Ansys Learning Forum Forums Discuss Simulation General Mechanical Solution combination for Random vibration and Static Structural Reply To: Solution combination for Random vibration and Static Structural

dlooman
Ansys Employee

If you are not using the PSD for a fatigue analysis (the more normal case) and simply want to do an allowable stress evaluation then I think it is reasonable to add the static stresses to the 3 sigma PSD stresses.  There is still the issue that negative static stresses will cancel out the unsigned 3 sigma stresses.  If there was a way to combine the absolute value of the static stresses with the 3 sigma stresses that would be more correct.  That's a feature of APDL POST1 load case combinations.  Some industries do treat the 3 sigma stress as an upper bound (which technically it isn't.)