I am trying to reproduce a TX monotonic, compressive test on a sand by using a 1-element, axisymmetric ABAQUS FE model, assigned to a SANISAND material. For this purpose, I am using a umat subroutine that is made available at soilmodels.com

In the ABAQUS model, I have set a material with 36 “depvar” state variables and 19 “user material – mechanical” parameters, as suggested by the documentation of the package. The only additional feature I set to the material is the density, set = 1 (ton/m^3). The adopted element type is axisymmetric stress, hybrid formulation (CAX4H). Two steps of analysis are set, static general. A confinement load of 100 (kPa) is applied to the two boundaries of the soil element throughout a “confinement” and a “shear” static steps of analysis. During the “shear” step, I applied a vertical (axial) displacement of the upper boundary of the sample, producing a deviatoric stress.
I properly linked the subroutine to the job in the “General” option of the job menu.
When I run the job, an error occurs before the analysis is run reporting “Abaqus/Standard Analysis exited with an error – Please see the message file for possible error messages if the file exists.”

What could the problem be? Thanks to anyone who could help in troubleshooting.

  1. Srinivas Vivek Bokkisa

    Hello Ricardo,
    I face the same issue. Did you find a solution?

  2. Srinivas Vivek Bokkisa

    Hello Riccardo,
    I face the same issue. Did you find a solution?

    MOHD SAQIB 2 years ago

    There are a few suggestions!.
    1- Check the Msg file or Dat file to find the error.
    2-Please, check all the constants (i.e-19) in your case are properly calibrated with units. If you aren`t incorporating all parameters, reduce constants.
    3- Check your drainage conditions, Put value of bulk_w according to the drainage conditions.

  4. Srinivas Vivek Bokkisa

    Dear MOHD SAQIB,

    Thank you for the suggestions.

    Can you guide me how to initialize the state variables?
    The manual says, “state variables should all be initialised to 0 using sdvini.f”. But I don’t see a “sdvini.f” file in the downloaded package.
    I tried adding SDVINI subroutine of abaqus to the UMAT code but that didn’t help. I am unsure if it is the right thing do. Any help is much appreciated.

    Thank you

    MOHD SAQIB 2 years ago

    SDVINI is a must. If it is not in UMAT, then you have to include it and initialize it according to your requirements.

  6. Srinivas Vivek Bokkisa

    Thank you MOHD SAQIB for your insights.

    Commenting out all the “stop” commands in the umat code solved my issue.

    • Sanchari Mondal
      Sanchari Mondal 2 years ago

      Hi Srinivas,

      Did you use all the 19 parameters? I am trying to run a drained TXC 3D model, but I face convergence issue.

    • Riccardo Zabatta
      Riccardo Zabatta 2 years ago

      Hi Srinivas,

      thanks to your suggestion, I was able to run the Subroutine. Thank you so much! Hope this can be useful for other users.

  7. Safia EDAOUDI
    Safia EDAOUDI 1 year ago

    Hello, my subroutine works fine, it runs on abaqus but gives weird results for tx monotonic test, I think it has to do with parameter 18 “ptmult”. How did you configurate it?
    Thanks in advance.

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