Simple VUMAT qustions

[Fredrik]

I am a beginner in writing vumat and I would need some help in getting started. The model which I am going to implement is a simple linear elastic model for membrane elements (m3d3 and m3d4r) in explicit.

1. Which tensor should I get the elastic strains from, defgrad, strech or straininc?
2. Should I use plane stress state or a general state of stress?
3. If I want to add a state variable to the model, e.g. plastic strain or a damage variable, how can I write this to field data in the odb?

Best Regards,

Fredrik

[Jorgen]

1. I would user strainInc for a linear elastic material.
2. I would use plane stress for membrane elements
3. You can output statevariables using the SDV variable in the Output Field command

- Jorgen