Kramers–Kronig relations for nonlinear rheology. Part II: Validation of medium amplitude oscillatory shear (MAOS) measurements

The frequency dependence of third-harmonic medium amplitude oscillatory shear (MAOS) modulus $G_{33}^{*}(\omega)$ provides insight into material behavior and microstructure in the asymptotically nonlinear regime. Motivated by difficulty measurement MAOS moduli, we propose a test for data validation based on Kramers-Kronig relations. We extend approach used to assess consistency linear viscoelastic expressing real imaginary parts as combination Maxwell elements: functional form kernels is inspired time-strain separability (TSS). statistical fitting technique called SMEL test, which works well broad range materials models including those that do not obey TSS. It successfully copes with experimental are noisy, or confined limited range. When modes obtained from predict first-harmonic $G_{31}^{*}$, it possible identify timescales over exhibits