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How to use previous values of calculation as the initial conditions in UMAT subroutine ABAQUS

How to use previous values of calculation as the initial conditions in UMAT subroutine ABAQUS

How to use previous values of calculation as the initial conditions in UMAT subroutine ABAQUS

(OP)
Hi guys,
I am trying to implement an UMAT subroutine into ABAQUS.

It is a very simple non-linear elastic model, in which the Young's modulus depends on the mean pressure, in details, E=3*(1-2*poisson)*p/kap (where, p is mean pressure, poisson=0.3 is Poisson's coefficient and kap=0.005 is swelling index). The initial stress is 1e5 Pa for sigma11, 22 and 33.

When I run the subroutine , it gives linear behavior with E=3*(1-2*0.3)*(3*1e5/3)/0.05 (which is the Young's modulus calculated with the initial stress). If the initial stress is 0 for all components, it gives us 0 for all calculation because E=3*(1-2*0.3)*(3*0/3)/0.05=0. Obviously, these results are not correct

I would like to ask if you could help me to solve this problem (define the initial conditions as the previous values for each variables).

Thanks in advance

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