Propagating mode-I fracture in amorphous materials using the continuous random network (CRN) model

TL;DR

This study uses atomistic simulations with the CRN model to investigate mode-I fracture in amorphous materials, successfully reproducing experimental features including steady-state cracks, micro-branching, macro-branching, and crack velocity oscillations.

Contribution

It introduces a novel atomistic simulation approach for amorphous materials that captures steady-state fracture and branching phenomena.

Findings

Achieved steady-state crack propagation in amorphous materials.

Observed micro- and macro-branching increasing with driving force.

Explained crack velocity oscillations consistent with experiments.

Abstract

We study propagating mode-I fracture in two dimensional amorphous materials using atomistic simulations. We used the continuous random network (CRN) model of an amorphous material, creating samples using a two dimensional analogue of the WWW (Wooten, Winer & Weaire) Monte-Carlo algorithm. For modeling fracture, molecular-dynamics simulations were run on the resulting samples. The results of our simulations reproduce the main experimental features. In addition to achieving a steady-state crack under a constant driving displacement (which had not yet been achieved by other atomistic models for amorphous materials), the runs show micro-branching, which increases with driving, transitioning to macro-branching for the largest drivings. Beside the qualitative visual similarity of the simulated cracks to experiment, the simulation also succeeds in explaining the experimentally observed oscillations of the crack velocity.