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Need help for running UMAT of Dr. Huang's single crystal

Soud Choudhury's picture

Hello Everyone,

I am a new member of imechanica. I have started to learn UMAT of Abaqus to model my material behavior ( Cu6Sn5, HCP) using crystal plasticity finite element model. I found Dr. Huang's single crystal UMAT to start learning UMAT and I thought that it would be a great guide to start though it is written for FCC mat. But unfortunately I was not able to run the UMAT with it's input file.

It is showing error " Too many attempts were made for this increment". I have no idea where I went wrong as I just ran the UMAT with it's own physical model. Please can anyone provide me a running UMAT of Dr. Huang ? I think there is something I need to change. Also, guideline for learning UMAT will be a great help.


I have used the following code and devided into .inp file and .for file.

Also , I am using Abaqus 6-12-1. Please help me on this issue. 

Please mail me at


Thank you so much. 


Frank Richter's picture

You cannot start learning UMAT with a code of this complexity.

Get the file User Subroutines with ABAQUS.pdf
it may show up as

 The error message is not specific to UMAT.


Soud Choudhury's picture

Soud Farhan Choudhury

J.Tu's picture

i also a fresher of UMAT, and i use Dr. Huang's code to learn it, but it is difficult to understand.

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