Reply To: fastener preload with random vibration or shock

[Dennis Chen]

 

I had dealt with this same issue at work many months ago.   Just as Dave Looman up there said (Hi Dave), nominal stress on the bolt does not change until preload is exceeded.   in addition, shock/random vibe are linear dynamic analysis which means we cannot model contact separations (contact nonlineraity). 

The key to simulation is to have a clear objective and understand the limitations of the method with respect to that objective.   It’s hardly “conservative” to add shock induced stress on top of preload induced stress to calculate max load, I think it’s straight-up incorrect.   that’s my opinion at least.