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Interface between UMAT (Abaqus/Standard) and VUMAT (Abaqus/Explicit).
Description: Interface between umat (Abaqus/Standard) and vumat (Abaqus/Explicit) user defined model standards. Note: the interface is tested with sand and clay hypoplastic umats. A simple switch should be changed in the umat code when used within vumat, search for a keyword "ABAQUS EXPLICIT" in the umat code. Description of the implementation and a user manual can be found in the following report.
Authors: Developed by Bienen et al. (2014)
References:
Associated Software and Constitutive Models
The Abaqus Unified FEA product suite offers powerful and complete solutions for both routine and sophisticated engineering problems covering a vast spectrum of industrial applications.
Dear …,
How could we include the library of UMAT (ABA_PARA.INC) to VUMAT (VABA_PARA.INC) ? I need to call the ROTSIG subroutine in UMAT but it could not work in VUMAT library.
It is highly appreciate if you could help me to solve this problem.
Best Regards.
Hello,
I read the research report and the FORTRAN code available at https://soilmodels.com/download/vumat_umatinterface-zip/. It sounds quite interesting but I have a couple of questions about the FORTRAN code:
1- Did you have specific reasons with determining the state variables of 2 and 7, when using the following lines in the FORTRAN code? What are those state variables? and Could you put other state variables in this section of your code?
!******
!for Abaqus data check prior to analysis
if (totalTime .eq. zero) then
do km = 1, nblock
stateNew(km,2) = zero
stateNew(km,7) = stateOld(km,7)
enddo
endif
!******
2- In the part of “assignment of further variables used by umat”, you mentioned that you are not quite sure about some lines. Have you ended up with another update version of this code so far?
Thank you for your time with these questions,
Greetings
i used interface Vumat with Umat for simulating CEL problem, after 50% of analysis, i got the error as “Excessive incremental rotation of the elements in element set ” i researched the meaning about this error in literature but h couldn’t find how fix it. please advise.
Regards
Hello sir,
I am interested in something very similar to this … Actually i am modelling the drilling of a steel auger in a soil to make a room for pile rafting… Could you please guide mw with this as CEL technique i am using with conventional abaqus Mohr coloumb/ Modified cam plasticity model is not predicit the accurate results
Dear Bienen
Good, Dr. can give me an example of a complete soil model using vumat for hypoplastic model.
Thank you very much, Dr. for example .inp and .for files.
mail: sg-thaihoangan@e-university.edu.vn
Best regards
Hoang An,
Dear Prof. Bienen,
I am really confused. When I call the vumat.for file based on the umat.for file through the VUMAT_UMATinterface in Abaqus/Explicit, which lines in Line 1~4 should be activated and which lines should be inactived?
Line-1 testing=0
c For use in PLAXIS, activate the following line
Line-2 if(kstep.eq.1 .AND. kinc.eq.1) testing=1
c For use in ABAQUS EXPLICIT, activate the following line
Line-3 if(kstep.eq.1 .AND. kinc.eq.1) testing=3
c For use in ABAQUS, the two lines above should be inactive
Line-4 if(norm_D.eq.0) testing=2
Dear Prof. Bienen,
At first, thanks for your interface conversion code which is very useful for user-defined material models, I tried hard for running this code for a simple known Umat model just like elasticity and faced such a warning
“A material defined in user subroutine VUMAT must be defined as purely elastic (using the initial elastic modulus) at the beginning of the analysis (stepTime=0)”
Which leads to an uncompleted analysis. I just confused and have some questions
Is this warning related to prior analysis? And how can I define state variables 1 and 7 ?, I guess it seems that the compiler does not recognize it.
Best regards