<POTENTIAL> z6_gen_evp#
This potential gives hardening variable evolution in terms of the
un-coupled internal state variables and not as a function of the
associated forces. The criterion still includes the coupled terms, of
course. This type of interaction was given in versions 6 and below. In
the case of no interaction this potential is identical to the
gen_evp potential.
Example#
\[\ten X_{X1} = \frac{2}{3}C_{X1}\ten \alpha_{X1} + \frac{2}{3}C_{int}\ten \alpha_{X2}\]
\[\ten X_{X2} = \frac{2}{3}C_{X2}\ten \alpha_{X2} + \frac{2}{3}C_{int}\ten \alpha_{X1}\]
but the evolution of the internal variables has no coupling. The evolution equation for a nonlinear kinematic hardening variable is changed to:
\[{\ten m}_{kin} = {\ten n} - D\ten \alpha\]