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.