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Are there any tips for enhancing the convergence of a highly compressible foam with nonlinear contact against a rigid body? The Newton-Raphson force residual does not converge. Also, the contact agains the rigid body is over penetrating.

- January 25, 2023 at 7:34 am
  
  FAQ
  Participant
  
  In one particular application involving highly compressible ogden-foam with nonlinear contact, the Newton-Raphson force residual did not converge. Also, the penalty based contact produced a very low default stiffness value that caused over penetration. A few changes lead to converged solution with acceptable results. 1. Override the default Newton-Raphson force convergence tolerance with a fixed value. The default calculation was varying wildly. 2. Use Asymmetric Contact with Normal Lagrange Formulation and a generous Pinball Radius. The Lagrange formulation is often more challenging to converge, but in this partcular case, where the underlying material was so soft, Normal Lagrange actually proved to be much more stable. 3. Switch to lower order elements for added stability.

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