Darveaux Model

A standard hyperbolic sine law,

{\dot{\bar{ε}}}_{s}^{c r} = C_{s s} {[\sinh (α \tilde{q})]}^{n} \exp (- \frac{Q}{R (θ - θ^{Z})}),

describes the secondary creep (steady-state) component.

Modify the steady-state law to include the primary creep effects through

{\dot{\bar{ε}}}^{c r} = {\dot{\bar{ε}}}_{s}^{c r} [1 + ϵ_{T} B \exp (- B {\dot{\bar{ε}}}_{s}^{c r} t)],

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,
$R$: is the universal gas constant,
$θ$: is the temperature,
$θ^{Z}$: is the user-defined value of absolute zero on the temperature scale used,
$Q$: is the activation energy,
$C_{s s}$: is the steady-state creep prefactor,
$α$: is the steady-state creep power law breakdown, and
$n$ , $ϵ_{T}$ , and $B$: are other material parameters.