Series spring and Voigt-branch creep
= Series spring and Voigt-branch creep
{title2=$J(t)=1/E_0+(1/E_1)(1-e^{-E_1t/\eta})$}
A <spring> $E_0$ in series with a parallel spring-dashpot branch $E_1,\eta$ has creep compliance $J(t)=1/E_0+(1/E_1)(1-e^{-E_1t/\eta})$. It includes immediate and delayed recoverable <strain>, but no unbounded viscous flow. Large <strain>, damage or <anisotropy> require additional constitutive structure.