Crack initiation in viscoelastic materials

TL;DR

This paper investigates the microscopic mechanisms behind crack initiation in viscoelastic materials, highlighting how nonlinear bond dynamics lead to crack formation, differing from traditional solid fracture models.

Contribution

It introduces a new microscopic model for crack initiation in viscoelastic materials based on nonlinear bond dynamics, supported by analytical and numerical verification.

Findings

Critical crack length depends on bond kinetics and applied stress

Derived analytical equations describe crack emergence

Numerical verification confirms the model's predictions

Abstract

In viscoelastic materials, individually short-lived bonds collectively result in a mechanical resistance which is long-lived but finite, as ultimately cracks appear. Here we provide a microscopic mechanism by which cracks emerge from the nonlinear local bond dynamics. This mechanism is different from crack initiation in solids, which is governed by a competition between elastic and adhesion energy. We provide and numerically verify analytical equations for the dependence of the critical crack length on the bond kinetics and applied stress.