Hi all,

I am implementing the constitutive behaviour of two-crystal CuAlNi shape memory alloy during uniaxial loading using UMAT. My aim is to pass single crystal to polycrystal model. So, I am trying two-crystal problem firstly. I have no trouble with implementing single crystal and I get results of volume fraction and stress. However, in two-crystal problem, the solution doesn't converge. I use only elastic region and there is no plastic region in my problem. I transform only elastic matrices and transformation strains local to global in two-crystal program. (I calculate the consistent Jacobian by using the finite difference method.)





Thank you.
Nazım Babacan