Reply To: fastener preload with random vibration or shock

[dlooman]

I agree with the idea behind what you say.  The nominal stress in the bolt doesn't change until the preload is exceeded.  Some people do a random vibration analysis just to see if the bolt will loosen, but typically vibration stresses in the bolt are very small.  It's not a bad idea to do a prestressed random vibration analysis after first loading and locking the bolt pretension forces though.  The contact definition is more accurate that way.