Hi everyone, i am trying to write umat subroutine for multi yield surface plasticity model.if its possible give me some information to do my project better and if some body has a similar umat i will be grateful to share it. thanks a lot.

  1. David Mašín
    David Mašín 6 years ago

    Dear Kamal, there is umat of sanisand (rotational hardening yield surface + bounding surface) at SoilModels which you can use to learn the procedure of umat setup. Also, you can download hypoplasticity umat, to see how to run explicit Runge-Kutta integration with substep control (this is also in SANISAND version). The rest is up to you, I think. Once you finish your project, do not forget to share it at SoilModels! Regards David

  2. Kamal Paknejad Author
    Kamal Paknejad 6 years ago

    thanks a lot dear Mr David for your comment. absolutely it will be my pleasure to share it.

  3. Frank Richter
    Frank Richter 6 years ago



    Multilinear kinematic hardening for cyclic plasticity
    Subroutine is accessible

    largely theoretical, without subroutine codes:

    Computational inelasticity / J.C. Simo, T.J.R. Hughes.
    Interdisciplinary applied mathematics; 7
    ISBN 0-387-97520-9
    Chapter 5: Nonsmooth Multisurface Plasticity and Viscoplasticity

    Publication in German:
    Schmidt, J., Kaliske, M. (2006)
    Zur dreidimensionalen Materialmodellierung von Fichtenholz mittels eines Mehrflächen-Plastizitätsmodells
    Three-dimensional material modelling of spruce wood using a multi-surface-plasticity model
    Holz als Roh- und Werkstoff 64:393–402.

    J.P. Bardet and W. Choucair
    A benchmark algorithm for elastoplasticity with multiple yield surfaces
    Soil Dynamics and Earthquake Engineering, 1991, Volume 10, Number 7, October, pages 341-347


    Subscribe to and seek assistance from the
    ABAQUS mailing list
    Search the archive of the list before posting in it.
    The list does not accept attachments.

    or from the ResearchGate discussion forum.

    For advice on mechanics in general, including modeling,
    you can consult

    As an introduction get the file
    http://imechanica.org/files/Writing User Subroutines with ABAQUS.pdf

    Simulia Learning Community

    Good luck


    • Dimitrios Konstantinidis

      Hello Frank,

      Thanks a lot for your answer. It is very helpful and descriptive.

      However, I haven’t managed to find the subroutine you are referring to from http://imechanica.org/node/18733 .

      Could you please help me with that?

      Also, your comment was in 2018. Do you think there are more sources of Multi-Surface models now? I am specifically interested in implementing the Prevost sand version and if possible using a simple explicit integration scheme like ‘Forward Euler’. Do you have any suggestions regarding that ?

      Looking forward to your response.

      Best regards,

  4. Frank Richter
    Frank Richter 2 years ago

    Hello Dimitrios

    “Subroutine is accessible” is misplaced there, sorry. In fact, the material models described on
    are wired into ABAQUS. They are not subroutines. Use them with parameters and you are done, much like using ELASTIC with two parameters.

    For some obscure reason they are not documented in the manuals. At least this was so when I last dealt with ABAQUS.
    Study my text on

    You “only” have to dig for the models.
    I advise you to ask around in FEM forums, or contact an ABAQUS representative.

    Another option: search online for the term “ABQ_SUPER_ELASTIC”. These are the intial characters prescribed for the material name in the built-in shape memory alloy. From a pdf for this model:

    “Note that the NAME parameter on *MATERIAL must start with ABQ_SUPER_ELASTIC_N1D (for beam elements), ABQ_SUPER_ELASTIC_N2D (for plane stress, shell or membrane elements), or ABQ_SUPER_ELASTIC_N3D (for 3D, plane strain or axisymmetric solid elements).”

    So, pick the initial part of this string. You get hits in your online search, also to publications in journals. Ask the authors, hopefully they can uncover the model for you or have a more intimate tie to ABAQUS than you might have.

    I have no access to ABAQUS any longer and cannot advise you on the sand model.

    Good luck,

  5. Dimitrios Konstantinidis

    Dear Frank,

    Thanks a lot for your immediate response and help.

    Also thank you for all the information regarding ABAQUS. However, I am mostly interested in scripts or algorithms to see how this type of models (multi-surface) are usually implemented – numerically integrated.

    The most helpful paper i have found so far is the one you were suggesting above:
    J.P. Bardet and W. Choucair
    A benchmark algorithm for elastoplasticity with multiple yield surfaces
    Soil Dynamics and Earthquake Engineering, 1991, Volume 10, Number 7, October, pages 341-347

    Therefore, I will probably start by implementing this algorithm in Matlab and see how it works.

    Had you found this publication for your own work, and if yes do you also implement constitutive models?

    Looking forward to your response.

    Again thanks a lot for your time.

    Best regards,

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