VUMAT

Dear all,

I would like to ask you for advice. I am about to simulate a pull-through test (see attached picture) of a cladding panel made of a material with highly viscoelastic behaviour. I have parameters for Maxwell model (Prony series) obtained from test. I expect large deformation and probably cone failure (or tearing of the cladding panel). Therefore I would like to use Abaqus/Explicit. The problem is that I cannot use *visco step together with Explicit. Is there any way to solve it?

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:

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.

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,

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...

subroutine vumat(

c Read only -

Dear all,

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    

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

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?

      So far I follow the manual to assign the initial value via input file with material properties command as below (the line started with "*Initial Conditions" is line 361):

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

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. 

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

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.

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).