Stress Softening in UMAT

[NazBaba]

Hi all,

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

Stress decreases during phase transformation in our model but I can't do this in UMAT. When stress is needed to decrease, abaqus job stops and there is no change in the command window. I wonder that is there anything which I can do when stress starts to decrease in UMAT? It can be in input file or subroutine file.

Thank you.
Nazım Babacan

 

[abqMaster]

That means your UMAT is not properly writen. Strain softening is not the direct cause. Check your jacobian.