ABAQUS UMAT

I am using Dr. Huang's crystal plasticity code for an adiabatic process where temperature increase due to deformation need to be calculated. Dr. Huang's CP UMAT code does not consider the temperature effect of shear rate or hardening. Is there a way to include temperature effects in the current UMAT code?

http://www.columbia.edu/~jk2079/Kysar_Research_Laboratory/Single_Crystal...

The implicit implementation of creep in abaqus requires dh/d(\delta \epsilon_c ) as Jacobian in Newton-Raphson's iteration. The derivative can be expanded as shown in the figure attached. The term dh/dq, the one underlined by a green stroke, is expected to be provided by users through specifying DECRA, whereas the term dq/d(\delta \epsilon), underlined by a red one, is confusing me. It seems that that term is computed by Abaqus but I have no idea how it is done. The same question applies to the last derivative on the right hand side.

Hello everyone, 

I found that there is no comprehensive topic about how to calculate material jacobian matrix for UMAT while it's one of the most complicated and important parts of writing a subroutine and a lot of the researchers deal with it. 

I think it would be great if experts share their sources and experiences here for all. I personally, try to provide the basics and essential materials as well. 

Here is an essential available PDF on Imechanica:

Hello all,I am simulating epoxy damage using a non-local damage model through abaqus user subroutine UMAT.Based on the idea of Prof. Bazant's non-local treatment, the non-local damage at a particular integration point is obtained by averaging the local damage values of all the integration points within a characteristic length (Lc) of that point.

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Hi!

I am just a beginner in Abaqus UMAT and I have started working with Dr Huang's crystal plasticity UMAT in Abaqus.

When I am assigning one material constants for one element crystal it works but when I try to assign it to more than one element for one crystal (for example group of elements with same grain orientation) it give me error code 144.

Can anybody explain me the reason?

Thanks in advance,

Kind regards,

Omid

Dear All,
I am okay in ABAQUS although trying subroutines for the first time.
I am trying to modify some codes available online, but the primary UMAT which I am posting here, is not working.
It shows no error in .log file but the job monitor says "Problem during compilation - D:\Abaqus Work Directory\Trial_user_subroutine\try\Umat_mine.for"

Please help me this, its very urgent.
Thanking you all,
P.S. The code is attached in .txt format
Here is the code

Dear all,

In this study, we presented a numerically robust procedure to evaluate 4th order tangent moduli which are vital for acheiving quadratic convergence of global Newton-Raphson scheme.

In this study, the proposed method is verified for hyperelastic models alone. However, the same can be extended to other constitutive models.

The paper can be found at

Numerically approximated Cauchy integral (NACI) for implementation of constitutive models

10.1016/j.finel.2014.05.016

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