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Nonlinear Indention Simulation in CW2008

Question asked by Eric Hill on Feb 5, 2009
Latest reply on Feb 7, 2009 by Bill McEachern
I am trying to use COSMOS 2008 Adv Pro to model a flat indentor pushing into a semi-infinite plane of a relatively soft material. The load on the indentor is high enough to yield the soft material in the plane, which leaves behind a permanent impression in the soft material when the indentor is withdrawn. As an output of the analysis, I would like to produce a load-displacement curve for the indenting operation.

The indentor material is a linear elastic material with a high elastic modulus. The soft plane material is a non-linear with a defined stress-strain curve that looks like a classic plastically deforming metal. The yield strength of the plane material is significantly below the indentor's yield strength.

My non-linear static model behaves well thoughout the elastic range, but when the plastic deformation becomes significant, the simulation diverges and the solver chokes.

Is this typical behavior for COSMOS Non-linear when dealing with these sorts of problems? It's my interpretation that the simulation runs smoothly until the deformation of mesh in the soft material is big enough that the deformation of the mesh elements reaches some critical value. I've seen some papers describing using FEA to simulate this type of phenomenon, but non using any of the COSMOS products.

Please let me know if you have any experience with running this type of simuation. Your input will be much appreciated.