Im pretty new to implementation of Umats but i have coded some materials for a 3D case using solid elements, which have worked out fine. Now Im trying to do the same thing using shell elements (S4 and S4R) and I have some questionmarks here...
- What are the compeonets in the stress/stain tensor (STRESS and DSTRAIN) (S11,S22,S12,S33 ???) ?
- What is the size of the Jacobian?
- Do I need to convert my 3D implementaion to plane stress?, and if that is needed do I have to provide the out of plane strain (how is that done in this case)?
I would be very thankfull for some valuable hints 🙂