= Retardation time
{disambiguate=viscoelasticity}
{title2=$\tau_r$}
= Retardation time
{synonym}
The characteristic time for a delayed <strain> response to approach equilibrium under a step in <stress>. For a <Kelvin-Voigt model> with elastic modulus $E$ and viscosity $\eta$, the equation $\eta\dot\varepsilon+E\varepsilon=\sigma_0$ gives $\varepsilon=(\sigma_0/E)(1-e^{-t/\tau_r})$, where $\tau_r=\eta/E$. A <relaxation time> instead describes decay of <stress> after an imposed strain; the two times need not coincide in a <standard linear solid model>.
Back to article page
