Reply To: Convergence problems in very large deformations: Neo-Hookean hyperelastic model.

[John Doyle]

Perhaps you need a lot more time increments.

Your "weight mode" approach appears to be a force based load (via SFL,,)

Your "displace mode" approach is a direct displacement (DL,,,).  The displacement approach is inherently more stable than the force based approach.

If you post process your force vs displacment reaction for the converged solution, that might give you some helpful feedback as to how much force the structure can handle before failing with element distortion error.

Also, try lower order elements (PLANE182) with enhanced strain (KEYO,,1,2) for more robustness.