Maxwell fluid dynamic modulus ($G^{\ast }(\omega )=Gi\omega \tau /(1+i\omega \tau )$)

A series spring of modulus $G$ and dashpot of viscosity $\eta$ have $\tau =\eta /G$ and $\dot{\gamma }=\dot{\sigma }/G+\sigma /\eta$. With $e^{i\omega t}$ amplitudes, $G^{\prime }=G(\omega \tau {)}^2/[1+(\omega \tau {)}^2]$ and $G^{\prime \prime }=G\omega \tau /[1+(\omega \tau {)}^2]$. Low frequencies are fluid-like; high frequencies retain an elastic plateau. The loss peaks at $\omega \tau =1$.