Fingerprinting Soft Materials: A Framework for Characterizing Nonlinear Viscoelasticity

TL;DR

This paper presents a new framework for characterizing nonlinear viscoelasticity in soft materials using large amplitude oscillatory shear, providing clearer physical insights and resolving ambiguities in traditional measures.

Contribution

It introduces a comprehensive scheme to quantify viscous and elastic nonlinearities simultaneously with improved interpretability and novel measures for nonlinear viscoelastic behavior.

Findings

Provides a physical interpretation of Fourier coefficients in nonlinear stress response.

Defines new measures that clarify nonlinear viscoelastic behavior.

Addresses ambiguities in traditional nonlinear viscoelastic moduli.

Abstract

We introduce a comprehensive scheme to physically quantify both viscous and elastic rheological nonlinearities simultaneously, using an imposed large amplitude oscillatory shear (LAOS) strain. The new framework naturally lends a physical interpretation to commonly reported Fourier coefficients of the nonlinear stress response. Additionally, we address the ambiguities inherent in the standard definitions of viscoelastic moduli when extended into the nonlinear regime, and define new measures which reveal behavior that is obscured by conventional techniques.