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Bonded Bodies Overlap During Drop Test

Question asked by Mark Smith on Jul 28, 2011
Latest reply on Aug 11, 2011 by Mark Smith

After running a drop test simulation on a an assembly, surfaces that have Bonded contact sets intersect and thus show significant differences in resulting displacement.

 

More detail:

I designed a plastic part with a stainless steel bracket (spine) insert molded into the part to add strength during drop.  In terms of modelling, the SS bracket was inserted into the part in an assembly, and then I used the Cavity feature to shell out the plastic part in the geometry of the bracket.  As shown below:

 

Pre-Drop Test Model.JPG

 

All the surfaces are contacting each other between the bracket and the plastic housing surrounding it, so I added Bonded contact sets to each of the surfaces.

After running the drop test, the deformed model of the view above looks like this:

Overlapping Bodies.JPG

Why are the bodies overlapping?  The Von Mises stress is well below the yield points for both the plastic and SS.  Maybe I'm missing something simple.

 

*Note that I also ran the exact same drop test changing the Bonded contact sets to No Penetration.  This alleviated the overlapping body issue, but the resulting Von Mises stresses were literally 15 times greater than the same test with Bonded contacts.

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