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Writing User Subroutines with ABAQUS

Ahmad Rafsanjani's picture

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


Example 1: UMAT for Isotropic Isothermal Elasticity

Example 2: UMAT for Non-Isothermal Elasticity

Example 3: UMAT for Neo-Hookean Hyperelasticity

Example 4: UMAT for Kinematic Hardening Plasticity

Example 5: UMAT for Isotropic Hardening Plasticity

• VUMAT Interface


Example 6: VUMAT for Kinematic Hardening
Example 7: VUMAT for Isotropic Hardening


Thank you very much.

attash3099's picture


Min Yi's picture

thanks a lot```````````

thanks a lot



thanks a lot for your file.

I wanted to model the behaviour of a poylmere reinforced with fibers. the first step is to model the matrix alone, which has a hyperelastic isotropic behaviour. 

 Do you know if the formula 

δ ( Jσ ) = JC : δD


δD = sym ( δF ⋅ F – 1 ) 

can be apply in case of finite hyperelasticity? If it is the case, how can you express the Jacobian matrix C, when the stress is a function of the left-green tensor 


for example: σ = a1. I + a2. B +a3.B:B?

thanks a lot,

hi Mr Rafsanjani,

this is romik khachatourian from SUT (master student, Structure), im beginner in abaqus, i need to write a UMAT code for Plastically Graded Material, do you have any experience in graded material?

please call me on

thank you so much bro


jason Zhu's picture

 Thanks a  lot


Jason Zhu Best Regards

Hi all,

 there is a text error on slide 44. The isochoric component of Neo-Hookean law is dependent to the modified invariants. That means I1 is the first invariant of the modified left Cauchy Green tensor, B*=J^(-2/3)B.

But the code is correctly write ^_^ 



Thank u.











Ahmad Rafsanjani's picture

Now you can find the complete document in attachment.

nasri's picture

Hello I'm about to implement behavior in  abaqus  of the sheet metal anisotropic. for beginners .i work on the implimentation oh Hill48 that al ready exists  on a fite VUMAT abaqus;but  i encountred several problems I'll be very grateful if your send me a sample file Vumat HILL48 or Barlat,pending your repose ,please accept the assurances of my distinguished salutations sincerly

's picture

Thanks al lot to ahmadpeik for shaqring the two valuable tutorials


I am master student. I am modelling bullet impact into woven composite using Abaqus.

I have to use VUMAT subroutine to define failure criteria. Can u give some example or website that i can browse to solve my problem?

I am using 2D plane stress (classical laminate theory).


Vinicius Aguiar de Souza's picture

Thank you so much for the valuable material.

parvizs's picture

Thanks alot...         


i have a problem with jacobian matrix in umat

im trying to model a micro plan behavior of concrete and i havnet any explicit relation between stress and strain but i have a suroutin that gives strain and passes stress

and i havnet any rate of stress or strain to calculate jacobian

can you help me?!!! 

Is it possible to know who has written this document? I have a very specific question about Neo-Hookean model implementation given in this document which I have been asking for long time and it seems that nobody either knows or is willing to answer the question. Hence I would like to contact the author of this document and get it clarified. Or a contact person in Abaqus would just do fine. Please let me know if possible.



Gayan Aravinda's picture

Hi I am new to imechanica. could you please let me know how can i download that document please?
i could not see the attachement here. Thank you  very much.

mattia.bacca's picture

Dear Ahmad, Thank you for your usefull guide to the beautifull world of UMAT. I have a question for you about the example 5 (Isotropic Hardening): The hardening curve seem to be importd externally from a variable called TABLE, how do you build that TABLE and how do you connect it with the UMAT subroutine? Thank you in advance.Best Regards,Mattia

Is any similar UMAT for linear and non-linear viscoelastic materials available? Please upload.

Hamed-yaghoubi's picture

Thanks a lot, I was wondering if you give me more information about linking abaqus 6-13-1 and Fortran 90 in Windows 8. I have big problem with this.  My abaqus shows the error "user subroutine only in .for or .obj format", I wrote subroutine in .f90 format and cannot compilie

Thans a lot!

ciprian.zub's picture

Dear Ahmad Rafsanjani,

Could u recommand me some references/tutorials/examples/code for UMAT/VUMAT for combined iso-kin hardening to model metal plasticity with yield plateau (chaboche for kin hard (mulltiple backstresses), multilinear for iso hard?

Thank you very much!

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