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Newton convergence could not be reached

Error

Newton convergence could not be reached. Possible options to prevent that behavior: Update the tangent matrix more often, increase the maximum number of iterations, use automatic timestepping or decrease the timestep.

What happened?

The solution diverged since no convergence could be reached under specific nonlinear Newton iterations.

What could be the possible reason?

This error may occur when solver failed to converge the solution under specific nonlinear Newton iterations while solving a nonlinear problem. The possible reason could be either the convergence criteria is quite strict or Maximum Newton iterations are to less to converge.

What can I do now?

To resolve this error, please do the following steps:

  • Increase the Tolerance of the convergence criteria under Numerics. For example, rather than 1e-6 give 1e-3. Please note, by doing this may result in less precise solution.

  • Increase Maximum Newton iterations under Numerics.

  • Update tangent or elastic matrix more often. For example, set Reactualisation every nth increment or Reactualisation every nth iterations to 1 rather than 3.

  • Use automatic Timestep definition rather than manual under Simulation Control.

Note

If none of the above suggestions did solve your problem, then please post the issue on our forum or contact us.