Complex viscosity
= Complex viscosity
{title2=$\eta^*(\omega)=\int_0^\infty G(s)e^{-i\omega s}ds$}
For the convention $e^{i\omega t}$, complex viscosity is the ratio of oscillatory <shear stress> amplitude to <shear rate> amplitude. A causal <relaxation modulus> gives the displayed transform. Its associated complex shear modulus is $G^*=i\omega\eta^*=G'+iG''$, where $G'$ is the <storage modulus> and $G''$ the <loss modulus>.