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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
Bulk Data Section
Alphabetical listing of the Bulk Data Entries.
PARAM
Bulk Data Entry Defines values for parameters used during analysis and optimization.
PARAM, HEX8ALT
Bulk Data Entry Controls an alternative formulation of 8-noded CHEXA element for linear 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.
  - Subcase Information Section
    Alphabetical listing of the Subcase Information Entries.
  - Bulk Data Section
    Alphabetical listing of the Bulk Data Entries.
    - ACCEL
      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.
    - ACCEL1
      Bulk Data Entry Defines static acceleration loads at specific GRID points in the model.
    - ACCEL2
      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.
    - ACMODL
      Bulk Data Entry Defines model parameters for the fluid-structure interface.
    - ACSRCE
      Bulk Data Entry Defines acoustic source as a function of power versus frequency.
    - AECOMP
      Bulk Data Entry Defines a component for use in monitoring point definition or external splines.
    - AECOMPL
      Bulk Data Entry Defines a component for use in monitoring point definition or external splines.
    - AEFACT
      Bulk Data Entry Defines real numbers for Aeroelastic Analysis.
    - AELINK
      Bulk Data Entry Defines relationships between on among AESTAT and AESURF entries.
    - AELIST
      Bulk Data Entry Defines a list of aerodynamic box IDs.
    - AERO
      Bulk Data Entry Defines basic parameters for dynamic aeroelasticity.
    - AEROS
      Bulk Data Entry Defines basic parameters for static aeroelasticity.
    - AESTAT
      Bulk Data Entry Specifies rigid body motions to be used as trim variables in static aeroelasticity.
    - AESURF
      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).
    - ASET
      Bulk Data Entry Defines the boundary degrees-of-freedom of a superelement assembly for matrix reduction.
    - ASET1
      Bulk Data Entry Defines the boundary degrees-of-freedom of a superelement assembly for matrix reduction.
    - BASELIN
      Bulk Data Entry Corrects the acceleration record to avoid displacement shift.
    - BEGIN
      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.
    - BLKHDF
      Bulk Data Entry Defines the blank holder force in a one-step stamping simulation.
    - BMFACE
      Bulk Data Entry Defines quad or tria faces that are in turn used to define a barrier to limit the total deformation for free-shape design regions.
    - BNDFIX
      Bulk Data Entry Defines the degrees-of-freedom to be fixed during DMIG generation using CMSMETH card.
    - BNDFIX1
      Bulk Data Entry Defines the fixed (B-set) degrees-of-freedom to be fixed during DMIG generation using CMSMETH card.
    - BNDFRE1
      Bulk Data Entry Defines the free (C-set) degrees-of-freedom to be fixed during DMIG generation using CMSMETH card.
    - BNDFREE
      Bulk Data Entry Defines the degrees-of-freedom to be free during DMIG generation using CMSMETH card.
    - BORE
      Bulk Data Entry Defines the surface, coordinate system, and parameters required to request Bore Deformation output for Static Analysis Subcases.
    - BSET
      Bulk Data Entry Boundary Degrees-of-Freedom of a Superelement Assembly.
    - BSET1
      Bulk Data Entry Fixed Boundary Degrees-of-Freedom of a Superelement Assembly.
    - CAABSF
      Bulk Data Entry Defines the frequency-dependent fluid acoustic absorber element in coupled fluid-structural analysis.
    - CACINF3
      Bulk Data Entry Defines an Acoustic Infinite Element with a triangular base.
    - CACINF4
      Bulk Data Entry Defines an Acoustic Infinite Element with a quadrilateral base.
    - CACONV
      Bulk Data Entry Defines an interface for forced convection heat transfer using CAFLUID.
    - CACPML3
      Bulk Data Entry Defines an acoustic Adaptive Perfectly Matched Layer (APML) element with a triangular base.
    - CACPML4
      Bulk Data Entry Defines an acoustic Adaptive Perfectly Matched Layer (APML) element with a quadrilateral base.
    - CAERO1
      Bulk Data Entry Defines an aerodynamic macro element (panel) for lifting bodies 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.
    - CAERO2
      Bulk Data Entry Defines aerodynamic slender body and interference elements for Doublet-Lattice aerodynamics.
    - CAFLUID
      Bulk Data Entry Defines a 1D element that can conduct heat and transmit fluid between its two primary nodes.
    - CBAR
      Bulk Data Entry Defines a simple beam element (BAR) of the structural model.
    - CBEAM
      Bulk Data Entry Defines a beam element (BEAM) of the structural model.
    - CBUSH
      Bulk Data Entry Defines a generalized spring-damper structural element.
    - CBUSH1D
      Bulk Data Entry Defines a one-dimensional spring-damper structural element.
    - CDAMP1
      Bulk Data Entry Defines a scalar damper element.
    - CDAMP2
      Bulk Data Entry Defines a scalar damper element without reference to a property entry.
    - CDAMP3
      Bulk Data Entry Defines a scalar damper element that is connected only to scalar points.
    - CDAMP4
      Bulk Data Entry Defines a scalar damper element that is connected only to scalar points and is without reference to a material or property entry.
    - CDENST4
      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.
    - CDSMETH
      Bulk Data Entry Can be used in the component dynamic synthesis method for generating component dynamic matrices at each loading frequency.
    - CELAS1
      Bulk Data Entry Defines a scalar spring element of the structural model.
    - CELAS2
      Bulk Data Entry Defines a scalar spring element of the structural model without reference to a property entry.
    - CELAS2F
      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.
    - CELAS3
      Bulk Data Entry Defines a scalar spring element that connects only to scalar points.
    - CELAS4
      Bulk Data Entry Defines a scalar spring element that is connected only to scalar points without reference to a property entry.
    - CELAS4F
      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.
    - CELL
      Bulk Data Entry Defines a unit cell comprised of lattice entities which can be used for space filling via the DLATTICE entry.
    - CFAST
      Bulk Data Entry Define a fastener with material orientation connecting two shell surfaces.
    - CFASTG
      Bulk Data Entry Defines a fastener which can be used to model connections such as spot welds, rivets, bolts and so on.
    - CGAP
      Bulk Data Entry Defines a gap or friction element.
    - CGAPG
      Bulk Data Entry Defines a node-to-obstacle gap element. The obstacle may be an element face or a patch of nodes.
    - CGASK6
      Bulk Data Entry Defines the connections of the GASK6 solid gasket element.
    - CGASK8
      Bulk Data Entry Defines the connections of the GASK8 solid gasket element.
    - CGASK12
      Bulk Data Entry Defines the connections of the GASK12 solid gasket element.
    - CGASK16
      Bulk Data Entry Defines the connections of the GASK16 solid gasket element.
    - CHACAB
      Bulk Data Entry Defines the acoustic absorber element in coupled fluid-structural analysis.
    - CHARGE
      Bulk Data Entry Defines a point electric charge at a grid or a set of grids.
    - CHBDYE
      Bulk Data Entry Defines a surface element for application of thermal boundary condition.
    - CHEXA
      Bulk Data Entry Defines the connections of the HEXA solid element.
    - CHGAREA
      Bulk Data Entry Defines the charge density on faces of CHEXA, CPENTA, CTETRA, or CPYRA solid elements.
    - CHGVOL
      Bulk Data Entry Defines the charge density on a volume of CHEXA, CPENTA, CTETRA, or CPYRA solid elements.
    - CIFHEX
      Bulk Data Entry Defines the connections of the cohesive element.
    - CIFPEN
      Bulk Data Entry Defines the connections of the cohesive element.
    - CLRNC
      Bulk Data Entry Defines parameters for clearance and threaded bolts geometry.
    - CMASS1
      Bulk Data Entry Defines a scalar mass element.
    - CMASS2
      Bulk Data Entry Defines a scalar mass element without reference to a property entry.
    - CMASS3
      Bulk Data Entry Defines a scalar mass element that is connected only to scalar points.
    - CMASS4
      Bulk Data Entry Defines a scalar mass element that is connected only to scalar points, without reference to a property entry.
    - CMBEAM
      Bulk Data Entry Defines a beam element for multibody dynamics solution sequence without reference to a property entry.
    - CMBEAMM
      Bulk Data Entry Defines a beam element for multibody dynamic solution sequence without reference to a property entry based on markers.
    - CMBUSH
      Bulk Data Entry Defines a bushing element without reference to a property entry.
    - CMBUSHC
      Bulk Data Entry Defines a bushing element without reference to a property entry.
    - CMBUSHE
      Bulk Data Entry Defines a bushing element without reference to a property entry.
    - CMBUSHM
      Bulk Data Entry Defines a bushing element without reference to a property entry based on markers.
    - CMBUSHT
      Bulk Data Entry Defines a bushing element without reference to a property entry.
    - CMSMETH
      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.
    - CMSPDP
      Bulk Data Entry Defines a spring damper element without reference to a property entry for multibody solution sequence.
    - CMSPDPC
      Bulk Data Entry Defines a spring damper element without reference to a property entry for multibody solution sequence.
    - CMSPDPE
      Bulk Data Entry Defines a spring damper element without reference to a property entry for multibody solution sequence.
    - CMSPDPM
      Bulk Data Entry Defines a spring damper element without reference to a property entry for multibody solution sequence based on marker.
    - CMSPDPT
      Bulk Data Entry Defines a spring damper element without reference to a property entry for multibody solution sequence.
    - CNTITF
      Bulk Data Entry Defines parameters for contact (S2S and N2S) interference.
    - CNTLCK
      Bulk Data Entry Defines parameters for the contact (S2S and N2S) lock in the preloaded Linear Analysis subcase.
    - CNTSTB
      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.
    - CNVGADD
      Bulk Data Entry Allows referencing a combined free convection definition via multiple CONVG Bulk Data Entries.
    - CONM1
      Bulk Data Entry Defines a 6x6 mass matrix at a geometric grid point.
    - CONM2
      Bulk Data Entry Defines a concentrated mass at a grid point of the structural model.
    - CONNECT
      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.
    - CONROD
      Bulk Data Entry Defines a rod element without reference to a property entry.
    - CONTACT
      Bulk Data Entry Defines a contact interface.
    - CONTPRM
      Bulk Data Entry Defines the default properties of all contacts and sets parameters that affect all contacts.
    - CONV
      Bulk Data Entry Defines a free convection boundary condition for heat transfer analysis through connection to a surface element (CHBDYE card).
    - CONVG
      Bulk Data Entry Defines Free convection via automatic generation of free convection entries. This entry also supports subcase-dependent free convection.
    - CORD1C
      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.
    - CORD1R
      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.
    - CORD1S
      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.
    - CORD2C
      Bulk Data Entry Defines a cylindrical coordinate system using three grid points specified with respect to a reference coordinate system.
    - CORD2R
      Bulk Data Entry Defines a rectangular coordinate system by using three grid points.
    - CORD2S
      Bulk Data Entry Defines a spherical coordinate system three grid points.
    - CORD3R
      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.
    - CORD4R
      Bulk Data Entry Defines a rectangular coordinate system using three grid points specified with respect to the basic coordinate system.
    - COUPLER
      Bulk Data Entry Defines a coupler connecting two or three joints.
    - CPENTA
      Bulk Data Entry Defines the connections of the CPENTA element.
    - CPYRA
      Bulk Data Entry Defines the connections of the PYRA solid element.
    - CQAXI
      Bulk Data Entry Defines a 2D axisymmetric quadrilateral cross-section ring element.
    - CQAXIG
      Bulk Data Entry Defines a quadrilateral cross-section general axisymmetric element that allows circumferential deformation.
    - CQPSTN
      Bulk Data Entry Defines a plane strain quadrilateral element in x-z or x-y plane.
    - CQPSTS
      Bulk Data Entry Plane stress quadrilateral element connection. Defines a plane stress quadrilateral element in the x-z or x-y plane.
    - CQUAD4
      Bulk Data Entry Defines a quadrilateral plate element (QUAD4) of the structural model. This element uses a 6 degree-of-freedom per node formulation.
    - CQUAD8
      Bulk Data Entry Defines a curved quadrilateral shell element with eight grid points.
    - CQUADR
      Bulk Data Entry Equivalent to CQUAD4. Unlike other Nastran codes, a 6 degree-of-freedom per node formulation is used for all shell elements.
    - CROD
      Bulk Data Entry Defines a tension-compression-torsion element (ROD) of the structural model.
    - CSEAM
      Bulk Data Entry Defines a seam weld connecting two shell surfaces.
    - CSEC2
      Bulk Data Entry Defines a two-noded element used in the definition of arbitrary beam cross-sections.
    - CSEC3
      Bulk Data Entry Defines a 1st order, three-noded element used in the definition of arbitrary beam cross-sections.
    - CSEC4
      Bulk Data Entry Defines a 1st order, four-noded element used in the definition of arbitrary beam cross-sections.
    - CSEC6
      Bulk Data Entry Defines a planar, 2nd order, six-noded element used in the definition of arbitrary beam cross-sections.
    - CSEC8
      Bulk Data Entry Defines a planar 2nd order, eight-noded element used in the definition of arbitrary beam cross-sections.
    - CSET
      Bulk Data Entry Boundary Degrees-of-Freedom of a Superelement Assembly.
    - CSET1
      Bulk Data Entry Boundary Degrees-of-Freedom of a Superelement Assembly.
    - CSHEAR
      Bulk Data Entry Defines a shear panel element.
    - CSUPEXT
      Bulk Data Entry Defines the Exterior grid points for One-Step Superelement Analysis.
    - CTAXI
      Bulk Data Entry Defines an axisymmetric triangular cross-section ring element.
    - CTAXIG
      Bulk Data Entry Defines a triangular cross-section general axisymmetric element that allows circumferential deformation.
    - CTETRA
      Bulk Data Entry Defines the connections of the CTETRA element.
    - CTPSTN
      Bulk Data Entry Defines a plane strain triangular element in x-z or x-y plane.
    - CTPSTS
      Bulk Data Entry Plane stress triangular element connection. Defines a plane stress triangular element in the x-z or x-y plane.
    - CTRIA3
      Bulk Data Entry Defines a triangular plate element (TRIA3) of the structural model. This element uses a 6 degree-of-freedom per node formulation.
    - CTRIA6
      Bulk Data Entry Defines a curved triangular shell element with six grid points.
    - CTRIAR
      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.
    - CTRIAX6
      Bulk Data Entry Defines an axisymmetric triangular cross-section ring element.
    - CTUBE
      Bulk Data Entry Defines a tension-compression-torsion element (TUBE) of the structural model.
    - CURRENT
      Bulk Data Entry Defines a static point current at a grid or a set of grids, by specifying a vector, in Electrical analysis.
    - CVISC
      Bulk Data Entry Defines a viscous damper element.
    - CWELD
      Bulk Data Entry Defines a weld or fastener connecting two surface patches or points.
    - CYAX
      Bulk Data Entry Used to list the grids that lie on the axis of symmetry, in cyclic symmetry analysis.
    - CYJOIN
      Bulk Data Entry Defines points on one of the boundaries that connect to adjacent segments in cyclic symmetry analysis.
    - CYSYM
      Bulk Data Entry Specifies the number of segments, in a cyclic symmetry analysis.
    - DAREA
      Bulk Data Entry Defines scale (area) factors for dynamic loads. DAREA is used in conjunction with RLOAD1, RLOAD2, TLOAD1, and TLOAD2 entries.
    - DCOMP
      Bulk Data Entry Defines manufacturing constraints for composite sizing optimization.
    - DCONADD
      Bulk Data Entry Creates a combination of several DCONSTR sets that can be referenced by a subcase.
    - DCONSTR
      Bulk Data Entry Defines design constraint upper and lower bounds where response is defined by DRESP1, DRESP2, and DRESP3 cards.
    - DDVAL
      Bulk Data Entry Define real, discrete design variable values for discrete variable optimization or to define relative rotor spin rates in rotor dynamics.
    - DEFORM
      Bulk Data Entry Defines enforced axial deformation for one-dimensional elements for use in statics problems.
    - DELAY
      Bulk Data Entry Defines the time delay term $τ$ in the equations of the dynamic loading function. DELAY is used in conjunction with RLOAD1, RLOAD2, TLOAD1, and TLOAD2 entries.
    - DEQATN
      Bulk Data Entry Specifies one or more equations for use in optimization.
    - DESVAR
      Bulk Data Entry Defines a design variable.
    - DESVARG
      Bulk Data Entry Defines an override for design variable settings.
    - DGLOBAL
      Bulk Data Entry Defines input parameters required for the Global Search Option (GSO).
    - DIM
      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.
    - DIVERG
      Bulk Data Entry Specifies the number of Divergence pressures and Mach numbers for a static aeroelastic divergence analysis.
    - DLATTICE
      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.
    - DLINK
      Bulk Data Entry Defines a link between one design variable and one or more other design variables.
    - DLINK1
      Bulk Data Entry Defines a link between one design variable and one or more other design variables.
    - DLINK2
      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.
    - DLOAD
      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.
    - DMGEVO
      Bulk Data Entry Defines the damage evolution.
    - DMGINI
      Bulk Data Entry Defines the damage initiation criteria.
    - DMI
      Bulk Data Entry Defines matrix (real) data blocks for Aeroelastic Analysis.
    - DMIG
      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.
    - DMIGMOD
      Bulk Data Entry Defines changes in the contents of a super element from H3DDMIG input.
    - DMIGROT
      Bulk Data Entry Controls rotation and other specifications for a matrix entered using DMIG entry.
    - DOBJREF
      Bulk Data Entry Defines a response and its reference values for a minmax (maxmin) optimization problem.
    - DOPTPRM
      Bulk Data Entry Defines design optimization parameters by overriding the defaults.
    - DPHASE
      Bulk Data Entry Defines the phase lead term $θ$ in the equation of the dynamic loading function. DPHASE is used in conjunction with RLOAD1 and RLOAD2 entries.
    - DRAPE
      Bulk Data Entry Defines the draping data for plies used in ply-based composite definition.
    - DREPADD
      Bulk Data Entry Creates a combination of several DREPORT sets that can be referenced by a subcase.
    - DREPORT
      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.
    - DRESP1
      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.
    - DRESP2
      Bulk Data Entry When a desired response is not directly available from OptiStruct, it may be calculated using DRESP2.
    - DRESP3
      Bulk Data Entry The DRESP3 card identifies the external function to be called and defines the parameters to be transferred to that function.
    - DSCREEN
      Bulk Data Entry Defines design response screening data.
    - DSHAPE
      Bulk Data Entry Defines parameters for classic and grid-based free-shape design variables.
    - DSHUFFLE
      Bulk Data Entry Defines parameters for the generation of composite shuffling design variables.
    - DSIZE
      Bulk Data Entry Defines parameters for the generation of free-size design variables.
    - DSYSID
      Bulk Data Entry Defines responses and their target values for a system identification problem.
    - DTABLE
      Bulk Data Entry List of constants to be used in functions defined by DEQATN.
    - DTI,SPECSEL
      Bulk Data Entry Correlates spectra lines specified on TABLED1 entries with damping values.
    - DTI,UNITS
      Bulk Data Entry Defines units for multibody, component mode synthesis (flexible-body preparation), and Explicit Dynamic Analysis sequences.
    - DTPG
      Bulk Data Entry Defines parameters for the generation of topography design variables.
    - DTPL
      Bulk Data Entry Defines parameters for the generation of topology design variables.
    - DTRUSS
      Bulk Data Entry Activates Truss Layout Optimization and defines the corresponding parameters for design optimization, including truss cross-sectional area limits, stress, symmetry, and buckling constraints.
    - DVCREL1
      Bulk Data Entry Relates Design Variables to Analysis Model Element Properties
    - DVCREL2
      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.
    - DVCREL - Types
    - DVGRID
      Bulk Data Entry Defines the relationship between a design variable and a grid point location.
    - DVLREL1
      Bulk Data Entry Linearly relates a design variable to an analysis model element.
    - DVLREL2
      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.
    - DVMBRL1
      Bulk Data Entry Linearly relates a design variable to properties of an MBD entity using the equation: $P_{i} = C 0 + \sum {COEF}_{i} * {DVID}_{i}$
    - DVMBRL2
      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.
    - DVMREL1
      Bulk Data Entry Linearly relates a design variable to an analysis model material property using the equation: ${MP}_{i} = C_{0} + \sum_{i} {COEF}_{i} \cdot {DVID}_{i}$
    - DVMREL2
      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.
    - DVMREL - Types
    - DVPREL1
      Bulk Data Entry Relates Design Variables to Analysis Model Properties
    - DVPREL2
      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.
    - DVPREL - Types
    - EDEM
      Bulk Data Entry Defines the parameters required to activate coupling between OptiStruct and EDEM.
    - EDGEBH
      Bulk Data Entry Defines geometry and restraining force per unit length for an edge blank holder in a one-step stamping simulation.
    - EDRAWB
      Bulk Data Entry Defines location and restraining force per unit length for a draw bead in a one-step stamping simulation.
    - EIGC
      Bulk Data Entry Defines data required to perform complex eigenvalue analysis.
    - EIGRA
      Bulk Data Entry Defines the data required to perform real eigenvalue analysis with the Automated Multi-Level Sub-structuring technique.
    - EIGRD
      Bulk Data Entry Defines data required to perform eigenvalue extraction using the Lapack-based dense solver.
    - EIGRL
      Bulk Data Entry Defines data required to perform real eigenvalue analysis (vibration or buckling) with the Lanczos method.
    - EL2MAT
      Bulk Data Entry Used to assign material ID to elements.
    - EL2PROP
      Bulk Data Entry Used to assign property ID to elements in DMIG.
    - ELEMQUAL
      Bulk Data Entry Resets the default values of the warning and error bound limits for element quality check.
    - ELIST
      Bulk Data Entry Specifies damp shell elements for a fluid volume. ELIST entries are referenced by the MFLUID entry.
    - END
      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.
    - ERPPNL
      Bulk Data Entry Defines one or more sets of elements as panels for equivalent radiated power output for a frequency response analysis.
    - ESLTADD
      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.
    - ESLTIME
      Bulk Data Entry Defines time step selection control for geometric nonlinear response ESL Optimization and Multibody dynamics ESLM optimization.
    - EXTRN
      Bulk Data Entry Defines boundary connections for an external superelement.
    - FATDEF
      Bulk Data Entry Defines elements or grids, and associated fatigue properties, for consideration in a fatigue analysis.
    - FATEVNT
      Bulk Data Entry Defines loading events for Fatigue Analysis.
    - FATLOAD
      Bulk Data Entry Defines fatigue loading parameters.
    - FATPARM
      Bulk Data Entry Used to define parameters required for a Fatigue Analysis.
    - FATSDR
      Bulk Data Entry Defines the solder joint for consideration in solder fatigue analysis.
    - FATSEAM
      Bulk Data Entry Used to define parameters and property identification data for Seam Weld Fatigue Analysis.
    - FATSEQ
      Bulk Data Entry Defines a loading sequence for a Fatigue Analysis.
    - FLDATA
      Bulk Data Entry Defines a forming limit curve as a table of minor and major strain values in a one-step stamping simulation.
    - FLFACT
      Bulk Data Entry Used to specify the aerodynamic factors in aerodynamic flutter analysis.
    - FLLWER
      Bulk Data Entry Defines parameters for the calculation follower loads in large displacement nonlinear analysis.
    - FLUTTER
      Bulk Data Entry Used to specify the parameters required for aerodynamic flutter analysis.
    - FORCE
      Bulk Data Entry Defines a static force at a grid point or a SET of grid points by specifying a vector.
    - FORCE1
      Bulk Data Entry Used to define a static force by specification of a value and two grid points that determine the direction.
    - FORCE2
      Bulk Data Entry Used to define a static force by specification of a value and four grid points that determine the direction.
    - FREQ
      Bulk Data Entry Defines a set of frequencies to be used in the solution of frequency response problems.
    - FREQ1
      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.
    - FREQ2
      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.
    - FREQ3
      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.
    - FREQ4
      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.
    - FREQ5
      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.
    - FSI
      Bulk Data Entry Defines the settings for Fluid-Structure Interaction Analysis with AcuSolve.
    - GAPPRM
      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.
    - GENEL
      Bulk Data Entry Defines the stiffness, flexibility, mass, viscous damping, or structural damping of a general element connected to an arbitrary number of grids.
    - GMATCH
      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.
    - GRAV
      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.
    - GRDSET
      Bulk Data Entry Defines default options for fields 3, 7, and 8 of all GRID entries.
    - GRID
      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 or permanent zero electric potential.
    - GRIDS
      Bulk Data Entry Defines a grid point on the y-z plane, using cartesian coordinates, for use in the definition of arbitrary beam cross-sections.
    - GROUND
      Bulk Data Entry Defines a ground body out of a list of finite element properties, elements, and grid points.
    - HOURGLS
      Bulk Data Entry Defines hourglass control parameters to reduce spurious zero-energy modes in elements with reduced integration.
    - HYBDAMP
      Bulk Data Entry Defines the application of modal damping to the residual structure in a Direct Transient or Frequency Response analysis.
    - IMPERF
      Bulk Data Entry Define the initial geometric imperfection at the beginning of a nonlinear analysis.
    - INCLUDE
      Bulk Data Entry This Bulk Data card is identical to the I/O Options Entry, INCLUDE.
    - INIPS
      Bulk Data Entry Defines initial plastic strain values and settings for elements in nonlinear analysis.
    - INISTRS
      Bulk Data Entry Defines initial stress values and settings for elements in nonlinear analysis.
    - INLTVEL
      Bulk Data Entry Defines the Inlet velocity for Darcy Flow Analysis.
    - INSTNCE
      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.
    - INVELB
      Bulk Data Entry Defines initial velocity in a multibody situation.
    - INVELJ
      Bulk Data Entry Defines initial velocity of a joint in a multibody situation.
    - IPSADD
      Bulk Data Entry Defines initial plastic strain condition for nonlinear static analysis as a union of INIPS entries.
    - ISTSADD
      Bulk Data Entry Defines initial stress condition for nonlinear quasi-static analysis as a union of INISTRS entries.
    - JOINT
      Bulk Data Entry Defines a joint for Multibody Dynamics.
    - JOINTG
      Bulk Data Entry Defines a joint connection between two grids.
    - JOINTM
      Bulk Data Entry Defines a joint using two grids which have a marker card associated with them. Joints are only valid in a multibody solution sequence.
    - LATPRM
      Bulk Data Entry Defines the parameters available for Lattice Optimization Control.
    - LOAD
      Bulk Data Entry The LOAD is equivalent to the LOADADD.
    - LOADADD
      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.
    - LOADCYH
      Bulk Data Entry Used to define the loading by harmonics in cyclic symmetry analysis.
    - LOADCYN
      Bulk Data Entry Used to define the loading by segments in cyclic symmetry analysis.
    - LOADJG
      Bulk Data Entry Defines loading for joint connector JOINTG Bulk Data Entry.
    - LOCATE
      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.
    - MAP
      Bulk Data Entry Used to map results to the model (OptiStruct) from other external result files.
    - MARKER
      Bulk Data Entry Define a marker by associating a grid and a coordinate system.
    - MASSSET
      Bulk Data Entry Defines a linear combination of mass cases to form the subcase dependent mass.
    - MAT1
      Bulk Data Entry Defines the material properties for linear, temperature-independent, and isotropic materials.
    - MAT1EC
      Bulk Data Entry Defines constant electrical material properties for resistivity and Joule heat fraction in electrical analysis.
    - MAT1PT
      Bulk Data Entry Defines isotropic permittivity and damping for dielectric materials.
    - MAT2
      Bulk Data Entry Defines the material properties for linear, temperature-independent, and anisotropic materials for two-dimensional elements.
    - MAT2EC
      Bulk Data Entry Defines the electrical material properties for anisotropic materials in electrical analysis.
    - MAT2PT
      Bulk Data Entry Defines anisotropic permittivity and damping for dielectric materials
    - MAT3
      Bulk Data Entry Defines the material properties for linear, temperature-independent, and orthotropic materials used by the CTAXI, CTRIAX6, CQAXI, CTAXIG, and CQAXIG axisymmetric elements, and CTPSTN and CQPSTN plane strain elements.
    - MAT4
      Bulk Data Entry Defines constant thermal material properties for conductivity, density, and heat generation.
    - MAT5
      Bulk Data Entry Defines the thermal material properties for anisotropic materials.
    - MAT8
      Bulk Data Entry Defines the material properties for linear temperature-independent orthotropic material for two-dimensional elements.
    - MAT9
      Bulk Data Entry Defines the material properties for linear, temperature-independent, and anisotropic materials for solid elements.
    - MAT9OR
      Bulk Data Entry Defines the material properties for linear, temperature-independent, and orthotropic materials for solid elements in terms of engineering constants.
    - MAT10
      Bulk Data Entry Defines material properties for fluid elements in coupled fluid-structural analysis.
    - MATBRT
      Bulk Data Entry Defines the material properties for Brittle Damage material models.
    - MATF
      Bulk Data Entry Defines material properties and failure model parameters for Failure criteria calculations.
    - MATFAT
      Bulk Data Entry Defines material properties for fatigue analysis.
    - MATFATT
      Bulk Data Entry Defined temperature-dependent material properties for fatigue analysis.
    - MATF1
      Bulk Data Entry Specifies frequency-dependent material properties on MAT1 entry fields via TABLEDi entries.
    - MATF2
      Bulk Data Entry Specifies frequency-dependent material properties on MAT2 entry fields via TABLEDi entries.
    - MATF3
      Bulk Data Entry Specifies frequency-dependent material properties on MAT3 entry fields via TABLEDi entries.
    - MATF8
      Bulk Data Entry Specifies frequency-dependent material properties on MAT8 entry fields via TABLEDi entries.
    - MATF9
      Bulk Data Entry Specifies frequency-dependent material properties on MAT9 entry fields via TABLEDi entries.
    - MATF10
      Bulk Data Entry Specifies frequency-dependent material properties on MAT10 entry fields via TABLEDi entries.
    - MATFVE
      Bulk Data Entry Defines material properties for frequency-dependent viscoelastic materials.
    - MATHCOMB
      Bulk Data Entry This material data defines honeycomb material behavior in Explicit analysis.
    - MATHE
      Bulk Data Entry Defines material properties for nonlinear hyperelastic materials. The Polynomial form is available and various material types topics/solvers/os/mathe_bulk_r.html#mathe_bulk_r__mathe_bulk_r_fn_jgc_4dt_b1b can be defined by specifying the corresponding coefficients.
    - MATHF
      Bulk Data Entry Defines the material properties in a one-step stamping simulation.
    - MATMDS
      Bulk Data Entry Defines material properties and parameters through an interface to Altair Multiscale Designer® allowing you to include a much wider range of different material models.
    - MATPE1
      Bulk Data Entry Defines the material properties for poro-elastic materials.
    - MATPZO
      Bulk Data Entry Defines the coupling terms between structural and dielectric materials for defining a piezoelectric coupling.
    - MATS1
      Bulk Data Entry Specifies strain-, rate-, and temperature-dependent material properties for use in applications involving nonlinear materials.
    - MATT1
      Bulk Data Entry Specifies temperature-dependent material properties on MAT1 entry fields via TABLEMi or TABLEG entry.
    - MATT1EC
      Bulk Data Entry Defines temperature-dependent material properties for the corresponding MAT1EC Bulk Data Entry fields via TABLEMi or TABLEG entries.
    - MATT1PT
      Bulk Data Entry Defines temperature-dependent isotropic permittivity via the TABLEM1-4 or TABLEG Bulk Data Entries for dielectric materials.
    - MATT2
      Bulk Data Entry Specifies temperature-dependent material properties on MAT2 entry fields via TABLEMi or TABLEG entry.
    - MATT2EC
      Bulk Data Entry Defines temperature-dependent material properties for the corresponding MAT2EC Bulk Data Entry fields via TABLEMi or TABLEG entries.
    - MATT2PT
      Bulk Data Entry Defines temperature-dependent anisotropic permittivity via the TABLEM1-4 or TABLEG Bulk Data Entries for dielectric materials.
    - MATT3
      Bulk Data Entry Specifies temperature-dependent material properties on MAT3 entry fields via TABLEMi or TABLEG entry.
    - MATT4
      Bulk Data Entry Defines temperature-dependent material properties for the corresponding MAT4 Bulk Data Entry fields via TABLEMi or TABLEG entry.
    - MATT8
      Bulk Data Entry Specifies temperature-dependent material properties on MAT8 entry fields via TABLEMi or TABLEG entry.
    - MATT9
      Bulk Data Entry Specifies temperature-dependent material properties on MAT9 entry fields via TABLEMk or TABLEG entry.
    - MATT9OR
      Bulk Data Entry Specifies temperature-dependent material properties on MAT9OR entry fields via TABLEMk or TABLEG entry.
    - MATTHE
      Bulk Data Entry Defines material properties for temperature-dependent nonlinear hyperelastic materials.
    - MATTPZO
      Bulk Data Entry Defines temperature-dependent coupling terms between structural and dielectric materials, for defining a piezoelectric coupling.
    - MATTVE
      Bulk Data Entry Defines material properties for temperature-dependent nonlinear viscoelastic materials.
    - MATTVP
      Bulk Data Entry Defines temperature-dependent material properties for the corresponding MATVP Bulk Data Entry fields via TABLEMi or TABLEG entry.
    - MATUSHT
      Bulk Data Entry Defines thermal material properties and parameters for user-defined thermal material.
    - MATUSR
      Bulk Data Entry Defines material properties and parameters for user-defined structural material.
    - MATVE
      Bulk Data Entry Defines material properties for nonlinear viscoelastic materials.
    - MATVP
      Bulk Data Entry Defines material properties for nonlinear creep materials.
    - MBACT
      Bulk Data Entry Defines the entity/set that needs to be activated in the multibody system for the subsequent simulation.
    - MBCNTDS
      Bulk Data Entry Defines a Multibody Contact between a set of nodes and a deformable surface.
    - MBCNTR
      Bulk Data Entry Defines a Multibody contact between rigid bodies.
    - MBCRV
      Bulk Data Entry Specifies the data used to define a curve.
    - MBCVCV
      Bulk Data Entry Defines a Curve to Curve Constraint.
    - MBDCRV
      Bulk Data Entry Defines an ordered list of grids as a Multibody Deformable Curve.
    - MBDEACT
      Bulk Data Entry Defines the entity/set that needs to be deactivated in the multibody system for the subsequent simulation.
    - MBDSRF
      Bulk Data Entry Defines a multibody deformable surface.
    - MBFRC
      Bulk Data Entry Defines a constant force at a grid point by specifying a vector.
    - MBFRCC
      Bulk Data Entry Defines a curve force at a grid point by specifying a vector.
    - MBFRCE
      Bulk Data Entry Defines an expression force at a grid point by specifying a vector.
    - MBLIN
      Bulk Data Entry Defines the parameters for a multibody system linear analysis.
    - MBMNT
      Bulk Data Entry Defines a constant moment at a grid point by specifying a vector.
    - MBMNTC
      Bulk Data Entry Defines a curve moment at a grid point by specifying a vector.
    - MBMNTE
      Bulk Data Entry Defines an expression moment at a grid point by specifying a vector.
    - MBPCRV
      Bulk Data Entry Defines a Multibody Parametric Curve using node sets.
    - MBPTCV
      Bulk Data Entry Defines a Point to Parametric Curve Constraint.
    - MBPTDCV
      Bulk Data Entry Defines a Point to Deformable Curve Constraint.
    - MBPTDSF
      Bulk Data Entry Defines a Point to Deformable Surface Constraint.
    - MBREQ
      Bulk Data Entry Defines a multibody as a combination of request sets defined via MBREQE and MBREQM.
    - MBREQE
      Bulk Data Entry Defines a multibody solver output request to output the results of a set of expressions.
    - MBREQM
      Bulk Data Entry Defines a multibody solver output request to output displacement, velocity, acceleration, or force with respect to markers.
    - MBSEQ
      Bulk Data Entry Defines the simulation sequence for the multibody solver.
    - MBSFRC
      Bulk Data Entry Defines a constant scalar load on two grid points.
    - MBSFRCC
      Bulk Data Entry Defines a curve scalar load on two grid points.
    - MBSFRCE
      Bulk Data Entry Defines an expression scalar load on two grid points.
    - MBSIM
      Bulk Data Entry Defines the parameters for a multibody simulation.
    - MBSIMP
      Bulk Data Entry Defines the simulation parameters for subsequent multibody simulation.
    - MBSMNT
      Bulk Data Entry Defines a constant scalar moment on two grid points along the specified vector.
    - MBSMNTC
      Bulk Data Entry Defines a curve scalar moment on two grid points along the specified vector.
    - MBSMNTE
      Bulk Data Entry Defines an expression scalar moment on two grid points along the specified vector.
    - MBVAR
      Bulk Data Entry Defines a multibody solver variable which can be referred to by multiple expressions.
    - MCIRON
      Bulk Data Entry Defining the material properties of cast iron material for use in applications involving nonlinear materials.
    - MCOHE
      Bulk Data Entry Defines the material properties for potential-based cohesive material models.
    - MCOHED
      Bulk Data Entry Defines the material properties for damage-based cohesive material models.
    - MEFFSET
      Bulk Data Entry This entry is used to group element sets for which MEFFMASS output is desired in HyperMesh set based format.
    - MESHF
      Bulk Data Entry Defines options for user-defined input of frequency ranges used to define bands in adaptive meshing for acoustic Adaptive Perfectly Matched Layer (APML) analysis.
    - METADATA
      Bulk Data Entry METADATA indicates the beginning of metadata content that is to be passed to the OUTPUT2 (.op2 file).
    - MFLUID
      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.
    - MGASK
      Bulk Data Entry Defining the material properties for gasket-like materials.
    - MKAERO1
      Bulk Data Entry To input a table of Mach numbers (M) and reduced frequencies (K) for aerodynamic matrix calculation, in unsteady aerodynamic analysis.
    - MKAERO2
      Bulk Data Entry To input a table of Mach number (M) and reduced frequency (K) pairs for aerodynamic matrix calculation, in unsteady aerodynamic analysis.
    - MLOAD
      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.
    - MODCHG
      Bulk Data Entry Defines parameters for removing and/or reactivating contact interfaces and/or elements.
    - MODOUT
      Bulk Data Entry Options for displacement and energy results, based on eigenvectors from PFMODE modal participation.
    - MODTRAK
      Bulk Data Entry Defines parameters for mode tracking in optimizations with eigenvalue analysis.
    - MOMENT
      Bulk Data Entry Defines a static moment at a grid point or a SET of grid points by specifying a vector.
    - MOMENT1
      Bulk Data Entry Defines a static moment by specification of a value and two grid points, which determines the direction.
    - MOMENT2
      Bulk Data Entry Defines a static moment by specification of a value and four grid points, which determines the direction.
    - MONPNT1
      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.
    - MONPNT2
      Bulk Data Entry Define an integrated load monitor point for specific elements and to output results for these elements.
    - MONPNT3
      Bulk Data Entry Sums select Grid Point Forces to a user chosen monitor point.
    - MONVOL
      Bulk Data Entry Defines a one-chamber gas filled structure with hybrid input of inflated gas.
    - MOTION
      Bulk Data Entry Defines a multibody as a combination of motion sets defined via MOTNJ, MOTNJC, MOTNJE, MOTNG, MOTNGC, and MOTNGE.
    - MOTNG
      Bulk Data Entry Defines a constant grid point motion.
    - MOTNGC
      Bulk Data Entry Defines a grid point motion versus time by specifying a curve.
    - MOTNGE
      Bulk Data Entry Defines a grid point motion through an expression.
    - MOTNJ
      Bulk Data Entry Defines a constant joint motion.
    - MOTNJC
      Bulk Data Entry Defines a joint motion versus time by specifying a curve.
    - MOTNJE
      Bulk Data Entry Defines a joint motion through an expression.
    - MOTNJG
      Bulk Data Entry Defines motion for joint connector JOINTG Bulk Data Entry.
    - MPC
      Bulk Data Entry The MPC Bulk Data Entry defines a multipoint constraint equation of the form.
    - MPCADD
      Bulk Data Entry Defines a multipoint constraint set as a union of multipoint constraint sets defined via MPC entries.
    - NLADAPT
      Bulk Data Entry Defines parameters for time-stepping and convergence criteria in Nonlinear Analysis.
    - NLCTRL
      Bulk Data Entry Uses keywords to define various control parameters for both Nonlinear Static and Nonlinear Transient Analysis.
    - NLENRG
      Bulk Data Entry Defines parameters for energy variables printout for implicit nonlinear static, implicit nonlinear transient analyses, explicit dynamic analysis, and linear static analysis (with Neuber correction).
    - NLMON
      Bulk Data Entry Defines the settings for runtime monitoring of nonlinear analysis.
    - NLOUT
      Bulk Data Entry Defines incremental result output parameters for Nonlinear Implicit Analysis (static and transient) and Nonlinear Explicit Analysis.
    - NLPARM
      Bulk Data Entry Defines parameters for Nonlinear Static Analysis, Nonlinear Transient Analysis, and Nonlinear Heat Transfer Analysis solution control.
    - NLPCI
      Bulk Data Entry Define the parameters for arc-length method to solve post-buckling problems in nonlinear static analysis.
    - NLPRINT
      Bulk Data Entry Controls the printing of certain information to the _nl.out file for nonlinear analysis.
    - NLRGAP
      Bulk Data Entry Defines a nonlinear radial (circular) gap for direct transient response analysis.
    - NOLIN1
      Bulk Data Entry Defines nonlinear transient forcing functions of the form.
    - NOLIN2
      Bulk Data Entry Defines nonlinear transient forcing functions of the form.
    - NOLIN3
      Bulk Data Entry Defines nonlinear transient forcing functions of the form.
    - NOLIN4
      Bulk Data Entry Defines nonlinear transient forcing functions of the form.
    - NSGE
      Bulk Data Entry Defines non-structural material damping for a list of elements or properties.
    - NSGE1
      Bulk Data Entry Defines non-structural material damping for a list of elements or properties.
    - NSGEADD
      Bulk Data Entry Defines non-structural material damping as the sum of the sets listed.
    - NSM
      Bulk Data Entry Defines non-structural mass per unit Length, per unit Area, or per unit Volume for a list of elements or properties.
    - NSM1
      Bulk Data Entry Defines non-structural mass per unit area or per unit length for a list of elements or properties.
    - NSMADD
      Bulk Data Entry Defines non-structural mass as the sum of the sets listed.
    - NSML
      Bulk Data Entry Defines lumped non-structural mass for a list of elements or properties.
    - NSML1
      Bulk Data Entry Defines lumped non-structural mass for a list of elements or properties.
    - PAABSF
      Bulk Data Entry Defines the properties of the fluid acoustic absorber element.
    - PACABS
      Bulk Data Entry Defines the properties of an acoustic absorber element.
    - PACINF
      Bulk Data Entry Defines the properties of Acoustic Infinite Elements.
    - PACPML
      Bulk Data Entry Defines the properties of acoustic Adaptive Perfectly Matched Layer (APML) elements.
    - PAERO1
      Bulk Data Entry Defines properties for lifting panels (CAERO1 panels) and also identifies the slender bodies (CAERO2 panels) associated/interacting with the lifting panels. This is used for Vortex Lattice Method (VLM) and Doublet Lattice Method (DLM) in subsonic aeroelastic analysis.
    - PAERO2
      Bulk Data Entry Defines the cross-sectional properties of slender bodies. This is used for Vortex Lattice Method (VLM) and Doublet Lattice Method (DLM) in subsonic aeroelastic analysis.
    - PAFLUID
      Bulk Data Entry Defines the properties of a 1D CAFLUID heat flow element.
    - PANEL
      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.
    - PANELG
      Bulk Data Entry Defines a set of grid points and/or elements as a generic panel.
    - PARAM
      Bulk Data Entry Defines values for parameters used during analysis and optimization.
      - Parameters by Function
        List of parameters according to parameter type.
      - PARAM, ACMODL12
        Bulk Data Entry Restores the ACMODL formulation used in version 12.0 and earlier for the Fluid-Structure Interface.
      - PARAM, ACMTXNO
        Bulk Data Entry This parameter sets preferences for storage of reduced fluid mass, fluid stiffness, and fluid damping matrices for acoustic superelements.
      - PARAM, ACPREFDB
        Bulk Data Entry Specifies the reference acoustic power value used to calculate Acoustic Power (ACPOWER) in decibels (dB).
      - PARAM, AGGPCH
        Bulk Data Entry To support output of the fluid-structure coupling matrix to the Punch (.pch) file as a matrix defined using DMIG data entry.
      - PARAM, AKUSMOD
        Bulk Data Entry Use external fluid-structure coupling matrix generated by AKUSMOD.
      - PARAM, ALLFT
        Bulk Data Entry This parameter is used to control the output from multiple failure theories to the H3D and .cstr files.
      - PARAM, ALPHA1
        Bulk Data Entry Adds Rayleigh damping to viscous damping for structural mesh.
      - PARAM, ALPHA1FL
        Bulk Data Entry Adds Rayleigh damping to viscous damping for fluid mesh.
      - PARAM, ALPHA2
        Bulk Data Entry Adds Rayleigh damping to viscous damping for structural mesh.
      - PARAM, ALPHA2FL
        Bulk Data Entry Adds Rayleigh damping to viscous damping for fluid mesh.
      - PARAM, AMLS
        Bulk Data Entry Use external AMLS eigenvalue solver.
      - PARAM, AMLSMAXR
        Bulk Data Entry Used to determine singularities in the stiffness matrix for AMLS eigenvalue solver.
      - PARAM, AMLSMEM
        Bulk Data Entry Defines the amount of memory in Gigabytes to be used by the external AMLS eigenvalue solver.
      - PARAM, AMLSNCPU
        Bulk Data Entry Used to define the number of CPUs to be used by the external AMLS eigenvalue solver.
      - PARAM, AMLSUCON
        Bulk Data Entry Constrain unconnected grids for AMLS eigenvalue solver.
      - PARAM, AMSE4CMS
        Bulk Data Entry Controls the alternate method for the creation of CMS superelements using the AMSES eigensolver.
      - PARAM, AMSE4EFM
        Bulk Data Entry Controls the activation of the enforced motion static solution in the AMSES solver in conjunction with the normal modes calculation.
      - PARAM, AMSESLM
        Bulk Data Entry Indicates if the AMSES numerical mode for enforced motion based modal dynamic analysis with large mass method will be activated or not.
      - PARAM, AMSFRMAT
        Bulk Data Entry This parameter controls the method used for modal frequency response solution when frequency-dependent materials are present and AMSES is used as the eigensolver.
      - PARAM, ASCOUP
        Bulk Data Entry Generates the fluid-structure coupling (area) matrix for use in the solution.
      - PARAM, AUNITS
        Bulk Data Entry Converts accelerations specified in units of gravity on the TRIM Bulk Data Entry to units of distance per time squared.
      - PARAM, AUTOMSET
        Bulk Data Entry Automatically convert dependent degrees-of-freedom of rigid elements to independent degrees-of-freedom.
      - PARAM, AUTOSPC
        Bulk Data Entry Automatically constrain degrees-of-freedom with no stiffness.
      - PARAM, AUTOSPRT
        Bulk Data Entry Activate inertia relief and auto-support degree-of-freedom generation.
      - PARAM, AXCYSYM
        Bulk Data Entry Allows definition of a user-specified axis of symmetry, in cyclic symmetry analysis.
      - PARAM, AXI2DTOR
        Bulk Data Entry Converts 2D axisymmetric elements in the model to general axisymmetric elements.
      - PARAM, BEAMALT
        Bulk Data Entry Used to activate an alternate formulation for CBAR and CBEAM elements.
      - PARAM, BUFFSIZE
        Bulk Data Entry Defines the maximum size in 8 byte words of the records of data written to the .op2 file.
      - PARAM, BUSHRLMT
        Bulk Data Entry Issues a WARNING when the stiffness value for rotational components on the PBUSH entry exceeds the specified limit (BUSHRLMT).
      - PARAM, BUSHSTIF
        Bulk Data Entry Specifies a value to replace large stiffness values (>1.0E+07) input in field K of the PBUSH Bulk Data Entry.
      - PARAM, BUSHTLMT
        Bulk Data Entry Issues a WARNING when the stiffness value for translational components on the PBUSH entry exceeds the specified limit (BUSHTLMT).
      - PARAM, CACONV
        Bulk Data Entry Generates files which contain the generated internal CAFLUID elements, along with the CONV entries and CHBDYE elements.
      - PARAM, CB2
        Bulk Data Entry Scale factor for direct input damping matrices.
      - PARAM, CDITER
        Bulk Data Entry Controls the activation of MPC-based Fast Contact Analysis.
      - PARAM, CDPCH
        Bulk Data Entry Controls the printing of the final state of DMIG,CDSHUT for the constrained degrees of freedom at the gap interface to the PUNCH file for MPC-based Fast Contact Analysis.
      - PARAM, CDPRT
        Bulk Data Entry Controls the printing of violations during intermediate iterations in MPC-based Fast Contact Analysis to the .out file.
      - PARAM, CHECKEL
        Bulk Data Entry Activates element quality checking.
      - PARAM, CHECKMAT
        Bulk Data Entry Activates material property checking.
      - PARAM, CHKELSET
        Bulk Data Entry Specifies or excludes an element set from element quality check.
      - PARAM, CHKGPDIR
        Bulk Data Entry Activates gap direction alignment checking.
      - PARAM, CHKM0
        Bulk Data Entry OptiStruct calculates the ratio of $\frac{m_{0}}{m_{0}^{\log}}$ and prints a WARNING if the frequency interval may not be fine enough for accurate Fatigue Damage calculation.
      - PARAM, CHKUCON
        Bulk Data Entry Controls checking for unconnected parts when the AMSES eigensolver is used.
      - PARAM, CK2
        Bulk Data Entry Scale factor for direct input stiffness matrices.
      - PARAM, CK3
        Bulk Data Entry Specifies factors for the stiffness matrix produced by GENEL cards.
      - PARAM, CM2
        Bulk Data Entry Scale factor for direct input mass matrices.
      - PARAM, CMSALOAD
        Bulk Data Entry Controls the inclusion of mass contribution from the mass matrix stored in the PUNCH DMIG or the H3D DMIG files for the generation of RFORCE and Gravity Loads.
      - PARAM, CMSDIRM
        Bulk Data Entry Allows flexible body generation when directional masses are defined in the input file.
      - PARAM, CMSGDMP
        Bulk Data Entry Global damping for CMS superelement generation runs.
      - PARAM, CMSOFST
        Bulk Data Entry Consider shell offsets for flexbody generation.
      - PARAM, CNST4FAT
        Bulk Data Entry Defines the Corner Stress type for Fatigue analysis, if Corner Stress type is not requested, via the corresponding STRESS output request.
      - PARAM, COEFFC
        Bulk Data Entry Friction coefficient on curvatures for one-step stamping simulation.
      - PARAM, COMP2SHL
        Bulk Data Entry Results of homogenization of composite properties.
      - PARAM, COMPSHST
        Bulk Data Entry Controls the transverse shear stress calculation for composite shells, (PCOMP, PCOMPP, PCOMPG) and continuum shells (PCOMPLS).
      - PARAM, CONTFEL
        Bulk Data Entry Activates contact-friendly elements in Nonlinear Static/Transient Analysis (SMDISP/LGDISP).
      - PARAM, CONVG
        Bulk Data Entry Specifies output of a separate *_CONVG.fem file containing the internally generated entries coming from CONVG.
      - PARAM, COUPMASS
        Bulk Data Entry Use coupled mass matrix approach for eigenvalue/dynamic analysis.
      - PARAM, CP2
        Bulk Data Entry Scale factor for direct input load matrices.
      - PARAM, CRTELEM
        Bulk Data Entry Controls the printing of the “n” smallest element/nodal timesteps for Nonlinear Explicit Analysis.
      - PARAM, CSTEVAL
        Bulk Data Entry Use wall time based cost evaluation for Lanczos steps.
      - PARAM, CSTOL
        Bulk Data Entry Specifies how many decimal digits may be lost to cancellation in one operation during the eigensolution process.
      - PARAM, CTSTF4PL
        Bulk Data Entry Flag for tangential stiffness of closed gaps (closed contact elements) in nonlinear preloaded linear analysis.
      - PARAM, CURVSHL2
        Bulk Data Entry Activates a correction to strain and stress calculation for second order shell elements (CQUAD8, CTRIA6) that considers strong curvature of the shell (relative to shell thickness).
      - PARAM, DDMNGRPS
        Bulk Data Entry Identifies the number of groups into which the specified MPI processes (-np) are divided.
      - PARAM, DFREQ
        Bulk Data Entry Used to determine duplicate frequencies.
      - PARAM, DISIFMCK
        Bulk Data Entry Skip indefinite mass matrix check.
      - PARAM, DISJOINT
        Bulk Data Entry Used to allow AMLS to handle disconnected parts. This can also be accomplished with PARAM, AMLSUCON.
      - PARAM, DISPFIC
        Bulk Data Entry Used to control the displacements output for the fictitious grids of CWELD, CGAP, CFAST and CSEAM elements.
      - PARAM, DSZERO
        Bulk Data Entry Sets a threshold (minimum absolute value) for the printing of Design Sensitivities.
      - PARAM, DUPTOL
        Bulk Data Entry Level of accuracy used in determining duplicate grids.
      - PARAM, EDGESTR
        Bulk Data Entry This parameter is a switch for the type of Grid Point Stress calculation for mid-edge nodes in second order elements.
      - PARAM, EFFMAS
        Bulk Data Entry Outputs modal participation factors and effective mass for normal modes analyses.
      - PARAM, EHD
        Bulk Data Entry Prints the inverse of the stiffness matrix created by static reduction to Fortran unit 3.
      - PARAM, ELASRLMT
        Bulk Data Entry Issues a WARNING when the stiffness value for rotational components on the CELAS2/CELAS4 or PELAS entry exceeds the specified limit (ELASRLMT).
      - PARAM, ELASSTIF
        Bulk Data Entry Specifies a value to replace large stiffness values (>1.0E+07) input in field K of the PELAS Bulk Data Entry.
      - PARAM, ELASTLMT
        Bulk Data Entry Issues a WARNING when the stiffness value for translational components on the CELAS2/CELAS4 or PELAS entry exceeds the specified limit (ELASTLMT).
      - PARAM, ENFMETH
        Bulk Data Entry Used to control the calculation of enforced displacement vectors in a Modal Frequency Response (MFREQ) analysis.
      - PARAM, ENFMOTN
        Bulk Data Entry Switch between relative and absolute displacement output in Modal Frequency Response Analysis with enforced motion.
      - PARAM, EPZERO
        Bulk Data Entry An upper bound for the stiffness ratio below which a degree of freedom will be regarded as an AUTOSPC candidate.
      - PARAM, ERPAREA
        Bulk Data Entry The ERP output.
      - PARAM, ERPC
        Bulk Data Entry The speed of sound used in the ERP calculation.
      - PARAM, ERPREFDB
        Bulk Data Entry Specifies the reference power value used to calculate Equivalent Radiated Power (ERP) in decibels (dB).
      - PARAM, ERPRHO
        Bulk Data Entry The fluid density used in ERP calculations.
      - PARAM, ERPRLF
        Bulk Data Entry The Radiation Loss Factor used in ERP calculation.
      - PARAM, EXCEXB
        Bulk Data Entry Controls the output of the AVL/EXCITE .exb file directly from OptiStruct.
      - PARAM, EXCOP2
        Bulk Data Entry This parameter controls the output of the AVL EXCITE _AVL.op2 file directly from OptiStruct.
      - PARAM, EXPERTNL
        Bulk Data Entry Activates a nonlinear expert system to aid in the convergence of Nonlinear (static and transient) Analysis.
      - PARAM, EXPISOP
        Bulk Data Entry This parameter controls the element integration scheme in Explicit Dynamic Analysis.
      - PARAM, EXTOUT
        Bulk Data Entry Controls the output of reduced matrices to external data files for use in subsequent analysis.
      - PARAM, FASTCONT
        Bulk Data Entry Activates the fast contact algorithm. This algorithm can only be used if the nonlinearity in the model comes from just contact (no friction allowed).
      - PARAM, FASTFR
        Bulk Data Entry Controls the activation of a faster, alternative method (FASTFR) for Modal Frequency Response Analysis.
      - PARAM, FASTINIT
        Bulk Data Entry Controls the initialization of contact status in Fast Contact Analysis.
      - PARAM, FCACSV
        Bulk Data Entry This parameter controls the output of data in an Acoustic Complex Eigenvalue Analysis. If activated, the output is available in a <filename>.cmode.csv file.
      - PARAM, FFRS
        Bulk Data Entry Used to activate the external FastFRS (Fast Frequency Response Solver).
      - PARAM, FFRSLFREQ
        Bulk Data Entry Defines a frequency cut-off value in Hertz used to partition the structural system into low frequency and high frequency parts.
      - PARAM, FFRSMEM
        Bulk Data Entry Defines the amount of memory in Gigabytes to be used by the external FastFRS modal equation solver.
      - PARAM, FFRSNCPU
        Bulk Data Entry Defines the number of CPUs to be used by the external FastFRS solver.
      - PARAM, FIXRBE3
        Bulk Data Entry Used to automatically fix invalid RBE3’s.
      - PARAM, FLEXH3D
        Bulk Data Entry Generates flexh3d files for flexible bodies in an MBD analysis.
      - PARAM, FLIPOK
        Bulk Data Entry Allows tetrahedral elements to invert during shape optimization.
      - PARAM, FLLWER
        Bulk Data Entry Calculation of follower forces introduced by pressure loads and concentrated forces in large displacement nonlinear analysis.
      - PARAM, FRIC
        Bulk Data Entry Defines multiplier for K2PP reference.
      - PARAM, FZERO
        Bulk Data Entry Identifies the maximum frequency of a rigid body mode for the Lanczos eigensolver.
      - PARAM, G
        Bulk Data Entry Specifies the uniform structural damping coefficient for dynamic analyses.
      - PARAM, GE4FRSTF
        Bulk Data Entry Controls the contribution of material damping, in addition to the stiffness contribution in the element force calculation for frequency response analysis.
      - PARAM, GE4TRSTF
        Bulk Data Entry Controls the contribution from damping, in addition to the stiffness contribution in the element force calculation for Linear Transient Analysis.
      - PARAM, GE_MOD
        Bulk Data Entry Modifies specified GE values.
      - PARAM, GFL
        Bulk Data Entry Specifies the uniform fluid damping coefficient for dynamic analyses.
      - PARAM, GLOBEXPT
        Bulk Data Entry Applies to Global-Local Modeling. Expanding the interpolation patch results in a smoother solution near the cut surface.
      - PARAM, GMAR
        Bulk Data Entry Controls the accuracy of the external AMLS eigenvalue solution.
      - PARAM, GMAR1
        Bulk Data Entry Controls the accuracy of the external AMLS eigenvalue solution.
      - PARAM, GPSLOC
        Bulk Data Entry Controls where the grid point stresses are calculated for output to the .mnf file.
      - PARAM, GRDPNT
        Bulk Data Entry Obsolete Nastran parameter that will give information about the mass properties of the structure.
      - PARAM, GRDPNTCM
        Bulk Data Entry The CMASS1 and CMASS2 elements are included or excluded in the Grid Point Weight Generation output.
      - PARAM, GRIDFORM
        Bulk Data Entry Controls the output format of the .grid file.
      - PARAM, GYRO1D
        Bulk Data Entry Activates/deactivates the calculation of 1D Gyroscopic Matrix for 1D Rotors in Rotor dynamics.
      - PARAM, GYROAVG
        Bulk Data Entry Used to select the frequency response analysis formulation type for rotor dynamics analysis.
      - PARAM, GYROTIMO
        Bulk Data Entry Controls the inclusion or exclusion of shear effect in the beam gyroscopic matrix.
      - PARAM, HASHASSM
        Bulk Data Entry Enables hash-table based assembly.
      - PARAM, HEX8ALT
        Bulk Data Entry Controls an alternative formulation of 8-noded CHEXA element for linear analysis.
      - PARAM, HFREQ
        Bulk Data Entry Specifies the upper bound of the frequency range of interest for modal combination.
      - PARAM, HFREQFL
        Bulk Data Entry Excludes modes with frequencies greater than HFREQFL in Coupled Modal Frequency Response Analysis (Acoustic Analysis).
      - PARAM, HGHCMPOK
        Bulk Data Entry Used to turn on or off the check for negative and very large compliance values.
      - PARAM, HOURGLS
        Bulk Data Entry Controls the hourglass type.
      - PARAM, IMPLOUT
        Bulk Data Entry On-the-fly incremental results of nonlinear implicit (static and transient) analysis.
      - PARAM, INREL
        Bulk Data Entry Controls the calculation of inertia relief.
      - PARAM, INRELBCK
        Bulk Data Entry This parameter controls the handling of buckling analysis based under inertia relief analysis.
      - PARAM, INRELOUT
        Bulk Data Entry Controls the output of inertia relief-corrected applied loading in conjunction with OLOAD request.
      - PARAM, INTRFACE
        Bulk Data Entry Generates the .interface file to verify if proper connection has been established between the Fluid and Structure meshes at the interface.
      - PARAM, IR4NLCON
        Bulk Data Entry Inertia relief for nonlinear analysis.
      - PARAM, ISTRSBAL
        Bulk Data Entry Controls the application of initial stress over the nonlinear subcase.
      - PARAM, ITAPE
        Bulk Data Entry Writes the 'Tape Label' at the beginning of the OUTPUT2 results file.
      - PARAM, K4CUTOFF
        Bulk Data Entry Sets cut-off value if the low rank representation for the structural damping matrix is selected.
      - PARAM, K4METH
        Bulk Data Entry Specifies the value of PARAM,LOWRANK, which indicates the solution type for the faster Modal Frequency Response solution method invoked by PARAM,FASTFR and the FastFRS interface invoked by PARAM,FFRS.
      - PARAM, KDAMP
        Bulk Data Entry Enters viscous modal damping into the stiffness matrix as structural damping.
      - PARAM, KGRGD
        Bulk Data Entry Include contributions from rigid elements in the geometric stiffness matrix.
      - PARAM, KISSSOFT
        Bulk Data Entry Controls the creation of the condensed stiffness matrix in an ASCII file to be used by the KISSsoft program.
      - PARAM, KSMNL4PL
        Bulk Data Entry Control stiffness calculations in linear analysis that is preloaded with small displacement NLSTAT analysis.
      - PARAM, KTPLAST
        Bulk Data Entry Beneficial for problems involving a combination of plasticity, contact, and pretension.
      - PARAM, LCLGRDST
        Bulk Data Entry This parameter can be defined in the local model of a submodeling job, to output the mapping information of each local node to the global nodes, for all the local nodes in a set.
      - PARAM, LFREQ
        Bulk Data Entry Used to remove the Rigid Body Modes from the Modal Space.
      - PARAM, LFREQFL
        Bulk Data Entry Excludes modes with frequencies lower than LFREQFL in Coupled Modal Frequency Response Analysis (Acoustic Analysis).
      - PARAM, LFREQH3D
        Bulk Data Entry This parameter can be used to request only the modes (structural or coupled) that satisfy the lower bound of frequency, for H3D output.
      - PARAM, LGDISP
        Bulk Data Entry Activates Large Displacement Nonlinear Analysis.
      - PARAM, LMSOUT
        Bulk Data Entry Outputs the condensed Flex Body Modes, full Diagonal Mass Matrix, and modal stresses to the .op2 file.
      - PARAM, LOWRANK
        Bulk Data Entry This parameter is obsolete. Use PARAM,K4METH to control the value of LOWRANK.
      - PARAM, LSNLEXP
        Bulk Data Entry In the small displacement NLSTAT solution that has difficulties converging, the “expert system” will try, among other remedies, activation of Line Search.
      - PARAM, MASSDMIG
        Bulk Data Entry For static condensation with ASET of a static loadcase, the reduced stiffness matrix [k] and load vector {p} are created.
      - PARAM, MATFREQ
        Bulk Data Entry Turns off any frequency-dependent materials (MATF#) that are present in the model.
      - PARAM, MAXDAMP
        Bulk Data Entry Identifies the maximum number of residual vectors to be calculated.
      - PARAM, MAXRATIO
        Bulk Data Entry Defines the maximum allowed value of the ratio of terms on the diagonal of the stiffness matrix to the corresponding diagonal terms of the triangular factor matrix during decomposition.
      - PARAM, MBDDAMP
        Bulk Data Entry Specifies inclusion of the generalized damping matrix in the Flex H3D file.
      - PARAM, MBDH3D
        Bulk Data Entry Choose the type of the results output to the .h3d file for MBD analyses.
      - PARAM, MBDREC
        Bulk Data Entry Creates small and large flexible body files during Component Mode Synthesis (CMS).
      - PARAM, MCHGRMV
        Bulk Data Entry Controls the participation of elements removed by MODCHG in the analysis.
      - PARAM, MDK4OPT
        Bulk Data Entry Controls the internal calculation of material damping when different material damping values (GE on MATx) are specified for different regions in a model.
      - PARAM, MEMTRIM
        Bulk Data Entry Activates/deactivates the memory-trim feature when using AMLS eigensolver.
      - PARAM, MFILTER
        Bulk Data Entry Defines a threshold for the mode tracking matrix to check eigenvector correspondence.
      - PARAM, MODETRAK
        Bulk Data Entry Tracks mode numbers by comparing eigenvectors between iterations.
      - PARAM, MVASPCON
        Bulk Data Entry Controls the auto SPC of degrees of freedom with both mass and viscous damping.
      - PARAM, MZEROHZ
        Bulk Data Entry Controls frequency inclusion in moments calculation for random response fatigue analysis.
      - PARAM, NBZRCSR
        Bulk Data Entry Identifies whether the Number of Peaks or Number of Zero Crossings are used for NARROW band model in Random Response Fatigue Analysis.
      - PARAM, NEGMASS
        Bulk Data Entry Allows run to proceed with negative diagonal mass terms.
      - PARAM, NEWCRD
        Bulk Data Entry Used to control switching between alternative and traditional constraint reduction methods.
      - PARAM, NLFAT
        Bulk Data Entry Forces OptiStruct to run models in which fatigue solutions reference small displacement nonlinear analysis (NLSTAT) subcases.
      - PARAM, NLINISOL
        Bulk Data Entry The optimization process involving nonlinear analysis, in the subsequent optimization iteration the solution of the nonlinear problem.
      - PARAM, NLMON
        Bulk Data Entry This parameter activates Nonlinear Results Monitoring. Currently, only displacement results monitoring is available.
      - PARAM, NOUTCYC
        Bulk Data Entry Frequency for output control. OptiStruct will write results to the .out file in every NOUTCYC step.
      - PARAM, NPRBAR
        Bulk Data Entry Controls the number of the output INFORMATION #741 for RBAR element.
      - PARAM, NPRBE2
        Bulk Data Entry Controls the number of the output INFORMATION #741 for RBE2 element.
      - PARAM, NPRGDE
        Bulk Data Entry Controls the number of the output INFORMATION #742.
      - PARAM, NUMEG
        Bulk Data Entry Specifies the anticipated number of modes to be calculated in order to estimate disk space usage.
      - PARAM, ODS
        Bulk Data Entry An Operating Deformed Shape (ODS) run requires the output for all the elements or all the grids for limited loading frequencies of interest.
      - PARAM, OGEOM
        Bulk Data Entry Outputs model data to the OUTPUT2 results file.
      - PARAM, OMACHPR
        Bulk Data Entry Selects newer version of certain OUTPUT2 datablocks.
      - PARAM, OMID
        Bulk Data Entry Outputs stress and strain results for shell and membrane elements with reference to the material coordinate system.
      - PARAM, OP2GM34
        Bulk Data Entry Controls the output of GEOM3 and GEOM4 data blocks to the .op2 file.
      - PARAM, OPTI
        Bulk Data Entry This parameter can be used to activate the new OPTI format, which is enhanced with labels for improved readability.
      - PARAM, ORIGK4
        Bulk Data Entry The value of PARAM,ORIGK4 is used to replace the GE damping field on any material Bulk Data Entry referenced by superelements.
      - PARAM, PBTFCAP
        Bulk Data Entry This parameter limits the applicability of PARAM,PBUSHTF properties.
      - PARAM, PBUSHT
        Bulk Data Entry Used to turn ON/OFF the usage of all PBUSHT Bulk Data Entries in the model.
      - PARAM, PBUSHTF
        Bulk Data Entry Specifies the reference frequency value for scaling factor lookup to update the nominal PBUSH Stiffness (K) values.
      - PARAM, PEACTDMG
        Bulk Data Entry Controls the output of the .eactdmg file for Pseudo Damage method in fatigue analysis.
      - PARAM, PELAST
        Bulk Data Entry Used to turn ON/OFF the usage of all PELAST Bulk Data Entries in the model.
      - PARAM, PENT2ALT
        Bulk Data Entry Controls an alternative formulation of 15-noded CPENTA element for linear analysis.
      - PARAM, PLIGEXT
        Bulk Data Entry Prints the applied load vector in DMIG form to the .pligext file.
      - PARAM, PNLSIZ
        Bulk Data Entry Increases the starting size of panel to the specified value.
      - PARAM, POST
        Bulk Data Entry Generates an OUTPUT2 results file.
      - PARAM, POSTEXT
        Bulk Data Entry Outputs the modal complex stiffness matrix and modal viscous damping matrix to the OUTPUT2 results file.
      - PARAM, PREFDB
        Bulk Data Entry Used to activate dB and dB(A) output in H3D and PUNCH file formats for Fluid-Structure Coupled Frequency Response Analysis.
      - PARAM, PRESUBNL
        Bulk Data Entry Forces OptiStruct to run models in which Linear Buckling Analysis or Preloaded Analysis is defined, in conjunction with nonlinear materials (MATS1, MATHE, or MGASK) or Large Displacement Nonlinear Analysis.
      - PARAM, PRGPST
        Bulk Data Entry Outputs AUTOSPC information to the .out file.
      - PARAM, PRINFACC
        Bulk Data Entry Controls the output of inertial relief rigid body forces and accelerations.
      - PARAM, PRTDES
        Bulk Data Entry Controls the printing of Design Variables and Design Entities to the .out file.
      - PARAM, PRTNORM
        Bulk Data Entry Defines the maximum number of contributions printed for each norm response under the norm response itself in the .out file for an Optimization run.
      - PARAM, PRTRET
        Bulk Data Entry Controls the printing of Retained Response information to the .out file.
      - PARAM, PRTMGG
        Bulk Data Entry Defines the Mass Matrix.
      - PARAM, PSDPRINC
        Bulk Data Entry This parameter controls the output of PSD/RMS Absolute Maximum Principal Stress and PSD/RMS Absolute Maximum Principal Strain for Random Response Analysis.
      - PARAM, RBD2ELEM
        Bulk Data Entry Used to control how RBODY entries in the model are internally processed.
      - PARAM, RBE2FREE
        Bulk Data Entry Used to convert ERROR 725 into WARNING 825 when singular RBE2 elements are present in the model.
      - PARAM, RBE3COL
        Bulk Data Entry This parameter controls the handling of RBE3 elements.
      - PARAM, RBE3FREE
        Bulk Data Entry Used to convert ERROR 772 into WARNING 824 when free spiders on RBE3 elements are present in the model. These free spiders may contain singular degrees-of-freedom.
      - PARAM, RBMEIG
        Bulk Data Entry Defines the cut-off eigenvalue for determining rigid body modes calculated by AMLS.
      - PARAM, REANAL
        Bulk Data Entry Reanalyze the final iteration of a topology optimization without penalization.
      - PARAM, RECOVER
        Bulk Data Entry Allows you to request full-structure global mode shape output instead of the modes of the condensed system generated during Component Mode Synthesis (CMS).
      - PARAM, REFPNT
        Bulk Data Entry The reference point for Inertia Relief of the model.
      - PARAM, RENUMOK
        Bulk Data Entry Allows you to correctly renumber the reversed (but acceptable) sequence of element grids without having to run (import and re-export) the model through HyperMesh.
      - PARAM, RFIOUT
        Bulk Data Entry Controls the output of modal super element for use in the RecurDyn multibody dynamics software from FunctionBay.
      - PARAM, RHOCP
        Bulk Data Entry The scale factor used to calculate ERP in decibels (dB).
      - PARAM, RICARDO
        Bulk Data Entry Controls the creation of the condensed flex body modes and full diagonal mass matrix to the .op2 file to be used by VALDYN from Ricardo Software.
      - PARAM, ROMAX
        Bulk Data Entry Controls the creation of the condensed stiffness, mass, and displacement recovery matrices for use with Romax Technology.
      - PARAM, RSPLICOR
        Bulk Data Entry RSPLINE end rotation correction.
      - PARAM, S2K
        Bulk Data Entry Controls the creation of analysis results to be used by the STRENGTH2000 program to the .op2 file.
      - PARAM, SBTOLRTR
        Bulk Data Entry Used to modify the tolerance value for symmetric beams when they are used for rotor modeling.
      - PARAM, SEP1XOVR
        Bulk Data Entry The old and new location of moved shell grid points are printed if SEP1XOVR = 16.
      - PARAM, SEPLOT
        Bulk Data Entry Outputs display model to .seplot file, from a CMS run.
      - PARAM, SHEARALT
        Bulk Data Entry Activates an alternative formulation for CSHEAR elements.
      - PARAM, SHELLLG
        Bulk Data Entry Activate an alternative 1^st order Nonlinear Large Displacement shell element (CQUAD4 and CTRIA3 elements).
      - PARAM, SHELLTI
        Bulk Data Entry Identifies the handling of nodal shell thicknesses defined on the shell element entries.
      - PARAM, SHELOS11
        Bulk Data Entry Allows you to revert to the first order shell element formulation (for CQUAD4 and CTRIA3) used in version 11.0.240 and earlier.
      - PARAM, SHL2MEM
        Bulk Data Entry A shell property (defined by the PSHELL Bulk Data Entry) is automatically converted into a membrane property if the membrane thickness (field T) of the PSHELL Bulk Data Entry is less than the value specified using PARAM, SHL2MEM.
      - PARAM, SHPBCKOR
        Bulk Data Entry Defines the type and order of approximation used in plate bending geometric stiffness for linear shell elements (CQUAD4, CTRIA3).
      - PARAM, SIGMA
        Bulk Data Entry The Stefan-Boltzmann constant used in Radiation Heat Transfer calculations.
      - PARAM, SIMPACK
        Bulk Data Entry Requests generation of the SIMPACK .fbi file containing flexible body information for SIMPACK analysis.
      - PARAM, SIMVER
        Bulk Data Entry This parameter can be used to select the SIMPACK version for multibody dynamics analysis.
      - PARAM, SORTCON
        Bulk Data Entry Controls the output of violated constraints to the .out file from an optimization.
      - PARAM, SPLC
        Bulk Data Entry Specifies the speed of sound used in the wave number and the complex particle velocity vector calculations.
      - PARAM, SPLFAC
        Bulk Data Entry Specifies the scale factor (q) used to calculate the Sound Pressure Level in Radiated Sound Analysis.
      - PARAM, SPLREFDB
        Bulk Data Entry Specifies the reference sound pressure value used to calculate the Sound Pressure Level (SPL) in decibels (dB).
      - PARAM, SPLRHO
        Bulk Data Entry Specifies the density of the acoustic medium in the calculation of the complex acoustic sound pressure and the complex particle velocity vector.
      - PARAM, SRCOMPS
        Bulk Data Entry Outputs the strength ratios for composite elements that have failure indices requested.
      - PARAM, SS2GCR
        Bulk Data Entry Controls the accuracy of the external AMLS eigenvalue solution.
      - PARAM, STRTHR
        Bulk Data Entry Used to specify the von Mises stress threshold above which the stress results are output for a model.
      - PARAM, SUBRESVC
        Bulk Data Entry Used to control whether residual vector generation is subcase-dependent when the AMSES eigensolver is used.
      - PARAM, TABS
        Bulk Data Entry Converts units of the temperature input (Fahrenheit or Celsius) to the absolute temperature (Degrees Kelvin).
      - PARAM, TCLTINIT
        Bulk Data Entry Defines the lower threshold value used for the HyperMesh command files *.HM.comp.tcl and *.HM.ent.tcl.
      - PARAM, TCLTSTEP
        Bulk Data Entry Defines the step or interval value used for the HyperMesh command files *.HM.comp.tcl and *.HM.ent.tcl.
      - PARAM, THCNTPEN
        Bulk Data Entry Controls the penalty factor used in thermal contact analysis.
      - PARAM, THMLSTN
        Bulk Data Entry Select the thermal strain formula.
      - PARAM, TOLRSC
        Bulk Data Entry Connecting grid points of the shell element are moved onto the solid face.
      - PARAM, TRAKMETH
        Bulk Data Entry Used to select the criterion employed for mode tracking.
      - PARAM, TRAKMTX
        Bulk Data Entry Controls output of the mode tracking matrix during optimization.
      - PARAM, TPS
        Bulk Data Entry Activates fast transient response analysis (only shell stress results output).
      - PARAM, UCORD
        Bulk Data Entry Specifies the coordinate system in which the mass moment of inertia is output. It also can be used to control the point about which the mass moment of inertia is calculated.
      - PARAM, UFREQH3D
        Bulk Data Entry This parameter can be used to request only the modes (structural or coupled) that satisfy the upper bound of frequency, for H3D output.
      - PARAM, UFREQPCH
        Bulk Data Entry This parameter can be used to request only the modes (structural or coupled) that satisfy the upper bound of frequency, for PCH output.
      - PARAM, UHT
        Bulk Data Entry Outputs the UHT data block.
      - PARAM, UNSM2SM
        Bulk Data Entry This parameter is used to convert an unsymmetrical K2PP or M2PP matrix to a symmetrical matrix.
      - PARAM, UNSYMSLV
        Bulk Data Entry Controls the inclusion or exclusion of non-symmetric terms in the tangent stiffness matrix due to friction in frictional contact problems.
      - PARAM, VAPMTV
        Bulk Data Entry This parameter is used to define the vacuum permittivity for piezoelectric materials.
      - PARAM, VMMASS
        Bulk Data Entry Used with MFLUID and PARAM,GRDPNT.
      - PARAM, VMOPT
        Bulk Data Entry Allows you to prevent the inclusion of the Virtual Mass Matrix in the Regular Mass Matrix for Modal Dynamic Subcases. In such cases, the virtual mass is added after the eigen solution and modes are modified based on the virtual mass matrix.
      - PARAM, VREF
        Bulk Data Entry Used in aeroelastic flutter analysis to specify a factor to divide the velocities.
      - PARAM, W3
        Bulk Data Entry Converts structural damping to equivalent viscous damping for transient analysis.
      - PARAM, W4
        Bulk Data Entry Converts structural damping to equivalent viscous damping for transient analysis.
      - PARAM, WRH
        Bulk Data Entry Used to include or exclude rotor material hybrid damping in rotor dynamics analysis.
      - PARAM, WR3
        Bulk Data Entry Used to include or exclude rotor structural damping in rotor dynamics analysis.
      - PARAM, WR4
        Bulk Data Entry Used to include or exclude rotor material damping in rotor dynamics analysis.
      - PARAM, WTMASS
        Bulk Data Entry Converts weights to masses using this multiplier.
      - PARAM, XB
        Bulk Data Entry This parameter can be used to print nodal coordinate information in the local coordinate system in an additional field/column in the .h5 file.
      - PARAM, XPOST
        Bulk Data Entry Used to create the .elfo (element forces), .elsh (element shear), and .endl (end loads) output files.
      - PARAM, ZAERO
        Bulk Data Entry Outputs an ASCII file (.zaero) containing the normal modes data for the requested grids. This file can be used to import into ZAERO software, for further aeroelastic analysis.
    - PAXI
      Bulk Data Entry Defines the properties of 2D axisymmetric elements. Referenced by CTAXI and CQAXI entries.
    - PAXIG
      Bulk Data Entry Defines the properties of general axisymmetric elements. References by the CTAXIG and CQAXIG elements.
    - PBAR
      Bulk Data Entry Defines the properties of a simple beam (bar), which is used to create bar elements via the CBAR entry.
    - PBARL
      Bulk Data Entry Defines the properties of a simple beam (bar) by cross-sectional dimensions, which is used to create bar elements via the CBAR entry.
    - PBEAM
      Bulk Data Entry Defines the properties of beam elements defined via the CBEAM entry.
    - PBEAML
      Bulk Data Entry Defines the properties of a beam element by cross-sectional dimensions that are used to create beam elements via the CBEAM entry.
    - PBUSH
      Bulk Data Entry Defines the nominal property values for a generalized spring-damper-mass structural element.
    - PBUSH1D
      Bulk Data Entry Defines the linear and nonlinear properties for a one-dimensional spring-and-damper structural element.
    - PBUSHFX
      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.
    - PBUSHT
      Bulk Data Entry Defines property values for a generalized spring and damper structural element.
    - PCOHE
      Bulk Data Entry Defines the properties for cohesive elements.
    - PCOMP
      Bulk Data Entry Defines the structure and properties of an n-ply composite laminate material.
    - PCOMPG
      Bulk Data Entry Defines the structure and properties of a composite laminate material, allowing for global ply identification.
    - PCOMPLS
      Bulk Data Entry Defines global ply-based composite properties for continuum shell composites.
    - PCOMPP
      Bulk Data Entry Defines the properties of a composite laminate material used in ply-based composite definition.
    - PCONT
      Bulk Data Entry Defines properties of a CONTACT interface.
    - PCONTEC
      Bulk Data Entry Defines Contact Electric Conductance Coefficient (CECC) for CONTACT elements in electrical analysis.
    - PCONTHT
      Bulk Data Entry Defines conductance for CONTACT elements in heat transfer analysis.
    - PCONV
      Bulk Data Entry Defines a free convection boundary condition properties.
    - PCONVLIB
      Bulk Data Entry Defines the external function to be called to calculate time and temperature-dependent free-convection coefficient in a convection element.
    - PDAMP
      Bulk Data Entry Specifies the damping of a scalar damper element using defined CDAMP1 or CDAMP3 entry.
    - PEAKOUT
      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.
    - PELAS
      Bulk Data Entry Used to define the stiffness and stress coefficient of a scalar elastic element (spring) by means of the CELAS1 or CELAS3 entry.
    - PELASFX
      Bulk Data Entry Used to define the stiffness and stress coefficient of a scalar elastic element (spring) by means of the CELAS1 or CELAS3 entry.
    - PELAST
      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.
    - PERBC
      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.
    - PFAST
      Bulk Data Entry Define properties of connector (CFAST) elements.
    - PFASTG
      Bulk Data Entry Defines properties for Fastener Element Connection specified by a CFASTG entry.
    - PFAT
      Bulk Data Entry Defines element properties for fatigue analysis.
    - PFATSDR
      Bulk Data Entry Defines properties for solder fatigue analysis.
    - PFATSMW
      Bulk Data Entry Defines properties for Seam Weld Fatigue Analysis.
    - PFATSPW
      Bulk Data Entry Defines properties for Spot Weld Fatigue Analysis.
    - PFPATH
      Bulk Data Entry Defines a one-step transfer path analysis.
    - PFBODY
      Bulk Data Entry Defines a flexible body out of a list of finite element properties, elements, and grid points.
    - PGAP
      Bulk Data Entry Defines properties of the gap (CGAP or CGAPG) elements.
    - PGAPEC
      Bulk Data Entry Defines electrical resistance properties for the gap elements (CGAP or CGAPG) in electrical analysis.
    - PGAPHT
      Bulk Data Entry Defines heat transfer conduction properties of the gap (CGAP or CGAPG) elements for heat transfer analysis.
    - PGASK
      Bulk Data Entry Defining the properties for solid gasket elements.
    - PHFSHL
      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.
    - PJOINTG
      Bulk Data Entry Defines the properties for a joint connection between two grids via the JOINTG Bulk Data Entry.
    - PLOAD
      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.
    - PLOAD1
      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.
    - PLOAD2
      Bulk Data Entry Defines a uniform static pressure load applied to two-dimensional elements, or a SET of such elements.
    - PLOAD4
      Bulk Data Entry Defines a load on a face of a HEXA, PENTA, TETRA, PYRA, TRIA3, TRIA6, QUAD4, or QUAD8 element.
    - PLOADE1
      Bulk Data Entry Defines an in-plane surface traction on the edge of CTPSTN, CQPSTN, CTPSTS, and CQPSTS elements.
    - PLOADSF
      Bulk Data Entry Parameters of pressure loads on a surface defined by a SURF Bulk Data Entry or SET Bulk Data Entry.
    - PLOADX1
      Bulk Data Entry Defines a static surface traction on the CQAXI, CTAXI, CTRIAX6, CQAXIG and CTAXIG axisymmetric elements. The PLOADX1 entry can be defined as follower loads in Large Displacement Nonlinear Analysis.
    - PLOADXG
      Bulk Data Entry Defines a surface traction on the general axisymmetric elements CQAXIG and CTAXIG.
    - PLOTEL
      Bulk Data Entry Defines a one-dimensional dummy element for use in plotting.
    - PLOTEL3
      Bulk Data Entry Defines a three-noded, two-dimensional dummy element for use in plotting.
    - PLOTEL4
      Bulk Data Entry Defines a four-noded, two-dimensional dummy element for use in plotting.
    - PLSOLID
      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.
    - PLY
      Bulk Data Entry Defines the properties of a ply used in ply-based composite definition.
    - PMASS
      Bulk Data Entry Defines the mass value of a scalar mass element (CMASS1 or CMASS3 entry).
    - PPLANE
      Bulk Data Entry Defines the properties of plane strain elements (CTPSTN, CQPSTN, CTPSTS, and CQPSTS).
    - PRBODY
      Bulk Data Entry Defines a rigid body out of a list of finite element properties, elements and grid points.
    - PRETENS
      Bulk Data Entry Defines 1D or 3D pre-tensioned bolt section.
    - PRETPRM
      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.
    - PROD
      Bulk Data Entry Defines the properties of a rod, which is referenced by the CROD entry.
    - PRSPENE
      Bulk Data Entry Defines a pressure penetration load which can simulate fluid penetrating through the surfaces on a contact interface.
    - PSEAM
      Bulk Data Entry Define properties of connector (CSEAM) elements.
    - PSEC
      Bulk Data Entry Defines property information for planar section elements used in the definition of arbitrary beam cross-sections.
    - PSHEAR
      Bulk Data Entry Defines the properties of a shear panel.
    - PSHELL
      Bulk Data Entry Defines the membrane, bending, transverse shear, and membrane-bending coupling of shell elements.
    - PSOLID
      Bulk Data Entry Defines the properties of solid elements, referenced by CHEXA, CPENTA, CPYRA and CTETRA Bulk Data Entries.
    - PSURF
      Bulk Data Entry Defines properties of a contact surface.
    - PTADD
      Bulk Data Entry Defines a pretension load as a linear combination of load sets defined via PTFORCE, PTFORC1, PTADJST and PTADJS1 entries.
    - PTADJS1
      Bulk Data Entry Defines adjustment (additional shortening) on a set of pretension sections.
    - PTADJST
      Bulk Data Entry Defines the adjustment (shortening) on a pretension section.
    - PTFORCE
      Bulk Data Entry Defines pretensioning force on pretension section.
    - PTFORC1
      Bulk Data Entry Defines pretensioning force on a set of pretension sections.
    - PTUBE
      Bulk Data Entry Defines the properties of a thin-walled cylindrical tube element, referenced by a CTUBE entry.
    - PVISC
      Bulk Data Entry Defines properties of a one-dimensional viscous damping element (CVISC entry).
    - PWELD
      Bulk Data Entry Defines properties of connector (CWELD) elements.
    - QBDY1
      Bulk Data Entry Defines a uniform heat flux for CHBDYE elements.
    - QBDYLIB
      Bulk Data Entry Defines the external function to be called to calculate time and temperature-dependent Uniform Heat Flux values.
    - QVOL
      Bulk Data Entry Defines a rate of volumetric heat addition in a conduction element.
    - QVOLLIB
      Bulk Data Entry Defines the external function called to calculate time and temperature-dependent rate of volumetric heat addition in a conduction element.
    - RADBC
      Bulk Data Entry Defines the radiation boundary conditions and identifies CHBDYE entries for heat transfer analysis via radiation.
    - RADM
      Bulk Data Entry Defines the radiation material properties of a surface element for heat transfer analysis.
    - RADSND
      Bulk Data Entry Defines a set of grid points where the sound will be calculated as well as the panels that are generating the sound.
    - RANDPS
      Bulk Data Entry Defines load set power spectral density factors for use in random analysis having the frequency dependent form $S_{j k} (Ω) = (X + i Y) G (Ω)$ .
    - RANDT1
      Bulk Data Entry Defines time lag constants for use in random analysis autocorrelation function computation.
    - RBADD
      Bulk Data Entry Defines a rigid body as a combination of Rigid Bodies (RBODY).
    - RBAR
      Bulk Data Entry Defines a rigid bar with six degrees-of-freedom at each end.
    - RBE1
      Bulk Data Entry Defines a rigid body connected to an arbitrary number of grid points.
    - RBE2
      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.
    - RBE2GS
      Bulk Data Entry Defines a rigid element connecting two grid points which are closest to the grid point referenced by the field GS.
    - RBE3
      Bulk Data Entry Defines the motion at a "reference" grid point as the weighted average of the motions at a set of other grid points.
    - RBODY
      Bulk Data Entry Defines a rigid body as a set of elements, grid points.
    - RCROSS
      Bulk Data Entry Defines a pair of response quantities for computing the cross-power spectral density functions in random response analysis.
    - RELOC
      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).
    - RFORCE
      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.
    - RGYRO
      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.
    - RJOINT
      Bulk Data Entry Defines a Rigid Joint connection at two coincident grids.
    - RLOAD1
      Bulk Data Entry Defines a frequency-dependent dynamic load of the form: $P (f) = A (C (f) + i D (f)) e^{i (θ - 2 π f τ)}$ for use in frequency response problems.
    - RLOAD2
      Bulk Data Entry Defines a frequency-dependent dynamic load of the form $P (f) = A * B (f) e^{i (φ (f) + θ - 2 π f τ)}$ for use in frequency response problems.
    - ROTOR
      Bulk Data Entry 3D Rotor Definition. Specifies list of sets, elements or properties that comprise the rotor 3D model.
    - ROTORG
      Bulk Data Entry 1D rotor definition. Specifies grids that determine the Rotor Line model.
    - RROD
      Bulk Data Entry Defines a pin-ended rod that is rigid in extension.
    - RSPEC
      Bulk Data Entry Specifies directional combination method, modal combination method, excitation direction(s), response spectra and scale factors for Response Spectrum Analysis.
    - RSPEED
      Bulk Data Entry Specifies a set of reference rotor speed values for asynchronous analysis in Rotor Dynamics.
    - RSPINR
      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.
    - RSPINT
      Bulk Data Entry Defines the rotor spin rates and rotor damping parameters with respect to time during a Transient Rotor Dynamics Analysis.
    - RSPLINE
      Bulk Data Entry Defines multi-point constraints for the interpolation of displacements at grid points.
    - RSSCON
      Bulk Data Entry Defines multi-point constraints to model clamped connections of shell-to-solid elements.
    - RSSCON1
      Bulk Data Entry Defines a set of constraints for shell-to-solid connection on surfaces.
    - RVDOF
      Bulk Data Entry Defines the degrees of freedom where the residual vectors are to be calculated.
    - RVDOF1
      Bulk Data Entry Defines the degrees of freedom where the residual vectors are to be calculated.
    - SEBULK
      Bulk Data Entry Defines superelement boundary search options and the type of superelement.
    - SECONCT
      Bulk Data Entry Defines grid and scalar point connection procedures for a partitioned superelement.
    - SECSET
      Bulk Data Entry Defines free boundary degrees-of-freedom for One-Step Superelement Analysis.
    - SECSET1
      Bulk Data Entry Defines free boundary degrees-of-freedom to be free for use in One-Step Superelement Analysis (Alternate Format).
    - SECTION
      Bulk Data Entry Defines a user-defined cross-section based on a specific face of the model.
    - SELOC
      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.
    - SENSOR
      Bulk Data Entry Sensors may be used to activate loads.
    - SENSRAD
      Bulk Data Entry Defines a union of several SENSOR entries.
    - SEQSET
      Bulk Data Entry Defines the generalized degrees-of-freedom of the superelement for use in One-Step Superelement Analysis.
    - SEQSET1
      Bulk Data Entry Defines the generalized degrees-of-freedom of the superelement for use in One-Step Superelement Analysis (Alternate Format).
    - SESET
      Bulk Data Entry Defines the interior grid points for One-Step Superelement Analysis.
    - SET
      Bulk Data Entry Defines a set of grids, elements, design variables, MBD entities, mode numbers, frequencies or times for reference by other input definitions.
    - SET1
      Bulk Data Entry Defines a list of structural grid points or element identification numbers.
    - SET3
      Bulk Data Entry Defines a set of grids or elements.
    - SETREE
      Bulk Data Entry Defines the Superelement Tree for One-Step Superelement Analysis.
    - SLOAD
      Bulk Data Entry Defines concentrated static loads on scalar, grid or fluid points.
    - SOLVTYP
      Bulk Data Entry Defines the solver type to be used for static and dynamic analysis.
    - SPC
      Bulk Data Entry This entry can be used to define single-point constraints and enforced displacements for structural Analysis.
    - SPC1
      Bulk Data Entry Defines sets of single-point constraints and thermal boundary conditions.
    - SPCADD
      Bulk Data Entry Defines a single-point constraint set as a union of single-point constraint sets defined via SPC or SPC1 entries.
    - SPCD
      Bulk Data Entry This entry can be used to define enforced displacement value for Static Analysis.
    - SPCDLIB
      Bulk Data Entry Defines the external function to be called to calculate time and temperature-dependent SPCD temperature values.
    - SPCOFF
      Bulk Data Entry Defines degrees-of-freedom to be excluded from AUTOSPC.
    - SPCOFF1
      Bulk Data Entry Defines degrees-of-freedom to be excluded from AUTOSPC.
    - SPCP
      Bulk Data Entry Defines the flow pressure boundary conditions for Darcy Flow Analysis.
    - SPLINE1
      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.
    - SPLINE2
      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.
    - SPLINE4
      Bulk Data Entry Defines a curved surface spline for interpolating motion and forces for aeroelastic problems on aerodynamic geometries.
    - SPOINT
      Bulk Data Entry Defines scalar points.
    - STACK
      Bulk Data Entry Defines the stacking information and stacking sequence for ply-based composite definition.
    - STEADY
      Bulk Data Entry Defines the combination of frequency response and linear static subcases used for steady state analysis.
    - SUPORT
      Bulk Data Entry Defines determinate reaction degrees-of-freedom in a free body.
    - SUPORT1
      Bulk Data Entry Defines determinate reaction degrees-of-freedom in a free body.
    - SURF
      Bulk Data Entry Defines a face of a shell or solid (3D solid, axisymmetric solid, or plane-strain solid) element as part of a surface.
    - SWLDPRM
      Bulk Data Entry Defines values of parameters used during the CWELD and CSEAM connectivity search.
    - TABDMP1
      Bulk Data Entry Defines modal damping as a tabular function of natural frequency.
    - TABDMP2
      Bulk Data Entry Defines modal damping as a tabular function of mode index.
    - TABFAT
      Bulk Data Entry Defines y values of each point on the loading time history.
    - TABLED1
      Bulk Data Entry Defines a tabular function for use in generating frequency-dependent and time-dependent dynamic loads.
    - TABLED2
      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.
    - TABLED3
      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.
    - TABLED4
      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.
    - TABLEG
      Bulk Data Entry Defines a general tabular function for use in supported reference entries.
    - TABLEM1
      Bulk Data Entry Defines a tabular function for use in generating temperature-dependent material properties.
    - TABLEM2
      Bulk Data Entry Defines a tabular function for use in generating temperature-dependent material properties. Also contains parametric data for use with the table.
    - TABLEM3
      Bulk Data Entry Defines a tabular function for use in generating temperature-dependent material properties. Also contains parametric data for use with the table.
    - TABLEM4
      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.
    - TABLEMD
      Bulk Data Entry Defines a multi-dimensional tabular function which identifies single or multiple X-values for a single Y-value.
    - TABLES1
      Bulk Data Entry Defines a tabular function for material and friction property.
    - TABLEST
      Bulk Data Entry Specifies the material property tables for elasto-plastic, temperature-dependent materials.
    - TABRND1
      Bulk Data Entry Defines power spectral density as a tabular function of frequency for use in random analysis. Referenced on the RANDPS entry.
    - TEMP
      Bulk Data Entry Defines temperature at grid points or a SET of grid points for determination of thermal loading and stress recovery.
    - TEMPADD
      Bulk Data Entry Defines a temperature set as a union of temperature sets defined via the TEMP or TEMPD Bulk Data Entries.
    - TEMPD
      Bulk Data Entry Defines a temperature value for all grid points of the structural model that have not been given a temperature on a TEMP entry.
    - TEMPP1
      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.
    - TEMPSEC
      Bulk Data Entry Defines temperature at grid points or a SET of grid points for determination of thermal loading on shell elements through thickness direction.
    - TEMPT
      Bulk Data Entry Defines parameters for mapping the grid temperature field from either an external file or an internal heat transfer subcase to either Nonlinear Static Analysis or Nonlinear Transient Analysis. The mapping is over time-domain only. The mapping is over time-domain only.
    - THIST
      Bulk Data Entry Defines the time history output request for Nonlinear Explicit Analysis.
    - TIC
      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.
    - TICA
      Bulk Data Entry Defines the initial velocity on a set of grids along and about an axis.
    - TIE
      Bulk Data Entry Defines a tied contact.
    - TLOAD1
      Bulk Data Entry Defines a time-dependent dynamic load or enforced motion.
    - TLOAD2
      Bulk Data Entry Defines a time-dependent dynamic excitation or enforced motion.
    - TRIM
      Bulk Data Entry Specifies the constraints for aeroelastic trim variables.
    - TSTEP
      Bulk Data Entry Defines time step parameters for control and intervals at which a solution will be generated and output in transient analysis.
    - TSTEPNL
      Bulk Data Entry Defines parameters for Nonlinear Direct Transient Analysis.
    - TSTEPE
      Bulk Data Entry Defines time step parameters for control and intervals at which a solution will be generated and output in explicit analysis.
    - UNBALNC
      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.
    - USET
      Bulk Data Entry Defines a set of degrees-of-freedom.
    - USET1
      Bulk Data Entry Defines a set of degrees-of-freedom.
    - VISCO
      Bulk Data Entry Defines parameters for nonlinear analysis involving time-dependent material behavior.
  - 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.

PARAM, HEX8ALT

Bulk Data Entry Controls an alternative formulation of 8-noded CHEXA element for linear analysis.


Parameter	Values	Description
`HEX8ALT`	<YES, NO>	YES Activates an alternative formulation using special bubble shape functions of 8-noded CHEXA elements for linear analysis. This helps improve accuracy for models with very coarse meshes. NO (Default) The traditional formulation is used for 8-noded CHEXA elements for linear analysis.