For the Fortran program that I build for my fatigue problem, I need to modify the compliance matrix C at each iteration. For that I have on one hand a subroutine UMAT which models the mechanical behavior of the material with the matrix C (implementation of DDSDDE) and on the other hand a subroutine USDFLD which calculates at each iteration the damage D. According to the value of D, the matrix C can change and that at each iteration. For this I have to call the matrix C (or DDSDDE) in the subroutine USDFLD, however DDSDDE is a variable defined only in the subroutine UMAT. How can two subroutines communicate with each other?
Anyone, please help me with that?
Hi!
The most common solution is to pass the value of D in the state variables array because the state variables can be accessed both by the UMAT and USDFLD.
Camille Le Goff Why do you need to use the USDFLD subroutine? You can access the stiffness and change it in damaged material in UMAT. You can find some examples of how to change the stiffness in damaged material in the following link:
https://caeassistant.com/product/advanced-umat-subroutine/#1619759693425-dfc77f70-3fba
https://caeassistant.com/product/advanced-umat-subroutine/#1576699949444-ba2c70af-8f69f314-3e84
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