The Fast PSD Response object under the Fast Dynamic Response add-on provides a spectrum response for a structural component subjected to random excitation. PSD Response is plotted as square of spectrum response over the excitation frequency range. The plot provides information as to where the average power is distributed as a function of frequency. The square root of the area under the response is the so-called root-mean-square (RMS) value. In statistical terms it is a one-sigma, or one-standard-deviation, value.
This result object leverages precomputed modal analysis results, specifically modal participation factors, natural frequencies, and mode shapes. It uses these to compute the following results under a Power Spectral Density (PSD) load, without requiring a full random vibration analysis.
Force and Moment Reactions
Stress and Strain (Normal, Shear and von-Mises)
You can provide the PSD input, typically acceleration or base excitation in the frequency domain, and the tool combines this with modal data to estimate the response spectrum. This allows efficient estimation of the results listed above under stochastic dynamic loading with significantly reduced computational effort compared to a full transient or random vibration solution.