General Mechanical

General Mechanical

Backstress in usercreep.f subroutine

    • f_forndran
      Subscriber

      Hello,

      I am currently working on implementing an own developed creep model using the usercreep.f subroutine. In addition, the material in question is modeled with non-linear kinematic hardening according to the Chaboche model. This plastic model uses a backstress tensor the calculate the translation of the yield surface and now I would like to know if I could access this backstress tensor inside the routine.

      The routine is already using the following function to get the stress tensor

      call get_ElmData ('SIG', elemId,kDInPt, ncompgt, sig).

      Is there a similar possibility for the components of the backstress?

      Any help is much appreciated!

      Kind regards

      Freerik

    • David Weed
      Ansys Employee

      Hello Freerik,

      You may consider storing the back stress in a state variable. That way, you are not constrained by what the subroutines may/may not offer.

      Alternatively, see the ElemGetMat routine. It has variable storage for back stress: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v222/en/ans_prog/Hlp_P_UPFNEWEL.html

      This subroutine is technically for a user-defined element, but it may work for pre-existing elements.

    • f_forndran
      Subscriber

      Hello David,

      thank you very much for your reply and your suggestions. I decided to calculate the backstress within the usercreep routine and store it and not to implement the ElemGetMat routine. 

      Kind regards

      Freerik 

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