PSDCOM, SIGNIF
, COMODE
, , ForceType
Specifies the power spectral density mode combination
method.
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.
Label identifying the forces to be combined:
STATIC | — | Combine the modal static forces (default). |
TOTAL | — | Combine the modal static plus inertial forces. |