# Exploring the Regimes of Particle Behavior upon Impact via the Discrete Element Method

## TL;DR

This paper uses simulations to study how particles behave when they hit surfaces, identifying five distinct regimes based on impact conditions.

## Contribution

The study introduces five new regimes of particle behavior upon impact and links force transmission patterns to these regimes.

## Key findings

- Five behavioral regimes—rebounding, vibration, fragmentation, pancaking, and shattering—are identified based on impact conditions.
- In the fragmentation regime, rebound velocity decreases with increasing fragment size, except for the smallest fragments.
- Pancaking regime breakage does not follow traditional mechanistic models.

## Abstract

Discrete element method simulations are conducted to probe the various regimes of post-impact behavior of particles with solid surfaces. The impacting particles are described as spherical agglomerates consisting of smaller constituent (or primary) particles held together via surface adhesion. Under the influence of a wide range of impact velocities and particle surface energies, five distinct behavioral regimes—rebounding, vibration, fragmentation, pancaking, and shattering—are identified, and force transmission patterns are linked to post-impact behavior. In the rebounding regime, the coefficient of restitution decreases linearly as impact velocity increases and the particle agglomerate experiences compaction. In the fragmentation regime, rebound velocity generally decreases with increasing fragment size. The rebound velocity of fragments decreases with time except for the smallest fragments, which can increase in velocity due to collisions with other fragments of high velocity. Particle breakage in the pancaking regime does not follow common mechanistic models of breakage.