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Material Damge Model

    • J.Benavides

      Hi, I need to replicate in Ansys APDL a simulation carried out in Abacus. For AS235 Steel material, the following simulation was carried out on a structure consisting of 2 plates separated by a certain distance and subjected to an impact. I must recreate the material damage simulation (See Photo). I have an uniaxial test of the material as data, I know that with this I could use a multilinear isotropic hardening curve up to plastic deformation without damage, but then I don't know how to represent the behavior after that, until the material breaks (the breakage of the material).   Can someone help me or give me some guidance? Thank you for any help. 

    • Bill Bulat
      Ansys Employee

      Was this analysis performed with Abaqus Explicit?

      MAPDL technology is strictly implicit. Even if we "kill" (deactivate) elements (using the MAPDL EKILL command) as the solution progresses (using, say, some kind of limiting stress as a criterion for element deactivation), the deactivated elements are retained... they will continue to be used in the formulation of the system matrices. The failed elements will almost certainly become "entangled" - it will be impossible to formulate global stiffness matrix based on severely mishapen elements (e.g., vertices get pushed though element faces/edges on the opposite side). When that happens it's game over - the simulation will end with an element formulation error.

      We have a couple of explicit solvers that are almost always much better suited to an impact + ultimate failure simulation such as this. They allow the specification of limiting failure stresses which, when exceeded, result in the elimination of the element entirely (so the simulation can proceed).

    • J.Benavides


      Thank you very much for your quick answer.

      Yes, the simulation was performed with an explicit time integration, a quasi-static simulation. As additional information, can I mention that for the material model they use a hardening power of low for the plastic regime and a polynomial curve as function of plastic deformation for the damage evolution.

      For the ansys MAPDL I already defined the impact through a contact pair and for the plate (Indenter: target 170 and contact surface: conta 174 elements) I use a shell element (shell 181) and for the material model I will define a multilinear isotropic hardening curve from the material data for the plastic regime but for the damage evolution and to generate the breaking of the steel plate, I don't know how it proceeds.

      Which explicit solvers could I use to do this? I would really appreciate your help.

      Thank you.




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