Is it possible to plot principal stresses from a PSD (random vibration) analysis?
In newer releases of Ansys, it is not possible to plot principal stresses from a PSD analysis. The capability to plot principal stresses from a PSD analysis was removed in Release 8.1.
The stress components from PSD analyses are 1-sigma results, so they do not have an associated sign. Using these statistical stress components to calculate derived stress quantities is not appropriate. The equivalent stress (SEQV) is determined using the Segalman-Reese approach, which considers the probability distribution of equivalent stress. The Segalman-Reese approach does not cover principal stresses.