Non Linear Fixtures/Contacts

Hi All,

I'm having trouble getting results I feel are plausible running a non linear shock simulation.

I have essentially a metal box with lots of components inside. In operation, the box mounts to a flat rigid panel that will undergo pyro shock loading. The box mounting surface is planer with four 'ears' with clearance holes. I have tried a couple different simulation strategies neither of which gives me a warm fuzzy.

One method is that I simply used the through hole and washer bearing surface (as a split line) as fixed.

For the second method, I mated my metal box to a flat plate with a relief everywhere except where the ears are. I also added screws and washers. This method resulted in very high stress where the ears meet the edge of the relief. This is clearly not real life.

Both methods result in deformed mode shapes where the box would penetrate the mounting plate which clearly isn't possible.

I wish I could use a virtual wall with non linear studies as that how this would behave in real life.

How would you guys approach this problem?

Thanks,

Kevin