Fluctuations of global energy release and crackling in nominally brittle heterogeneous fracture

TL;DR

This study investigates the burst-like, crackling dynamics of energy release and crack speed in heterogeneous fracture, revealing scale-free fluctuations and proposing a material-constant fracture energy, with comparisons to theoretical models.

Contribution

It provides the first detailed analysis of crackling dynamics in heterogeneous fracture, linking energy release to crack speed and comparing observations with depinning interface models.

Findings

Energy release is proportional to global crack speed.

Fluctuations follow a power-law distribution, indicating crackling behavior.

Qualitative agreement with depinning models, with some discrepancies discussed.

Abstract

The temporal evolution of mechanical energy and spatially-averaged crack speed are both monitored in slowly fracturing artificial rocks. Both signals display an irregular burst-like dynamics, with power-law distributed fluctuations spanning a broad range of scales. Yet, the elastic power released at each time step is proportional to the global velocity all along the process, which enables defining a material-constant fracture energy. We characterize the intermittent dynamics by computing the burst statistics. This latter displays the scale-free features signature of crackling dynamics, in qualitative but not quantitative agreement with the depinning interface models derived for fracture problems. The possible sources of discrepancies are pointed out and discussed.