Double Power Model

The double power law is available in the form

{\dot{\bar{ε}}}^{c r} = A_{1} \exp (- \frac{B_{1}}{(θ - θ^{Z})}) {(\frac{\tilde{q}}{σ_{0}})}^{C_{1}} + A_{2} \exp (- \frac{B_{2}}{(θ - θ^{Z})}) {(\frac{\tilde{q}}{σ_{0}})}^{C_{2}},

where

${\dot{\bar{ε}}}^{c r}$: is the uniaxial equivalent creep strain rate, $\sqrt{\frac{2}{3} {\dot{ε}}^{c r} : {\dot{ε}}^{c r}},$
$\tilde{q}$: is the uniaxial equivalent deviatoric stress,
$θ$: is the temperature,
$θ^{Z}$: is the user-defined value of absolute zero on the temperature scale used,
$σ_{0}$: is the normalized stress, and
$A_{1}$ , $A_{2}$ , $B_{1}$ , $B_{2}$ , $C_{1}$ , and $C_{2}$: are other material parameters.