PSDCOM
PSDCOM, SIGNIF
, COMODE
, , ForceType
Specifies the power spectral density mode combination
method.
SIGNIF
Combine only those modes whose significance level exceeds the
SIGNIF
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 thanSIGNIF
is considered insignificant and is not contributed to the mode combinations. The higher theSIGNIF
threshold, the fewer the number of terms used.SIGNIF
defaults to 0.0001. IfSIGNIF
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 toNMODE
(input quantityNMODE
on the SPOPT command).COMODE
defaults toNMODE
.COMODE
performs a second level of control for the first sequentialCOMODE
number of modes to be combined. It uses the significance level threshold indicated bySIGNIF
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.