Hello,
I am writing a user material subroutine for ANSYS, it incorporates the crystal plasticity equations for Magnesium's Basal slip systems. The equations are modelled using the resolved shear stress relations and the flow rules available in literature. The code works well in the Elastic region, but but everytime the RSS increases past the CRSS, the stresses become insanely large, like 10^17 and then code becomes unconvergent. I know the flow law of CPFEM is such that the rate sensitivity exponent may cause this to happen, but what should I do to fix it? I have written it only for Magnesium's Basal slip system, hence the hardening for that is linear dCRSS = (increment of shear strain in the slip system times*hardening modulus).
P.S I noticed that Dr. Huang's CPFEM code has an iteration subroutine, which iterates for the stresses and shear strain rates in the code, but I am not using this technique, is this something that must be done to achieve convergence?
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