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VUMAT

Karol Frydrych's picture

Polycrystal plasticity in Abaqus/Explicit

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Hello everyone!

My goal is to model large plastic deformations of polycrystalline metals using crystal plasticity and ALE adaptive meshing. In order to do that I want to use VUMAT subroutine in Abaqus/Explicit, since as far as I understand Abaqus/Standard is not good for large deformations and it doesn't support ALE adaptive meshing for that purpose.

New publication for UMAT and VUMAT in ABAQUS

We performed a comprehensive study of a large class of Implicit and Explicit integration algorithms for Elastic-Plastic behaviors in Finite Element Analysis (FEA) developed in UMAT and VUMAT for ABAQUS and presented various unique results. We also showed detailed integration algorithms for both Associated and Non-Associated Flow Rules with mixed isotropic and kimenatic hardening with expandable number of internal variables (damage and etc).

Full bibliographic details:

bitamendi's picture

Looking for a VUMAT programmer to share publication with

Dear researchers,

 

I’m Joseba Mendiguren, researcher at the Advanced Manufacturing Group of Mondragon Unibertsitatea. I’m currently working on advanced yielding/hardening models for metals.
I’m in the middle of a paper writing work but I cannot find time to sit down and program the VMAT that I need to run some simulations for the paper. I’m looking for a VUMAT programmer researcher willing to work on the topic and share the publication authorship on return.

VUMAT general queries

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Hi,

I am beginner in abaqus and I want to write a VUMAT for VIB method to simulate fracture, while writing VUMAT i encountered following problems 

1) For 2D plane stress problem how to calculate strainInc(*,3). It is increment for that step or value of strain till that step?

2) What is effect of that defination on answer I am getting?

Gayan Aravinda's picture

VUMAT of Drucker Prager, help needed please..

Hi Everyone,

                    I have written Drucker Prager in VUMAT version as shown below..but still there are some deviation with the original in built version of ABAQUS. I have all the notes how i derived these equation.could you please show me where the code has gone wrong or have i missed a critical point in here..i tried my best to spot the error but could not..may be you all experts could find it. Thank you very much. 

 

subroutine vumat(

c Read only -

     1  nblock, ndir, nshr, nstatev, nfieldv, nprops, lanneal,

Gayan Aravinda's picture

vumat for isotropic perfect plastic

Hi all,

        I wrote VUMAT subroutine using fortran 77 for perfect plasticity unisng von mises plasticity..when analysed it using unidirectional tensile simulation for a simple cube model...it seems to me that it only goes through elastic deformation and not plastic...i tried to find out what is the error..but could not find it..could anyone please find what is the error in this code..i have attached the VUMAT code for the reference...thank you very much...

 

Use Vumat to simulate the hot ductile fracture criterion of Freudenthal

Dear everybody,
I have just studied Abaqus and would like to use Vumat to simulate the hot ductile

fracture criterion of Freudenthal which have the equation: D=integral(0-fracture strain)

of (Smises stress)*d(strain). The fracture will be appear when I reach 1 unit.
Could you please show me how to write algorithm adding temperature to calculate (D) and

out put (D) in Vumat.

thanks you so much

I am looking forward to hearing from you

hongfengtl    

Manaliac's picture

VUMAT user subroutine dealing with several integration points

Hello All,

 

I have some questions concerning the VUMAT subroutine, I run successfully an
analysis on one element with one integration point,
so my first question is how to code for several integration points (
nblock concerns only the material points not the integration points)?

My second question is how to write for datas dependent of temperature (like Young and shear modulus)??

Thank you all for your answers.

Manal

How to Assign Initial Solution-dependent State Variable to VUMAT

Hi everyone,

      I just constructed a VUMAT which including 3 state dependent variables ( nstatev =3 ), let say these three state dependent variables each have a initial value of 10, 20 and 30, may I know how to assign these initial values into the simulation or VUMAT?

Defining density as a solution dependent variable in VUMAT (Abaqus/Explicit)?

Hi All,

I am trying to simulate tooth deformation. It involves that the density of tooth changes with deformation. I want to know is it possible to define density as a solution dependent variable in VUMAT?

 Thank you in advance!

 Shunlai

bitamendi's picture

Mixed hardening Amstrong-Frederick and Ludwik J2 plasticity model VUMAT implementation

Hi, I’m trying to implement a mixed hardening J2 plasticity model. The idea is to use the Ludwik law to represent the isotropic hardening and the Amstrong-Frederick law for the kinematic hardening, both combine in a J2 classic von Mises model.

 

I need some advice for the return mapping algorithm.

 

Setting Simple Compression Test In VUMAT

Hi, i am trying to test a bulk metallc glass VUMAT with a simple compression test simulation. But since VUMAT is a Abaqus Explicit subroutine, that means I must set my compression simulation with setting of Abaqus Explicit right? So far I only have the experience in conducting compression test simualtion using ABAQUS Standard setting like static general step and surface-to-surface contact (standard). I don't know how to set up a simple compression test simulation with Abaqus Explicit settings, can anyone help me please?

Thanks and regards.

Siple Compression Test With Abaqus Explicit

Hi, i am trying to test a bulk metallc glass VUMAT with a simple compression test simulation. But since VUMAT is a Abaqus Explicit subroutine, that means I must set my compression simulation with setting of Abaqus Explicit right? So far I only have the experience in conducting compression test simualtion using ABAQUS Standard setting like static general step and surface-to-surface contact (standard). I don't know how to set up a simple compression test simulation with Abaqus Explicit settings, can anyone help me please?

Thanks and regards. 

ABAQUS user material subroutine VUMAT and Eulerian mesh...

Hi there,

 Has anyone ever used a vumat subroutine with Eulerian elements? it seems that the stress update formulation is different from the way it is in Lagrangian approach! If you have any experience in this regard I'd highly appreciate if you share it with me.

 thanks

Plasticity Data in Vumat

Hello everyone,

  I am using a VUMAT with isotropic hardening in my three dimensional model. Can someone tell me how is plasticity data passed into this subroutine? In VUMAT for kinematic hardening we define the yield stress and hardening modulus along with E and poisson's ratio in *User Material. I did not find any isotropic hardening VUMAT examples in manual. Do we define the hardening modulus or the yield stress-plastic strain data in isotropic hardening VUMAT? I will be really thankful if anyone can help me.

 

Thank you

Swapnil

how can I link vumat to cohesive elemet

hi,

    recently,i want to write a delamination law using vumat,but coh3d8 element with  a traction-separation has s33,s13,s23.in vumat,stressold(nblock,ndir+nshr),i don't kown if s33 is  correspond to stressold(nblock,3),and if s23 is  correspond to stressold(nblock,5),

   i hope someone can help me.

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

A Postdoctoral Position (£30,594-£32,458 pa) Available in Computational Mechanics in Liverpool UK

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.

Iterations in VUMAT

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

 

VUMAT for Nitinol --- why VUMAT and not UMAT?

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.

Abaqus/Explicit VUMAT works fine on 32 bits Abaqus - Fails on 64 bits Abaqus with more than 1 processor!!!

Hi,
Here is the issue:
I am working with a x64 version of
Abaqus/Explicit (6.8-2), and a 32bits version (6.7-1). MS VS2005 is
installed with the x64 compiler tools, Intel Fortran is correctly
installed (IA-32 and Intel64 versions). My OS is Windows Vista Enterprise (64 bits).
The routine is compiled and linked correctly by lauching the appropriate ifortvars.bat file prior to executing abaqus.


Everything works perfectly with the 32 bits version of Abaqus+Compiler, with one or more processors (I have 8 of them).

VUMAT and ALE in ABAQUS

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

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.   

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