Collisional Model of Energy Dissipation in 3D Granular Impact

TL;DR

This paper presents a collisional model explaining energy dissipation during 3D granular impacts, validated through experiments measuring forces on an impactor in dense granular media.

Contribution

It introduces a collisional-based model for impact stopping force and verifies it with high-speed imaging experiments, linking drag to intruder shape and grain density.

Findings

Impact force is due to sporadic grain collisions.

Intruder shape and grain density influence drag.

Model accurately predicts impact dynamics.

Abstract

We study the dynamic process occurring when a granular assembly is displaced by a solid impactor. The momentum transfer from the impactor to the target is shown to occur through sporadic, normal collisions of high force carrying grains at the intruder surface. We therefore describe the stopping force of the impact through a collisional based model. To verify the model in impact experiments, we determine the forces acting on an intruder decelerating through a dense granular medium using high-speed imaging of its trajectory. By varying the intruder shape and granular target, intruder-grain interactions are inferred from the consequent path. As a result, we connect the drag to the effect of intruder shape and grain density based on a proposed collisional model.