Observation of the Kibble-Zurek Mechanism in Microscopic Acoustic Cracking Noises

TL;DR

This study demonstrates the Kibble-Zurek mechanism in microscopic acoustic crack noises, linking nonlinear elastic zone dynamics to crack propagation and weakening, providing new insights into crackling phenomena.

Contribution

It provides the first direct mapping of nonlinear elastic zones to acoustic noise phases and confirms the Kibble-Zurek mechanism in crack dynamics.

Findings

Nonlinear zone size follows a power-law dependence on traversal rate.

Acoustic noise phases reflect the formation of a weak zone near crack tips.

Kibble-Zurek mechanism explains the critical dynamics of crack propagation.

Abstract

The fast evolution of microstructure is key to understanding crackling phenomena. It has been proposed that formation of a nonlinear zone around a moving crack tip controls the crack tip velocity. Progress in understanding the physics of this critical zone has been limited due to the lack of hard data describing the detailed complex physical processes that occur within. For the first time, we show that the signature of the non-linear elastic zone around a microscopic dynamic crack maps directly to generic phases of acoustic noises, supporting the formation of a strongly weak zone near the moving crack tips. We additionally show that the rate of traversing to non-linear zone controls the rate of weakening, i.e. speed of global rupture propagation. We measure the power-law dependence of nonlinear zone size on the traversing rate, and show that our observations are in agreement with the Kibble-Zurek mechanism (KZM) .