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Abaqus UMATs

I have funding for software development to provide a UMAT interface in the parallel versions of the code from Smith I.M. and Griffiths D.V. "Programming the Finite Element Method", 4th Edition, Wiley, 2004.

I would be interested to hear about any open source UMATs available for download. I'd also like to hear from anyone who might like to use their closed source UMATs in a parallel environment.

The funding has been awarded by the UK National HPC Service HECToR to encourage the greater use of HECToR for Structural Engineering.

Abaqus, UMAT, Constitutive law, Powder

Dear all,

 

I have several questions about how to use existing constitutive law of material to code UMAT in Abaqus. I have carried out experiment for several powder materials, including metal, ceramic, polymer powders. The powder aggregate is compacted in a cylindrical die. After the compaction, relationships between axial stress and axial strain, radial stress and axial strain are obtained. The material under such condition is always treated as elastic plastic material.

I am getting an error while running Single crystal UMAT of Huang

Hi

***ERROR: THE SOLUTION-DEPENDENT STATE VARIABLE INDEX MUST BE AN INTEGER",

this is a error which pops out when i try to run Huang's single crystal UMAT. Do anybody have experienced the same kind of error

 

Karthic 

 

Ahmad Rafsanjani's picture

Writing User Subroutines with ABAQUS

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

Sharing an abaqus UMAT using an elastic viscoplastic model for soil

Here is a UMAT using an  elastic viscoplastic model for soil

Modifed Cam-clay model coupled with viscosity.

 

ABAQUS - UMAT (Free Download for Research Purposes)


A user-defined subroutine in ABAQUS for viscous soils.

Introduction:

The ABAQUS subroutine is for viscous soils, which
usually have the following characteristics.

A question on UMAT implementation of non-local theory

 

Hi, friends,

Now, I am implementing the non-local continuum theory in ABAQUS through UMAT programming.

Unfortunately, I have been obstacled by the following question:

On one hand, in non-local continuum theory, the non-local strain of every particular integration point is determined by the global strain field all over the specimen.

How to program the change of Young's modulus depending on the former element

Hello,

Now I want to simulate the change Young's modulus due to the mechanical stimulus in soft tissue. In our soft tissue(scaffold) we have seeded living cells and these cells produce the collagen fiber type-II which could be interpreted as change of Young's modulus. The Young's modulus of neighbour elements of the cells have to change depending on the Young's modulus of former elements like domino.

I have two constitutitve equations programmed in UMAT i. e. for scaffold and for fibers and they run good.

Shape memory alloy material models including plasticity implemented in ABAQUS

I am working with shape memory alloys (nitinol), and am in that respect investigating fracture behaviour of NiTi, using, among other things, simulations in ABAQUS. ABAQUS doesn't have a material model that include plasticity unless you pay for it. I am wondering if anyone have implemented either of the following models as a UMAT, and if you are willing to share the code with me.


The models I am interested in are:

How to Compute MATERIAL JACOBIAN?

Free Tags: 

Hi All,

 Thanks for your help so far. I have one last question to the forum. Please do answer whatever you know. How can I compute Material Jacobian for my UMAT subroutine? 

best regards

--dinesh

UMAT subroutine in ABAQUS for elasto-plastic cyclic loadings

I want to implement the elasto-plastic model for cyclic loadings (I suppose
something like chaboche) into the UMAT subroutine in my ABAQUS  model ,
but I haven't enough knowldge for do this. I read some book like mechanichs of solid materials but i don't understand how to implement my constitutive law into the subroutine. until the load is static i don't have many problems, but when i work with cyclic load I'm non able to generate a cyclic increments of plastic behaviou.

UMAT: Calling a another subroutine in UMAT, Errors during job execution

Hi,

I am in process of implementing the Bergstroem-Boyce Model. In a first
step I am just considering the hyperlastic part of it (Network A:
8-chain). I have implemented this part in a UMAT using a numerical
approach for the elasticity tensor (Forward Difference Approximation
with perturbation of F).

I have two problems:

1.
------------------------
In order to keep my UMAT as easy to read as possible I have tried to keep the FDA in a separate file using

call KFDA_Jaumann(dfgrd1,......)

Shunlai.Zang's picture

When and where the stress objective rates are used in ABAQUS software?

Hi everyone,

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

About the polycrystal plasticity

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

Extended Chaboche viscoplastic model for cyclic loading

Choose a channel featured in the header of iMechanica: 

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

Jintegral and Umat subroutine

Choose a channel featured in the header of iMechanica: 

Hello,

azadpoor's picture

Sharing ABAQUS UMAT and VUMAT subroutines

Choose a channel featured in the header of iMechanica: 

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

azadpoor's picture

Sharing ABAQUS UMAT and VUMAT 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

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