Non-linear material in Nastran

[Ale22pic]

Hi guys!
First of all, I'm new to this forum and this is my first thread, so if there are some mistakes in the way that I posted it tell me. Anyway, I'm working on finite element simulation with Patran and Nastran on a particular composite material, actually, we can say it's a sandwich. I'm trying to simulate the different behavior of these sandwich faces because they act differently in compression and tension. So I thought to write a field in which I set the strain and stress, but I can only use this field for isotropic/nonlinear elastic material but the material used for the faces is a composite made of unidirectional fibers layers at different angles. If I wasn't clear tell me and I'll give you more details in a way to resolve this problem together.
Thanks for your cooperation!

 

[SWComposites]

You use PCOMP/MAT8 cards for composite layer definition.

I dont recall, but there may be a way to define a nonlinear MAT8 card with different tension and compression moduli. Read the manual.

 

[Ale22pic]

Hi, SWComposites! Thanks for your answer. Honestly, I took a look at the manual but I didn't find anything useful, but probably I wasn't good in searching (I read Nastran 2018 Quick Reference Guide). Would you like to give me more details if you know more about this kind of problem?