Importance of non-affine viscoelastic response in disordered fibre networks

TL;DR

This paper introduces a numerical method to predict the viscoelastic response of disordered fibre networks, highlighting the significance of non-affine deformations and mode delocalization in their mechanical behavior.

Contribution

A novel numerical approach to quantify non-affine viscoelastic spectra in disordered fibre networks, applicable across various types of fibre materials.

Findings

Shear modulus increases with frequency as non-affine modes are suppressed.

Low frequency modes are dominated by fibril bending and are delocalised.

Method reveals the critical role of non-affinity in peptide gel mechanics.

Abstract

Disordered fibre networks are ubiquitous in nature and have a wide range of industrial applications as novel biomaterials. Predicting their viscoelastic response is straightforward for affine deformations that are uniform over all length scales, but when affinity fails, as has been observed experimentally, modelling becomes challenging. Here we introduce a numerical methodology to predict the steady-state viscoelastic spectra and degree of affinity for disordered fibre networks driven at arbitrary frequencies. Applying this method to a peptide gel model reveals a monotonic increase of the shear modulus as the soft, non-affine normal modes are successively suppressed as the driving frequency increases. In addition to being dominated by fibril bending, these low frequency network modes are also shown to be delocalised. The presented methodology provides insights into the importance of non-affinity in the viscoelastic response of peptide gels, and is easily extendible to all types of fibre networks.