Cracking Piles of Brittle Grains

TL;DR

This paper introduces a stochastic model for crack propagation in granular piles, revealing how grain brittleness and packing randomness influence crack morphology, avalanche size distribution, and force fluctuations.

Contribution

It presents a novel numerical model that captures crack avalanches in granular piles, highlighting the effects of grain ductility and packing randomness on cracking behavior.

Findings

Cracked areas show diverse morphologies depending on grain properties.

The external force remains constant over a wide range of cracked fractions.

Avalanche size distribution follows a power law with exponent approximately 2.4.

Abstract

A model which accounts for cracking avalanches in piles of grains subject to external load is introduced and numerically simulated. The stress is stochastically transferred from higher layers to lower ones. Cracked areas exhibit various morphologies, depending on the degree of randomness in the packing and on the ductility of the grains. The external force necessary to continue the cracking process is constant in wide range of values of the fraction of already cracked grains. If the grains are very brittle, the force fluctuations become periodic in early stages of cracking. Distribution of cracking avalanches obeys a power law with exponent $\tau = 2.4 \pm 0.1$.