Convergence issue - traction of hyperelastic ring

[Lmarais]

Hi all,

I am trying to model with ABAQUS a ring traction test with a cylindrical rigid hook pulling on a hyperelastic ring.
There is perfect contact between the hook and the ring (frictionless and hard contact).

I am using the Holzapfel hyperelastic law with kappa parameter = 1/3 and D=0, so it is isotropic and incompressible.
For some material parameters combinations I can obtain convergence but for some combinations it will stop at 50 or 60% of the step. In the message file I get a "FORCE EQUILIBRIUM NOT ACHIEVED WITHIN TOLERANCE" error.

I tried to change the mesh and the increment size, without success. When I change the geometry of the ring it works but I want it with this specific size.
I am running the simulation with displacement control until the radius of the ring is increased by 50%.

Does anybody know where the problem comes from ?
Any ideas or suggestions?

I've attached my input file.
Thank you very much for helping.

 

[DrBwts]

Try using the explicit solver, it is a lot more stable for large deformations.

 

[rstupplebeen]

Here is a running list of things that I have checked:
1. Properties Module>Material>Evaluate Your material model errored so I substituted a simple NeoHooke model for the remainder.
2. Changed incrementation to Automatic from Fixed. This allows the step size to reduce if needed.
3. Changed to second order elements (likely not needed but tried anyway)

Unfortunately none of these changes helped appreciably but thought that it might be helpful.

Personally I have never modeled this large of deformation with Plane Stress elements. Next I would try modeling with solid elements with a single element through the depth.

I hope this helps.

Thank you.

Rob Stupplebeen
OptimalDevice.com
My Personal WP