Problem : big element deformation

Hi,

 

I modelize an impact of a rigid body on a very soft object (Young modulus = 1 MPa). I am doing a test convergence on mesh size. I have 3 models of different mesh size.

With the 4mm model mesh size, the computation goes well. But for the other models, the computation stops (negative volume) or there is a problem with some elements at the contact interface (see attached file).

I use TYPE 7 Contact interface. I have tested different parameters (default, advised...) but always the same problem.

For the element formulation, I use HEPH (Isolid = 24).

Do you have an idea of what could be the reason of my problem ?

 

Thank you for your asnwers,

 

Benjamin

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