Finite strain plasticity in principal space UMAT ABAQUS HELP

[ryellava]

Hello all,

I am trying to write an UMAT for finite strain plasticity in principal space (Algorithms for static and dynamic multiplicative plasticity that preserve the classical return mapping schemes of the infinitesimal theory -1992-Simo).

I am having convergence issues in abaqus. I verified my consistent algorithmic tangent modulus but could not find any problem with it. I am also attaching the expression of the spatial tangent modulus. It is obtained by pull back operations on the material tangent stiffness modulus.

I am little confused about the tangent modulus that I have to provide for the DDSDDE in abaqus. Do I need to change/modify the spatial tangent modulus (attached) to get compatability with ABAQUS.

Any help is greatly appreciated.

-Ravi

 

[EnergyMix]

Not everyone in this forum uses Abaqus. Since you haven't received any answers after a week, it's probably best to post your question over in forum799.

Want to know the do's and don'ts of Eng-Tips? Read FAQ731-376.
English not your native language? Looking for some help in getting your question across to others or understanding their answers? Go to forum1529.