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Converting Umat to Vumat

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  • Converting Umat to Vumat

    Dear All,

    I am working on Morph model(Method of rubber phenomenology), I have the model written in Umat and want to convert to Vumat, since I am beginner in writing subroutine, help will be appreciated. I have attached a Umat code in the mail, which is to be converted to Vumat.

    Thanking you,
    Harsha
    Attached Files

  • #2
    There are a few things to consider, beside the numerical effectiveness required by a material routine for implicit vs explicit time integration:

    1. You do not provide a tangent stiffness matrix (Jacobian) to the solver in a VUMAT.
    2. Stresses and state variables are fed into the VUMAT as blocks of a certain length. the UMAT considers one integration point at a time, while the VUMAT gets info about a bunch of them. You can loop over the collection of integration points in a VUMAT.
    3. Shear strain components are defined differently (13 and 23 components are reversed).

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    • #3
      Dear matsgd,
      Thank you for your help, now I solved problem

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      • #4
        Hi Harsha,
        I have a same problem, I want to convert UMAT to VUMAT, could you please tell how did you do it ?
        Thanks.

        Comment


        • #5
          Try
          https://soilmodels.com/umat-vumat/
          I do not know if this interface is mature.

          Regarding this interface, and your query in general:

          Subscribe to and seek assistance from the
          ABAQUS mailing list
          https://groups.yahoo.com/group/r
          or
          http://www.eng-tips.com/threadminder.cfm?pid=799
          or from the ResearchGate discussion forum.

          Search the archive of the list before posting in it.
          The list does not accept attachments.

          For an intro to subroutines get the file
          http://imechanica.org/files/Writing User Subroutines with ABAQUS.pdf

          Good luck

          Frank

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          • #6
            Thank you Frank,
            Can you please explain to me how to use this interface ? should I copy the UMAT subroutine into the interface VUMAT or what to do exactly ?
            I appreciate your feedback

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            • #7
              No idea, I never used it.
              Inquire on that site or in the mailing list

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