theysy
commented
5 hours ago The effective stress of HAH consists of (1) Fluctuating component and (2) Stable component. The fluctuating component is to distort the yield surface based on the strain-path change indicator (cos X). The stable component corresponds to the effective stress of a yield function.
To get the derivative of HAH model, you would better to take this as a composite function: G(f(x)) So, the basic algebra will be dG/dx = (dG/df)*(df/dx) If f(x) is an yield function, then df/dx would be the derivative of yield function.
This derivation is not as complicated as you think.
Good luck!
Hello respected teacher, I am a graduate student from Yanshan University in China. You can call me Xiao Wang. I am very grateful that you have been answering my questions. I wonder if you still remember. I am very interested in your constitutive model for anisotropic hardening and have been studying it. I am confused about the derivative of the yield function that I sent to you in the attachment. I have a basic understanding of tensors, but I don't understand the tensor operations here. Please help me with this. I also emailed the author of this article, but have not heard back. Please help me, I really need your help. Thank you.