Dear all, I am a PhD student in Hohai University. Recently I have been trying to simulate a triaxial compression test using the hypoplasticity model for clay. The UMAT subroutine is provided by Pro Masin on this website (umat_hcea.for). Figure 1 shows the parameters that I set in the model based on the link ‘’, but there is no result or error in the calculation, as shown in Figure 2. Could you please tell me what is the possible reason for this problem?

20200926223556-1.png 20200926224830-2.png 20200926223529-0.png

  1. Arie Koot
    Arie Koot 4 years ago

    it does not look like a warning of hp_umat.
    it’s probably from another abaqus material

    • Tao Zhu Author
      Tao Zhu 4 years ago

      yeah, I set another material in this model that led to this warning which disappeared after deleting this material .

  2. Lukas Reindl
    Lukas Reindl 4 years ago

    Hi Tao Zhu, try to define 20 material-parameters instead of 29 (for PLAXIS) and 16 state-variables (depvar). I already have used this model with Abaqus. The model was running perfectly.

    • Tao Zhu Author
      Tao Zhu 4 years ago

      Thanks for your advice. I have defined 20 material-parameters instead of 29, but it doesn’t work and the error is ‘User subroutine umat is missing’. There should be no problem with the path of the user subroutine file. Could you please tell me what is the possible reason for this problem?

      I read the umat subroutine ‘umat_hcea.for’ and I think the number of the material-parameters should be 22—alpha_power=parms(21),avoid=props(22).

    • Tao Zhu Author
      Tao Zhu 4 years ago

      However the sand model with ‘umat.for’ can run perfectly… I’m really confused that the clay model aborted with the error ‘User subroutine umat is missing’ but the sand model can run successfully.

  3. Hans Henning Stutz
    Hans Henning Stutz 4 years ago

    Dear Tao,

    I guess the issue is simply to solve. Open the umat_hcea.for with your favorite text/code editor and change the name from ” subroutine umat_hcea(…” to ” subroutine umat(…”.

    best regards,

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