Hi

I’m trying to develop a VUMat routine so I’ve already
started to learn its features. I recently got this problem that what exactly
the variable stepTime means! I created a model with 3 steps including the initial
step and I coded my routine somehow that when the stepTime is equal to 0 it
prints something into a file. Surprisingly only once in whole analysis the
stepTime would be 0 and that’s exactly at the beginning of the analysis when
totalTime is in fact 0. Could anyone please explain why this happens?

Thanks

Hi everyone,

I am trying to build polycrystal plasticity model  by using UMAT subroutine in ABAQUS. As we know, the orientation of grain is always espressed by Euler's angles. What I want to know is  how to assign different initial orientations to different grains using Euler's angles in Umat subroutine. Could anybody tell me how to do? Is there any example ?

Many Thanks,

Yuanpei

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

maxianfeng@gmail.com

Hello,

I have noticed that a lot of people are using UMAT and VUMAT material model
subroutines for their researches. However, most of these subroutines do not
find their way to free code market and remain in the hands of the developers.
Therefore, a lot of wheel re-inventing has to be done by other people. Since
development and testing of a material subroutine takes a damn long time, I
think it is a good idea if each of us can share the subroutines she has
developed with the others. I know that a couple of subroutines are publicly
available and many other people also know that. Please comment about less-known
freely available subroutines.

I have noticed that a lot of people are using UMAT and VUMAT material model
subroutines for their researches. However, most of these subroutines do not
find their way to free code market and remain in the hands of the developers.
Therefore, a lot of wheel re-inventing has to be done by other people. Since
development and testing of a material subroutine takes a damn long time, I
think it is a good idea if each of us can share the subroutines she has
developed with the others. I know that a couple of subroutines are publicly
available and many other people also know that. Please comment about less-known
freely available subroutines.