Is it possible to use submodelling in a PSD analysis?
In general, no, you can't specify the cut boundary displacements
from a PSD analysis on a submodel, because they are statistical
quantities (1 sigma) values. However, it would be possible to use the RPSD
from a PSD analysis as the base excitation of a "submodel" that is cantilevered
off the original model. The submodel analysis would be another PSD analysis
and not a static analysis as is usual with submodeling.