Solution 788621 mentions using load case combinations to get the total stress in a pre-stressed harmonic response analysis. Do you have any examples?

Yes, please see the attached ANSYS 11.0 SP1 example. However, please note that the amplitude is always positive, so a bending beam gives positive maximum stress on both the top AND bottom of the beam at the same time. This is not realistic, but if all that you want is the single highest stress at a natural frequency for a prestressed structure, the very worst stress should be found (like at the root of a fillet weld).

However, a more realistic approach would be to take the stresses at each angle (say every five degrees) for each frequency of interest and add or subtract them from the static solution stresses to get a better feel for what is going on. Alternatively, you can run a full transient and apply a load that is harmonic in nature and after several cycles, you should get an idea of what to use.

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