Hi all,

I am
implementing the constitutive behavior of CuAlNi shape memory alloy during
uniaxial loading using UMAT. My new question is that:

When phase
transformation first starts, umat finds jacobian using my numeric finite
difference method for jacobian. But in same step, stresses and strains cannot
be obtained and then umat uses smaller and different strains and changes
jacobian values. After one step calculation abaqus job finishes with unexpected
error. What could be the problem? What can I do?

Thank you.

Nazım Babacan