BC of compression test in shape memory alloys
I am trying to simulate the compression test of shape memory alloys composite. At first, I want to simulate only single crystal in order to check whether my model is correct or not. I am using UMAT and abaqus for simulation. To check the results of simulation easily, I decided to use the single element with symmetric boundary condition (xy, yz, xz) on the cubic and apply displacement on the upper face. The stress components (S11,S22,S33) result is equal. So, it cancel each other which leads my simulation does not reach twinning condition, only elastic deformation. Any idea or suggestion about the boundary condition? or model?
Thanks in advance.