A Random Vibration node (
) defines a random vibration analysis based on a frequency response model, primarily for structural mechanics simulations. This feature makes it possible to postprocess the probability spectral density (PSD) of a Frequency Domain, Modal Reduced-Order Model’s response to random loads described by their power spectra. The output is presented using two operators,
<rom_name>.
psd(...) and
<rom_name>.
rms(...), where
<rom_name> is the
Name of the Random Vibration node. For details, see
Performing a Random Vibration Analysis in the
Structural Mechanics Module User’s Guide.
The Settings window for a
Random Vibration node contains the following sections:
From the Frequency response model list, choose an existing
Frequency Domain, Modal Reduced-Order Model node representing the frequency-domain behavior of the structure.
From the Correlation type list, choose a type of correlation:
Uncorrelated (the default),
Fully correlated, or
Cross-correlated. If you choose
Cross-correlated, a correlation matrix appears at the bottom of this section.
For each reduced-order model input used in the selected Frequency response model, and displayed in the
Control name list, enter an input
Power spectral density expression. Note that this expression is usually a function of the frequency,
freq.
If the correlation type was set as Cross-correlated, fill in expressions for the off-diagonal elements of the cross-correlation between the reduced-order model inputs. These expressions are also typically frequency dependent.