Extended Chaboche viscoplastic model for cyclic loading

These days I've been applying oneself to implement the Chaboche viscoplastic model in ABAQUS user-subroutine for simulating the cyclic loading in single crystals.
The procedure can easily get out. I'm not sure about the problem, the deduction of Jacobian, the convergence? 
Btw, I know there is free subroutine for crystal plasticity by Huang YG. I wonder if the UMAT routine for chaboche model is available, then I can generalize it to fit for my case.
If pity there isn't, guide or example for viscoplastic model can be of great help also.
Thanks a lot


I am doing similar thing

I am doing similar thing with you, coding a UMAT in abaqus for a
elastic-viscoplastic model. I work in a civil engineering field and this model
is overstress viscoplastic  type of model for soil. With experience of
implementing the elastic-viscoplastic model in AFENA, I still feel difficulty in
convergence issues.
Hope we can share some experience in this work.

I have a technical report of

I have a technical report of implement viscoplastic model for single crystle. let me know if you want

UMAT chaboche elasto-plastic model for cyclic loading subroutine


i am a student of civil engineering of Padova, Italy. I'm writing my
thesis about a fatigue cracks in railway bridges. I need to implement a
UMAT subroutine  for a Chaboche elasto-plastic model for cyclic
loadings into my ABAQUS model. Can anyone help me or post me the

 my mail is bojan.huljev@yahoo.it

thank you very much