PSDCOM

PSDCOM, SIGNIF, COMODE, , ForceType
Specifies the power spectral density mode combination method.

Valid Products: Pro | Premium | Enterprise | PrepPost | Solver | AS add-on

SIGNIF

Combine only those modes whose significance level exceeds theSIGNIF threshold. For PSD response (SPOPT,PSD), the significance level is defined as the modal covariance matrix term, divided by the maximum modal covariance matrix term. Any term whose significance level is less than SIGNIF is considered insignificant and is not contributed to the mode combinations. The higher the SIGNIF threshold, the fewer the number of terms used. SIGNIF defaults to 0.0001. If SIGNIF is specified as 0.0, it is taken as 0.0.

COMODE

First COMODE number of modes to be actually combined. COMODE must always be less than or equal to NMODE (input quantity NMODE on the SPOPT command). COMODE defaults to NMODE. COMODE performs a second level of control for the first sequential COMODE number of modes to be combined. It uses the significance level threshold indicated by SIGNIF and operates only on the significant modes.

ForceType

Label identifying the forces to be combined:

STATIC

 — 

Combine the modal static forces (default).

TOTAL

 — 

Combine the modal static plus inertial forces.

Notes

This command is also valid for PREP7. This command is valid only for SPOPT,PSD.

Menu Paths

Main Menu>Preprocessor>Loads>Load Step Opts>Spectrum>PSD>Mode Combine
Main Menu>Solution>Load Step Opts>Spectrum>PSD>Mode Combine