The path to fracture in granular flows: dynamics of contact networks

TL;DR

This paper investigates the fracture dynamics in granular flows by analyzing contact networks, revealing the formation of a giant component during shear and comparing experimental data with a strain-based link breakage model.

Contribution

It introduces a novel contact network approach to study fracture in granular flows and compares experimental results with a new strain-dependent link breakage model.

Findings

Giant component forms in contact networks under shear

Model qualitatively matches the onset of network percolation

Experimental networks are more clustered than model predictions

Abstract

Capturing the dynamics of granular flows at intermediate length scales can often be difficult. We propose studying the dynamics of contact networks as a new tool to study fracture at intermediate scales. Using experimental three-dimensional flow fields with particle-scale resolution, we calculate the time evolving broken-links network and find that a giant component of this network is formed as shear is applied to this system. We implement a model of link breakages where the probability of a link breaking is proportional to the average rate of longitudinal strain (elongation) in the direction of the edge and find that the model demonstrates qualitative agreement with the data when studying the onset of the giant component. We note, however, that the broken-links network formed in the model is less clustered than our experimental observations, indicating that the model reflects less localized breakage events and does not fully capture the dynamics of the granular flow.