Anti-Zener model ($G^{\ast }(\omega )=i\omega {\eta }_s+Gi\omega \tau /(1+i\omega \tau )$)

A Maxwell fluid branch connected in parallel with a Newtonian dashpot. Branches share strain and their stresses add. With $\tau ={\eta }_M/G$, the displayed modulus uses the $e^{i\omega t}$ convention. Its low-frequency viscosity is ${\eta }_M+{\eta }_s$ and static shear modulus zero, so the material ultimately flows.