Load Steps

Load step entities define and store load cases for a given analysis.

Load steps are defined by selecting associated load collectors and output blocks.

Abaqus Cards

A load step corresponds to a *STEP definition in Abaqus model history. Load collectors, output blocks and groups within a load step are exported under the corresponding *STEP block in the Abaqus input deck.

Card	Description
*ADAPTIVE MESH	Defines an adaptive mesh domain and specifies the frequency and intensity of adaptive meshing for that domain. Note: Defined in the load step card image.
*BUCKLE	Obtain eigenvalue buckling estimates. Note: Defined in the load step card image.
*BULK VISCOSITY (Explicit)	Modify bulk viscosity parameters. Note: History data.
*CONTACT STABILAZATION	Used to define the stabilization for general contact. Note: Defined in the load step card image.
*COUPLED TEMP-DISPLACEMENT	Analyze problems where the simultaneous solution of the temperature and stress/displacement fields are necessary. Note: Defined in the load step card image.
*COUPLED THERMAL-ELECTRICAL	Multiphysics loadstep for thermal and electrical analysis. Note: Defined in the load step card image.
*DYNAMIC (Explicit)	Dynamic stress/displacement analysis. Note: Defined in the load step card image.
*DYNAMIC (Standard)	Dynamic stress/displacement analysis. Note: Defined in the load step card image.
*FILE FORMAT	Specify format for results file output and invoke zero-increment results file output. Note: Defined in the load step card image.
*FREQUENCY	Extract natural frequencies and modal vectors. Note: Defined in the load step card image.
*GEOSTATIC	Verify that the geostatic stress field is in equilibrium with the applied loads and boundary conditions on the model and to iterate, if needed, to obtain equilibrium.
*HEAT TRANSFER	Transient or steady-state uncoupled heat transfer analysis. Note: Defined in the load step card image.
*LOAD CASE	Begin a load case definition for multiple load case analysis. Note: Defined in the load step card image.
*MODAL DYNAMIC	Dynamic time history analysis using modal superposition Note: Defined in the load step card image.
*MONITOR	Define a degree of freedom to monitor. Note: Defined in the load step card image.
*PRINT	Request or suppress output to the message file in an Abaqus/Standard analysis or to the status file in an Abaqus/Explicit analysis. Note: Defined in the load step card image.
*RADIATION_ VIEWFACTOR	Control the calculation of viewfactors during a cavity radiation analysis. Note: Defined in the load step card image; visible in *Heat Transfer analysis procedure.
*RESPONSE SPECTRUM	Calculates estimates of peak values of nodal and element responses. Note: Defined in the load step card image.
*RESTART WRITE	Save and reuse data and analysis results. Note: Defined in the load step card image.
*STATIC	Static stress/displacement analysis. Note: Defined in the load step card image.
*STEADY STATE DYNAMICS	Steady-state dynamic response based on harmonic excitation. Note: Defined in the load step card image.
*STEADY STATE TRANSPORT	Note: Defined in the load step card image.
*STEP	Begin a step. Note: Parameters are defined in the load step card image.
*VISCO	Transient, static, stress/displacement analysis with time-dependent material response (creep, swelling, and viscoelasticity) Note: Defined in the load step card image.

ANSYS Cards

Card	Description
ACEL	Specifies the linear acceleration of the structure.
ANTYPE	Specifies the analysis type and restart status.
CECMOD
CMACEL	Specifies the translational acceleration of an element component.
CMDOMEGA	Specifies the rotational acceleration of an element component about a user-defined rotational axis.
CMOMEGA	Specifies the rotational velocity of an element component about a user-defined rotational axis.
EQSLV	Specifies the type of equation solver.
LSSOLVE	Reads and solves multiple load steps.
NLGEOM	Includes large-deflection effects in a static or full transient analysis.
NSUBST	Specifies the number of substeps to be taken this load step.
OMEGA	Specifies the rotational velocity of the structure.
OUTRES	Controls the solution data written to the database.
TIME	Sets the time for a load step.

Nastran Cards

Load step entities directly correspond to Nastran subcase definitions.

Load steps can reference constraint (SPC), static load (LOAD), multi-point constraint (MPC), fictitious support (SUPORT1), non-linear parameters (NLPARM), eigenvalue extraction data (METHOD), frequency range (FREQ), damping (SDAMPING), dynamic load (DLOAD), thermal loading (TEMP), and so on subcase definitions. Other input data is automatically generated (the SUBCASE header) or may be added to the subcase definition.

Card	Description
ANALYSIS	Used in the I/O Options section to request that only a finite element analysis be performed (optimization input is ignored). It may also be used in the I/O Options or Subcase Information sections to identify the solution sequence for all subcases or for individual subcases, respectively. The remaining options refer to the solution sequence identification functionality of the ANALYSIS command: STATICS Linear Static or Nonlinear Quasi-Static Gap Analysis NLSTAT Small Displacement Nonlinear Analysis MODES Normal Modes Analysis MCEIG Modal Complex Eigenvalue Analysis BUCK Linear Buckling Analysis DFREQ Direct Frequency Response Analysis MFREQ Modal Frequency Response Analysis DTRAN Direct Transient Response Analysis (Linear and Nonlinear) MTRAN Modal Transient Response Analysis DFOUR Direct Transient Response Analysis through Fourier transformation. MFOUR Model Transient Response Analysis through Fourier transformation. HEAT Linear Steady-State Heat Transfer Analysis or Linear Transient Heat Transfer Analysis NLHEAT Nonlinear Steady-State Heat Transfer Analysis, or Nonlinear Transient Heat Transfer Analysis. MBD Multibody Dynamics Analysis EXPDYN Geometric Nonlinear Explicit Dynamic Analysis FATIGUE Fatigue Analysis RANDOM Random Response Analysis Note: Subcase Information Entry Enable the subcase option ANALYSIS and then select an analysis type.
ANALYSIS Type	Subcase selections will displayed based on the analysis type selected. ANALYSIS I/O option with type is set in Subcase options. Note: I/O Options Entry
BCONTACT	This entry is used to initiate and control which bodies come into contact in SOLs 101, 400.
CMETHOD	The CMETHOD command can be used in the Subcase Information section to select the method for complex eigenvalue extraction. Note: Subcase Information Entry
DEFORM	The DEFORM command can be used in the Subcase Information section to select an element deformation set. Note: Subcase Information Entry
FREQUENCY	Selects the set of forcing frequencies to be solved in a frequency response problem. Note: Subcase Information Entry Enables you to select load collectors with frequency information (FREQ, FREQ1, FREQ2, FREQ3, FREQ4, FREQ5).
IC	Selects initial conditions for Transient and Explicit Analysis.
LABEL	Provides a subcase with a label. Note: Subcase Information Entry
LOAD	Selects a static load set to be applied in linear static solutions. Note: Subcase Information Entry Enables you to select load collectors with static load information (FORCE, MOMENT, PLOAD, PLOAD2, PLOAD4, LOAD), or inertial loading information (GRAV, RFORCE).
METHOD	Selects a method for real eigenvalue extraction. Note: Subcase Information Entry Select load collectors with an EIGRL card image for METHOD(STRUCT) or METHOD(FLUID).
MFLUID	Selects the MFLUID Bulk Data entries to be used to specify the fluid-structure interface Note: Bulk Data Entry
MPC	Selects a multi-point constraint set. Note: Subcase Information Entry
NLOUT	The NLOUT entry can be used in the Subcase Information section to select the incremental result output parameters used for Nonlinear Static Analysis and Nonlinear Transient Analysis. Note: Subcase Information Entry
NLSTEP	Describes the control parameters for mechanical, thermal and coupled analysis in SOL 400 and for linear contact analysis in SOL 101.
NONLINEAR	The NONLINEAR command can be used in the Subcase Information section to select a nonlinear dynamic load set for direct transient analyses Note: Subcase Information Entry
RSDAMP	Requests parameter and hybrid damping for the residual structure.
SDAMPING	Applies modal damping as a function of natural frequency in modal solutions. Note: Subcase Information Entry
SPC	Selects a single-point constraint set. Note: Subcase Information Entry
STATSUB	Selects a static solution subcase. Note: Subcase Information Entry
SUBCASE	Indicates the start of a new subcase definition. Note: Subcase Information Entry
SUBCOM	Defines a combination subcase. Note: Automatically created when a new load step of type “Combination Subcase Delimiter” is created. The SUBCOM ID matches the ID of the HyperMesh load step entity.
SUBSEQ	Subcase sequence coefficients. Note: Only available for Combination Subcase Delimiter load steps. Enable SUBSEQ to input combination coefficients.
SUBTITLE	Defines the subtitle for all subcases or for individual subcases, respectively.
SUPORT1	Selects a fictitious support set to be applied to the model. Note: Subcase Information Entry
TEMP	Defines temperature at grid points or a SET of grid points for determination of Thermal Loading and Stress recovery.
TITLE	Defines a character string to appear on the first heading line of each page of MSC Nastran printer output.
TRIM	Selects trim variable constraints in static aero-elastic response.
TSTEP	Selects integration for transient analysis. Note: Subcase Information Entry
TSTEPNL	Defines parametric controls and data for nonlinear transient structural or heat transfer analysis.

OptiStruct Cards

Loadsteps directly correspond to OptiStruct subcases. Load steps can reference static loads (LOAD), constraints (SPC), and dynamic loads (DLOAD).

Supported card parameters are dependent upon the selected analysis type (solution sequence).

Card	Description
ACCELERATION	Requests acceleration vector output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select ACCELERATION.
ANALYSIS	Used in the I/O Options section to request that only a finite element analysis be performed (optimization input is ignored). It may also be used in the I/O Options or Subcase Information sections to identify the solution sequence for all subcases or for individual subcases, respectively. The remaining options refer to the solution sequence identification functionality of the ANALYSIS command: STATICS Linear Static or Nonlinear Quasi-Static Gap Analysis NLSTAT Small Displacement Nonlinear Analysis MODES Normal Modes Analysis MCEIG Modal Complex Eigenvalue Analysis BUCK Linear Buckling Analysis DFREQ Direct Frequency Response Analysis MFREQ Modal Frequency Response Analysis DTRAN Direct Transient Response Analysis (Linear and Nonlinear) MTRAN Modal Transient Response Analysis DFOUR Direct Transient Response Analysis through Fourier transformation. MFOUR Model Transient Response Analysis through Fourier transformation. HEAT Linear Steady-State Heat Transfer Analysis or Linear Transient Heat Transfer Analysis NLHEAT Nonlinear Steady-State Heat Transfer Analysis, or Nonlinear Transient Heat Transfer Analysis. MBD Multibody Dynamics Analysis EXPDYN Geometric Nonlinear Explicit Dynamic Analysis FATIGUE Fatigue Analysis RANDOM Random Response Analysis Note: Subcase Information Entry Enable the subcase option ANALYSIS and then select an analysis type.
ANALYSIS Type	Subcase selections will displayed based on the analysis type selected. ANALYSIS I/O option with type is set in Subcase options. Note: Subcase Information Entry
ASSIGN	Used in the I/O Options section to identify external files and their contents. Note: I/O Options Entry
CMSMETH	Requests that only a component mode synthesis solution be performed and to select a component mode synthesis method definition to be used. Note: Subcase Information Entry
CMETHOD	The CMETHOD command can be used in the Subcase Information section to select the method for complex eigenvalue extraction. Note: Subcase Information Entry
CNTNLSUB	The CNTNLSUB command can be used in the Subcase Information section to continue a nonlinear solution from a preceding nonlinear subcase, and thus create complex loading sequences Note: Subcase Information Entry
CNTSTB	The CNTSTB command can be used in the Subcase Information section to activate stabilization of surface-to-surface (S2S) contact and large displacement node-to-surface (N2S) contact for this subcase. It is used only for Small Displacement Nonlinear Analysis. Note: Subcase Information Entry
CONVG	Can be used in the Subcase Information section to select a corresponding CONVG Bulk Data Entry. Note: Subcase Information Entry
CSTRAIN	Requests ply strain output for elements referencing PCOMP, PCOMPP or PCOMPG properties for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select CSTRAIN.
CSTRESS	Requests ply stress output for elements referencing PCOMP, PCOMPP or PCOMPG properties for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select CSTRESS.
DEFORM	The DEFORM command can be used in the Subcase Information section to select an element deformation set. Note: Subcase Information Entry
DESOBJ	Selects a single response definition as the objective function of an optimization, or to select system response definitions when the objective function is the least squares sum of these definitions. The DESOBJ command also indicates if this response is to be minimized or maximized. Note: Subcase Information Entry Part of the optimization problem setup, created when you define an objective.
DESSUB	Used within a subcase definition, to select a constraint set that is subcase dependent. Note: Subcase Information Entry Part of the optimization problem setup, created when you define a dconstraint.
DISPLACEMENT	Requests displacement vector output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select DISPLACEMENT.
EIGRD	Defines data required to perform eigenvalue extraction using the Lapack-based dense solver. Note: Bulk Data Entry
EIGVRETRIEVE	Retrieves eigenvalue and eigenvector results of a Normal Modes Analysis from an external data file (.eigv). Note: Subcase Information Entry
EIGVSAVE	Outputs eigenvalue and eigenvector results of a Normal Modes Analysis to an external data file (.eigv). Note: Subcase Information Entry
ELFORCE	Requests structural element force output and elemental fluid particle velocity output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select ELFORCE.
ENDLOAD	The ENDLOAD command can be used in the I/O Options or Subcase Information sections to request End Load output for all edges for relevant subcases or individual subcases respectively. Note: I/O Options and Subcase Information Entry
ERP	Requests equivalent radiated power output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select ERP.
ESE	Requests strain energy and strain energy density output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select ESE.
EXCLUDE	Selects a set of elements to be excluded from a Linear Buckling Analysis. Enable the subcase option OUTPUT to select EXCLUDE, then select a SET definition. Note: Subcase Information Entry Enable the subcase option OUTPUT to select EXCLUDE, then select a SET definition.
FATDEF	Selects a FATDEF Bulk Data Entry that will define the elements, and their associated fatigue properties, to be considered for Fatigue Analysis. Note: Subcase Information Entry
FATPARM	Selects a FATPARM Bulk Data Entry that will define the parameters to be used for a Fatigue Analysis. Note: Subcase Information Entry
FATSEQ	Indicates that a subcase is a fatigue analysis subcase and to select a FATSEQ Bulk Data Entry that will define the loading sequence for the Fatigue Analysis. Note: Subcase Information Entry
FLLWER	The FLLWER command can be used in the Subcase Information section to activate updating the node forces introduced by a pressure load. Note: Subcase Information Entry
FREQUENCY	Selects the set of forcing frequencies to be solved in a frequency response problem. Note: Subcase Information Entry Enables you to select load collectors with frequency information (FREQ, FREQ1, FREQ2, FREQ3, FREQ4, FREQ5).
FSI	Identifies a FSI Bulk Data Entry to run Fluid-Structure Interaction Analysis with Altair AcuSolve for a Linear Transient Heat Transfer Subcase or Nonlinear Direct Transient Analysis Subcase. Note: Bulk Data Entry
GLOBSUB	Selects a subcase that references the global structure for Local-Global Analysis and a set of grid points in the local structure that defines the cut surface for displacement. Note: Subcase Information Entry
GPFORCE	Requests grid point force balance output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select GPFORCE.
GPSTRESS	Requests grid point stresses output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select GPSTRESS.
IC	Selects initial conditions for Transient and Explicit Analysis. Note: Subcase Information Entry
INVEL	Selects a multibody initial velocity set to be applied in a multibody problem. Note: Subcase Information Entry
JOULE	Used in a heat transfer (steady-state/transient, linear/nonlinear) subcase. Note: Subcase Information Entry
LABEL	Provides a subcase with a label. Note: Subcase Information Entry
LOAD	Selects a static load set to be applied in linear static solutions. Note: Subcase Information Entry Enables you to select load collectors with static load information (FORCE, MOMENT, PLOAD, PLOAD2, PLOAD4, LOAD), or inertial loading information (GRAV, RFORCE).
LOADJG	Used in the Subcase Information section to select a load set to be applied to joints which are defined via the JOINTG Bulk Data Entry. Note: Subcase Information Entry
MBSIM	Selects a Multibody simulation definition to be applied in a Multibody problem. Note: Subcase Information Entry
METHOD	Selects a method for real eigenvalue extraction. Note: Subcase Information Entry Select load collectors with an EIGRL card image for METHOD(STRUCT) or METHOD(FLUID).
MFLUID	Selects the MFLUID Bulk Data entries to be used to specify the fluid-structure interface Note: Bulk Data Entry
MLOAD	Selects a Multibody load set to be applied in a Multibody problem. Note: Subcase Information Entry Enables you to select load collectors with multi-body dynamic load information (GRAV, MBFRC, MBFRCC, MBMNT, MBMNTC, MLOAD).
MODCHG	The MODCHG command can be used to remove and/or reactivate contact interfaces and/or elements for this subcase. It is used only for nonlinear analysis. Note: Subcase Information Entry
MODESELECT	The MODESELECT command can be used in the I/O Options or the Subcase Information section to select a subset of computed modes in modal dynamic analysis subcases. Note: I/O Options or Subcase Information Entry
MODEWEIGHT	Defines a multiplier for computed eigenvalues that are to be used in the calculation of the "weighted reciprocal eigenvalue" and "combined compliance index" optimization responses. Note: Subcase Information Entry Part of the optimization problem setup, created when you define a response.
MOTION	Selects a Multibody motion set to be applied in a multibody problem. Note: Subcase Information Entry Enables you to select load collectors with multi-body dynamic motion information (MOTION, MOTNG, MOTNGC).
MOTNJG	Used to select the motion applied to corresponding joints. Note: Subcase Information Entry
MPC	Selects a multi-point constraint set. Note: Subcase Information Entry
MPCFORCE	Requests multi-point force of constraint vector is output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry
NLOAD	The NLOAD command can be used in the Subcase Information section to select a time dependent load to be applied in Explicit Dynamic Analysis problem. Note: Subcase Information Entry
NSM	Selects a non-structural mass set for mass generation. The selector command must appear before the first SUBCASE statement. Note: Subcase Information Entry
OFREQUENCY	Requests a set of frequencies for output requests for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select OFREQUENCY.
OLOAD	Requests the form of applied load vector output and temperature load output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select OLOAD.
OMODES	Requests a set of modes for output requests for all subcases or for individual subcases, respectively. This command is applicable for normal modes and linear buckling solution sequences only. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select OMODES.
PEAKOUT	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. Note: Subcase Information Entry
PFGRID	Requests output of acoustic grid participation factors for all Modal Frequency Response subcases. The output will be in the .h3d file. Note: I/O Options Entry
PFMODE	Requests output of modal participation factors for all modal frequency response subcases. Note: I/O Options Entry
PFPANEL	Requests output of acoustic panel participation factors for all Modal Frequency Response subcases. Note: I/O Options Entry
POST	Used to request subcase-specific output to separate files. Note: Subcase Information Entry
PRETENSION	The PRETENSION command can be used in the Subcase Information section to select and activate a pretensioning bolt load. Note: Subcase Information Entry
RADSND	The RADSND command can be used in the Subcase Information section to select RADSND Bulk Data to specify sound generation panels and microphone field locations. Note: Subcase Information Entry
RANDOM	Selects the RANDPS and RANDT1 Bulk Data Entries to be used in Random Response Analysis. Note: Bulk Data Entry
REQUEST	Selects a multibody request definition to be used in a multibody problem. Note: I/O Options Entry
RESVEC	Controls the calculation of residual vectors. Note: Subcase Information Entry
RSPEC	References combination rules, excitation degrees-of-freedom, and input spectra for use in response spectrum analysis. Note: Subcase Information Entry
RWALL	Selects rigid walls for geometric nonlinear analysis. Note: Subcase Information Entry
SDAMPING	Applies modal damping as a function of natural frequency in modal solutions. Note: Subcase Information Entry
SOLVTYP	Defines the solver type to be used for static, dynamic analysis and geometric nonlinear implicit analysis. Note: Bulk Data Entry
SPC	Selects a single-point constraint set. Note: Subcase Information Entry
SPCFORCES	Requests single-point force of constraint vector output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry
STATSUB	Selects a static solution subcase. Note: Subcase Information Entry
STRAIN	Requests strain output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select STRAIN.
STRESS	Requests stress output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select STRESS.
SUBCASE	Indicates the start of a new subcase definition. Note: Subcase Information Entry
SUBCOM	Delimits and identifies a combination subcase. Note: Subcase Information Entry
SUBMODEL	Selects a submodel as a set of elements. Subcase entries specific to the selected element set can be used to solve the submodel without affecting the rest of the structure. Note: Subcase Information Entry
SUBSEQ	Gives the coefficients for forming a linear combination of the previous static subcases. Note: Subcase Information Entry
SUBTITLE	Defines the subtitle for all subcases or for individual subcases, respectively.
SUPORT1	Selects a fictitious support set to be applied to the model. Note: Subcase Information Entry
TEMP	Defines temperature at grid points or a SET of grid points for determination of Thermal Loading and Stress recovery.
TSTEP	Selects integration for transient analysis. Note: Subcase Information Entry
TTERM	Used in a geometric nonlinear subcase to define the termination time. Note: I/O Options and Subcase Information Entry
VELOCITY	Requests velocity vector output for all subcases or individual subcases, respectively. Note: I/O Options and Subcase Information Entry Enable the subcase option OUTPUT to select VELOCITY.
WEIGHT	Defines a weighting factor (multiplier) for the compliances of individual linear static solution subcases, which are used in the calculation of the "weighted compliance" and "combined compliance index" optimization responses. Note: Subcase Information Entry
XHIST	Selects time history output for geometric nonlinear analysis. Note: Subcase Information Entry

Permas Cards

Card	Description
$CONSTRAINTS	Constraint variant bracket header line. Note: Set AnalysisProcedure to CONSTRAINTS.
$FREQLOAD	Definition of frequency dependent dynamic loads for use in frequency response analysis. Note: Only available when AnalysisProcedure is set to LOADING.
$LOADING	Loading variant bracket header line. Note: Set AnalysisProcedure to LOADING.
$NLLOAD	Define a nonlinear static load history. Note: Only available when AnalysisProcedure is set to LOADING.
$SITUATION	Situation definition header line. Note: Set AnalysisProcedure to SITUATION.
$TRANSLOAD	Definition of time dependent dynamic loads for use in transient response analysis. Note: TRANSLOAD cards and FREQLOAD cards are mutually exclusive.