Reply To: Ansys usercreep subroutine

[Sasi Kumar Tippabhotla]

Hi John, thank you for your response. My question is not about how the usercreep subroutine works. I understabd that it is based on strain hardening model of primary creep. May be my question in the original post is unclear. Let me elaborate.

I am trying to understand the implicit formulation of the creep function here. To be specific, I am trying to understand the calculation logic used for "delcr". If it is an implicit formulation (I guess it is),

delcr = e_cr(n+1) - e_cr(n) = C1*(sigma(n+1)^C2)*(e_cr(n+1)^C3)*exp(-C4/T(n+1))*delta_t

where n indicates the current time step and delta_t = t(n+1)-t(n). I expect the formulation integrates the creep function to eliminate the (n+1) terms and solve for the delcr. That is why there is a long "if-else" logic to address different scenarios. I am not able to understand how the eauations used for "delcr" calculations are arrived at. Explanation of the same is not available in the theory manual or user programmer's guide