Load step inputs organize and manage the IDs of analysis parameter bulk cards.

## Nastran Cards

Card Description
ACSRCE Defines the power versus frequency curve for a simple acoustic source.
DLOAD Selects a dynamic load to be applied in a transient and frequency response analysis subcase. The DLOAD command can also be used to select a user-defined loading curve to be applied in a nonlinear static analysis subcase.
Note: Subcase Information Entry

EIGC Defines data needed to perform complex eigenvalue analysis
EIGRA Defines the data required to perform real eigenvalue analysis with the Automated Multi-Level Sub-structuring technique.
Note: Bulk Data Entry
EIGRL Defines data required to perform real eigenvalue analysis (vibration or buckling) with the Lanczos Method.
Note: Bulk Data Entry
NLPARM Activates nonlinear solution methods for this subcase and to select the parameters used for Nonlinear Quasi-static Analysis, Geometric Nonlinear Implicit Analysis, and Nonlinear Direct Transient Analysis.
Note: Subcase Information Entry
RGYRO 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.
Note: Bulk Data Entry
RLOAD1 Defines a frequency-dependent dynamic load of the form: $\left\{P\left(f\right)\right\}=\left\{A\right\}\left[C\left(f\right)+iD\left(f\right)\right]{e}^{i\left\{0-2\pi f\tau \right\}}$ for use in frequency response problems
RLOAD2 Defines a frequency-dependent dynamic excitation of the form: $\left\{P\left(f\right)\right\}=\left\{A\right\}\cdot B\left(f\right){e}^{i\left\{\varphi \left(f\right)+0-2\pi f\tau \right\}}$ for use in frequency response problems
TLOAD1 Defines a time-dependent dynamic load or enforced motion of the form:
$\left\{P\left(t\right)\right\}=\left\{A\cdot F\left(t-\tau \right)\right\}$
for use in transient response analysis
TLOAD2 Defines a time-dependent dynamic excitation or enforced motion of the form:
for use in a transient response problem, where: $\stackrel{˜}{t}=t-T1-\tau$

## OptiStruct Cards

Card Description
ACSRCE Defines acoustic source as a function of power vs. frequency.
Note: Bulk Data Entry
BASELIN Baseline correction
Note: Bulk Data Entry
EIGC Defines data required to perform complex eigenvalue analysis.
Note: Bulk Data Entry
EIGRA Defines the data required to perform real eigenvalue analysis with the Automated Multi-Level Sub-structuring technique.
Note: Bulk Data Entry
EIGRL Defines data required to perform real eigenvalue analysis (vibration or buckling) with the Lanczos Method.
Note: Bulk Data Entry
NLADAPT The NLADAPT entry can be used in the Subcase Information section to select the parameters used for Large Displacement Nonlinear Quasi-static Analysis, Small Displacement Nonlinear Quasi-Static Analysis, and Nonlinear Transient Analysis.
Note: Subcase Information Entry
NLENRG Energy variable output
NLMON This NLMON Subcase Information Entry can be used to activate Nonlinear Monitoring for a subcase by referencing a corresponding NLMON Bulk Data Entry.
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
NLPARM Activates nonlinear solution methods for this subcase and to select the parameters used for Nonlinear Quasi-static Analysis, Geometric Nonlinear Implicit Analysis, and Nonlinear Direct Transient Analysis.
Note: Subcase Information Entry
NLPRINT Controls printing message.
RGYRO 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.
Note: Bulk Data Entry
RLOAD1 Defines a frequency-dependent dynamic load of the form $\mathbf{f}\left(\Omega \right)=A*B\left(\Omega \right){e}^{i\left(\varphi \left(\Omega \right)+\theta -2\pi \Omega \tau \right)}$ for use in frequency response problems. RLOAD2 (Form 2) can be used when the frequency-dependent dynamic load input is available in magnitude/phase number format.
Note: Bulk Data Entry
RLOAD2 Specifies directional combination method, modal combination method, excitation direction(s), response spectra and scale factors.
Note: Bulk Data Entry