Mechanisms in Impact Fragmentation

TL;DR

This study uses 3D Discrete Element simulations to analyze impact fragmentation of spheres, revealing detailed crack evolution, mechanisms, and how fragment sizes depend on impact velocity, aligning with experimental observations.

Contribution

It provides a detailed numerical analysis of fragmentation mechanisms and crack evolution in impact fracture, improving understanding of fragment size distribution and impact energy effects.

Findings

Meridional cracks initiate inside the specimen with quasi-periodic angular distribution.

Fragment mass distribution fits a Weibull distribution for large fragments.

Mean fragment sizes scale with impact velocity.

Abstract

The brittle fragmentation of spheres is studied numerically by a 3D Discrete Element Model. Large scale computer simulations are performed with models that consist of agglomerates of many spherical particles, interconnected by beam-truss elements. We focus on a detailed description of the fragmentation process and study several fragmentation mechanisms involved. The evolution of meridional cracks is studied in detail. These cracks are found to initiate in the inside of the specimen with quasi-periodic angular distribution and give a broad peak in the fragment mass distribution for large fragments that can be fitted by a two-parameter Weibull distribution. The results prove to be independent of the degree of disorder in the model, but mean fragment sizes scale with velocity. Our results reproduce many experimental observations of fragment shapes, impact energy dependence or mass distribution, and significantly improve the understanding of the fragmentation process for impact fracture since we have full access to the failure conditions and evolution.