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Arun S

Model Penetrates Master Surfaces during simulation

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I am trying to model deformation of foam in Optistruct (Non linear quasi static, NLSTAT subcase) by imposing displacement of top plate through the foam and constraining the bottom plate.


Though my model is converging, you can see the foam penetrates the bottom plate (green).


Three contacts have been defined in the model, 1) Top plate (Prop) and Foam (Nodes) with PCONT/PCONTX7  2) Side plate (Prop) and Foam (Prop) with Static Fric and 3) Bottom plate (Prop) and Foam (Prop) with Static Fric. (Master and Slave order being followed).


Can you suggest a way to overcome this problem?




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Hi @Arun S


I think the problem is coming from the way the contacts are defined.


I see that you have selected all foam nodes for all contacts and this is diverging the results.


Try this:


Only select those nodes which come in contact with the bottom, side and top faces of solid elements and check if you see any improvement in results. 

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Hi Prakash,


I did include only the nodes which contact the bottom,top and side plates, but ended up with the same results after the simulations.


These additional nodes displaced during compression, reaches the bottom plate and penetrates through irrespective of the contact definition. Any thoughts?






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Hi Arun,


I tried with freeze and the runs fine with Freeze.


I would suggest to try with slide contact without friction and then you add friction based on the response. 


Also, it looks like a large strain problem, so the results from NLSTAT may not be right. Use NLSTAT with LGDISP to run large strain non linear problems. 



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