The following PowerPoint is from one of PADT’s inhouse experts on linear dynamics, Alex Grishin.
One of the most valuable results that can come from a harmonic response analysis is the predicted alternating stresses in the part. This feeds fatigue and other downstream calculations as well as predicting maximum possible values. Because of the math involved, calculating derived stresses, like Principal Stresses and von Mises Stress can be done in several ways. This post shows how Ansys Mechanical does it and offers an alternative that is considered more accurate for some cases for von Mises. Part 1 covers how to do the same for Principal Stresses.
Alex also made this zip file that contains updated macros, an example Mechanical database, and a spreadsheet: