# The emergence of crack-like behavior of frictional rupture: Edge singularity and energy balance

## TL;DR

This paper demonstrates that frictional rupture can often be described by a crack-like fracture mechanics energy balance, explaining the emergence of crack-like behavior in frictional interfaces and highlighting deviations due to non-edge-localized dissipation.

## Contribution

It shows that under realistic conditions, frictional rupture dynamics are approximately governed by a fracture mechanics energy balance, bridging friction physics and crack theory.

## Key findings

- Frictional rupture often follows a crack-like energy balance.
- Deviations occur due to non-edge-localized dissipation.
- Stress drops are key to crack-like behavior emergence.

## Abstract

The failure of frictional interfaces -- the process of frictional rupture -- is widely assumed to feature crack-like properties, with far-reaching implications for various disciplines, ranging from engineering tribology to earthquake physics. An important condition for the emergence of a crack-like behavior is the existence of stress drops in frictional rupture, whose basic physical origin has been recently elucidated. Here we show that for generic and realistic frictional constitutive relations, and once the necessary conditions for the emergence of an effective crack-like behavior are met, frictional rupture dynamics are approximately described by a crack-like, fracture mechanics energy balance equation. This is achieved by independently calculating the intensity of the crack-like singularity along with its associated elastic energy flux into the rupture edge region, and the frictional dissipation in the edge region. We further show that while the fracture mechanics energy balance equation provides an approximate, yet quantitative, description of frictional rupture dynamics, interesting deviations from the ordinary crack-like framework -- associated with non-edge-localized dissipation -- exist. Together with the recent results about the emergence of stress drops in frictional rupture, this work offers a comprehensive and basic understanding of why, how and to what extent frictional rupture might be viewed as an ordinary fracture process. Various implications are discussed.