solid elements.
Bulk Data Entry Defines additional material properties for Ogden material for geometric
nonlinear analysis. This material is used to model rubber, polymers, and elastomers.
Bulk Data Entry Used to define properties of a virtual fluid mass. A virtual fluid mass mimics the mass effect of an incompressible
inviscid fluid in contact with a structure.
Bulk Data Entry To input a table of Mach number (M) and reduced frequency (K) pairs for aerodynamic matrix calculation, in unsteady
aerodynamic analysis.
Bulk Data Entry Defines a multibody as a linear combination of load sets defined via GRAV, MBFRC, MBFRCC, MBFRCE, MBMNT, MBMNTC, MBMNTE, MBSFRC, MBSFRCC, MBSFRCE, MBSMNT, MBSMNTC, and MBSMNTE.
Bulk Data Entry Defines an integrated load monitor point at a point (x,y,z) in a user-defined coordinate system. The integrated loads
about this point over the associated loads will be computed and printed to the .monpnt file.
Bulk Data Entry Defines parameters for energy variables printout for implicit nonlinear static, implicit nonlinear transient analyses,
and explicit dynamic analysis.
Bulk Data Entry Defines properties for CAERO1 panels. This is used for Vortex Lattice Method (VLM) and Doublet Lattice Method (DLM) in subsonic aeroelastic analysis.
Bulk Data Entry Defines up to four sets of grid points or elements as panels for panel participation output for a frequency response
analysis of a coupled fluid-structural model.
Bulk Data Entry Defines the various nominal property values for a generalized spring-damper-mass
structural element. This property is not affected by translational and rotational stiffness
limits specified using PARAM, BUSHSTIF.
Bulk Data Entry Defines the external function to be called to calculate time and temperature-dependent free-convection coefficient
in a convection element.
Bulk Data Entry Defines criteria used for the automatic identification of loading frequencies at which result peaks occur. Other result
output may then be requested at these "peak" loading frequencies. This feature is only supported for frequency
response solution sequences.
Bulk Data Entry Defines the frequency dependent property values for a PELAS Bulk Data Entry. It can also be used to define a nonlinear spring for Nonlinear Analysis via the TKNID field.
Bulk Data Entry Defines a connection between opposite edges/faces of the structure. This entry is used to apply Periodic Boundary
Conditions to the model.
Bulk Data Entry Defines the thickness, material, blank holder, binder and Forming Limit Curve references for a shell property in a
one-step stamping simulation.
Bulk Data Entry Defines a static pressure load on a triangular or quadrilateral element. It can also be used to define the EXCITEID field (Amplitude "A") of dynamic loads in RLOAD1, RLOAD2, TLOAD1 and TLOAD2 Bulk Data Entries.
Bulk Data Entry Defines concentrated, uniformly distributed, or linearly distributed applied loads to the CBAR or CBEAM elements or a SET of such elements at user-chosen points along the axis.
Bulk Data Entry Defines a static surface traction on the CQAXI, CTAXI and CTRIAX6 axisymmetric elements. The PLOADX1 entry can be defined as follower loads in Large Displacement Nonlinear Analysis.
Bulk Data Entry Defines the properties of nonlinear hyperelastic solid elements, referenced by CHEXA, CPENTA, and CTETRA Bulk Data Entries. The MATHE hyperelastic material can be referenced to define corresponding material properties.
Bulk Data Entry Defines parameters that control initial loading conditions on pretension sections for 1D and 3D bolt pre-tensioning.
These parameters also control the printing of diagnostic information about pretension sections.
Bulk Data Entry Defines the external function called to calculate time and temperature-dependent rate of volumetric heat addition
in a conduction element.
Bulk Data Entry Defines a rigid body whose independent degrees-of-freedom are specified at a single grid point and whose dependent degrees-of-freedom
are specified at an arbitrary number of grid points.
Bulk Data Entry Geometrically maps parts (for example, elements and grids) from one location to another. This entry allows you to
define mapping as MOVE (translation), ROTATE, MIRROR, or MATCH (as an arbitrary transformation which matches grids from one group to similar grids in another group).
Bulk Data Entry Defines a static loading condition due to a centrifugal force field. It can also be used to define the EXCITEID field (Amplitude "A") of dynamic loads in RLOAD1, RLOAD2 , TLOAD1 and TLOAD2 Bulk Data Entries.
Bulk Data Entry Includes data required to perform Rotor Dynamics analysis in Modal Frequency Response Analysis and/or Modal Complex
Eigenvalue Analysis. The RGYRO Bulk Data Entry is referenced by a corresponding RGYRO Subcase Information Entry in a specific subcase.
Bulk Data Entry Defines the relative spin rates between rotors and rotor damping parameters during a rotor dynamic analysis in Static,
Modal Complex Eigenvalue or Frequency Response solution sequences.
Bulk Data Entry Defines a partitioned superelement relocation by listing three noncolinear grids in the superelement and three corresponding
grids not belonging to the superelement.
Bulk Data Entry Defines a set of grids, elements, design variables, MBD entities, mode numbers, frequencies or times for reference
by other input definitions.
Bulk Data Entry This entry can be used to define single-point constraints, enforced displacements for Structural analysis or Temperature
boundary conditions for Thermal (steady-state and transient heat transfer) analysis or electric potential
for Electrical analysis.
Bulk Data Entry This entry can be used to define enforced displacement value for Static Analysis or enforced displacement, velocity,
or acceleration for Dynamic Analysis or enforced temperature for Thermal (steady-state and transient heat transfer)
Analysis or enforced electric potential for Electrical Analysis.
Bulk Data Entry Defines a surface spline for interpolating motion and forces for aeroelastic problems on aerodynamic geometries defined
by regular arrays of aerodynamic points.
Bulk Data Entry Defines a beam spline for interpolating motion and/or forces for aeroelastic problems on aerodynamic geometries defined
by regular arrays of aerodynamic points.
Bulk Data Entry Defines a tabular function for use in generating frequency-dependent and time-dependent dynamic loads. Also contains
parametric data for use with the table.
Bulk Data Entry Defines a tabular function for use in generating frequency-dependent and time-dependent dynamic loads. Also contains
parametric data for use with the table.
Bulk Data Entry Defines the coefficients of a power series for use in generating frequency-dependent and time-dependent dynamic loads.
Also contains parametric data for use with the table.
Bulk Data Entry Defines a tabular function for use in generating temperature-dependent material properties. Also contains parametric
data for use with the table.
Bulk Data Entry Defines a tabular function for use in generating temperature-dependent material properties. Also contains parametric
data for use with the table.
Bulk Data Entry Defines coefficients of a power series for use in generating temperature-dependent material properties. Also contains
parametric data for use with the table.
Bulk Data Entry Defines temperature field for shell elements (as a combination of reference plane temperature and linear thermal gradient
through thickness) for determination of thermal loading, temperature-dependent material properties and stress
recovery.
Bulk Data Entry Defines parameters for mapping the grid temperature field from either an external file or an internal heat transfer
subcase to Nonlinear Static Analysis. The mapping is over time-domain only.
Bulk Data Entry Defines values for the initial conditions of variables used in structural transient analysis and explicit analysis.
Both displacement and velocity values may be specified at independent degrees-of-freedom.
Bulk Data Entry Defines the unbalanced rotating load during a rotor dynamic analysis in Modal Frequency Response, Linear Direct Transient
or Small Displacement Nonlinear Direct Transient solution sequences. The unbalanced load is specified in a
cylindrical system where the rotor rotation axis is the Z-axis.
In order to prevent analyses from being carried out on badly discretized models, an element quality check
is incorporated into the pre-processing phase.
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).
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.
Element identification numbers within a
section definition must be unique with respect to all other element
identification numbers within the same section definition.
Grid points G1 through
G8 must be numbered as shown here:
This entry is only valid when it appears
between the BEGIN and END
statements.