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Stress Softening in UMAT

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NazBaba

Mechanical
Joined
May 2, 2011
Messages
9
Location
TR
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
 
That means your UMAT is not properly writen. Strain softening is not the direct cause. Check your jacobian.
 
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