General Mechanical

General Mechanical

retrieve plastic strain as output

    • myu25
      Subscriber

      hi guys,

      I am working the plastic model via umat through ANSYS. there is one external subroutine I have used which is called (get_ElmData). I am trying to retrieve the plastic strain as output and then for the inverse analysis; for ANSYS-based, they are storing plastic strain with the label ('EPPL'), but for user-defined, since ANSYS has no idea what user has stored, so it must have another Label. Question here is: what would be the Label, and how do I define it inside the external subroutine that I mentioned above.

    • David Weed
      Ansys Employee

      Hello, thank you for your question submission. When using get_elmData with usermat, ‘EPPL’ is a valid label for retrieving the plastic strain; you can use kchar = ‘EPPL’. See the documentation for get_elmData in the MAPDL Programmer’s Reference here: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v222/en/ans_prog/accessingsolutionmatdata.html.

      Alternatively, get_elmData can also retrieve the plastic strain values using state variables, or kchar = ‘SVAR’. In usermat, the first seven state variables are reserved for plastic strain output:

      c    ustatev   (dp,ar(nstatev),io)      user state variable
      c            ustatev(1)                     – equivalent plastic strain
      c            ustatev(2) – statev(1+ncomp)   – plastic strain vector
      c            ustatev(nStatev)               – von-Mises stress

      • myu25
        Subscriber

        Very Appreciate your reply, For the EPPL, did you mean I will write the kchar = 'EPPL' before the "call" or others?

        I was writing them like this

        .

        since the 16th to 21st state variables are defined as plastic strain, so I try to write this statement to let ansys know, the output that I want is statev(16:21)

        For your link, I wouldn't able to open it. If you don't mind, could we change the place for further discussion? My email address is myu25@uiowa.edu

    • David Weed
      Ansys Employee

      Hi myu25, regarding your first question about EPPL, the way you have it in get_ElmData is correct. 'kchar' is the first entry in the subroutine. If you can't access the online help, I believe that you should have internal help documentation that came with your ANSYS install. Alternatively, you can 'SVAR' for kchar. ncomp is the number of components for your stress/strain quantity. FYI, I'm not authorized to contact you outside of this forum.

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