[APDL] hyperelastic material: convergence error

[saeed.akbari]

Hello everyone,

I'm trying to model a rubber-like material using neo Hookean hyperelastic material model:

ET,1,PLANE183 ! keyopt3=0 (plane stress)
KEYOPT,1,3,0
E=0.956e6
Nu=0.35
G=E/2/(1+nu)
K=E/3/(1-2*nu)
d=2/K
TB,HYPER,1,1,,NEO
TBDATA,1,G,d

But then I get this error message:

"One or more elements have become highly distorted. Excessive
distortion of elements is usually a symptom indicating the need for
corrective action elsewhere. Try incrementing the load more slowly
(increase the number of substeps or decrease the time step size). You
may need to improve your mesh to obtain elements with better aspect
ratios. Also consider the behavior of materials, contact pairs,
and/or constraint equations. If this message appears in the first
iteration of first substep, be sure to perform element shape checking."

I tried to change number of substeps or material properties, but it didn't work.
I appreciate any advice you might have.
_________________
Saeed Akbari, PhD student.
University of Toronto

[gaurav.nanajkar]

Hello Saeed,

Try using midside node dropped option in meshing.
It sometimes helps for hyperelastic material.

Best Regards,
Gaurav Nanajkar
Mechanical Analysis Engineer

Intelligent Energy,
Loughborough, UK