Sean Harvey
Ansys Employee

Hello Sarvesh,

Each step has a time associated. For example a model with 2 steps, step 1 can have a time of 1.0 sec and step 2 can have a time of 1.0 sec and the total time of the simulation will be 2.0.  But for static analyses, time is only a marker. It has no physical significance. So let's ignore time, and just stick with substeps. Since you have just 1 load, run it in one step.  At end of simulation you get to 1.0, model is has all the load applied.

Max substeps of 200 may not be enough. When the convergence is difficult, it can need more.  Set to 1000 or 2000.

Start with coarse mesh and avoid face sizing.  We want the best-shaped elements, not a detailed mesh. Later we can refine.

Uniform elements means not having large elements then very tiny ones.  You may not be able to get hex, but you can try hex dominate, or multizone too.  Tets can be fine as well. The key is they are not ill shaped, or become ill shaped, so element quality in large deformation hyperelastic is critical.

Drop the midside nodes (use linear elements, not higher order) for this hyperleastic.  Ansys will change the element formulation when you do this.  This will allow the element to be more robust in deformation and less likely to become ill shaped.  Don't drop midside notes when using test and non-hyperleastic materials (like stress analysis with linear materials such as metallics, plastics, etc.)  They will be too stiff.

By material stability, take a block and try to deform it in some standard modes of deformation. Tension, compression, shear.  Put boundary conditions so the block is uniformly loaded.  It is like a single element test of the material.  If you can't get larger strains that you expect from the material curve fitting with simple geometry, then the material calibration (curve fitting) may be the problem.  We want to isolate if it is material related or mesh related.  My prior comments above assume that material is not the problem (meaning the curve fits produce stable material response and behaviors).

Try all this before going to NLAD.  I may have some more tips to share later.  Thank you.