VUMAT

Dear All,

 I think that many students are looking for some tutorials about writing a UMAT in ABAQUS.

You can find a comprehensive tutorial for elastic problems.

This file contains: 

• Motivation

• Steps Required in Writing a UMAT or VUMAT

• UMAT Interface

• Examples

Example 1: UMAT for Isotropic Isothermal Elasticity

Example 2: UMAT for Non-Isothermal Elasticity

Example 3: UMAT for Neo-Hookean Hyperelasticity

Closing date for receipt of applications: 30 January 2010You will join a research project “Optimise blast resistance of novel composites made with fibre metal laminates (FMLs)” sponsored by the Leverhulme Trust. The project will be jointly supervised with Prof. Cantwell who is an expert on testing of novel composites. The project is to develop comprehensive finite element models capable of simulating various deformation and failure modes relating to composite features of FMLs subjected to extreme loading conditions.

Dear all,

I' m trying to make a model in VUMAT for shape memory alloy based on Lagoudas 's thermomechanical constitutive model. It seems that It's necessary an iteration to evaluate the thermoelastic prediction.

My questions are : is it possible to use an iterative loop in the VUMAT or it's better to avoid it??Could someone suggest me a different way so that I can avoid the iterative loop?

Many thanks,

Cece

Dear all,

 I'm new in imechanica. I need some informations about VUMAT for Nitinol. I would like to implement in fortran a subroutine for the behaviour of shape memory alloy.I looked for some subroutines already implemented but they have been developed in the implicit way.

It's true that with the VUMAT(explicit) I could have some problems of stability and convergence.Could someone suggest me any reason to make this model in the VUMAT?I know that in VUMAT I can't redifine the time increment so before running the analysis It's important to pay attention on Dt.

Hi all,

     Here I encoutered a error in ABAQUS when I include ALE with VUMAT. When ALE was not included with VUMAT, my job can work well while with the combination of VUMAT and ALE, the job cann't work any more due to a "Signal 8" error. And if I use a built-in material model and at the same time ALE, a job can work. Furthermore, element failure is considered in all of the cases.

    Anyone can give some suggetion? Thanks in advance!

Xinke

Hi everyone,

    I have a question about the objectivity tensor in ABAQUS software. Below is my question.