Nonlinear Force Propagation during Granular Impact

Abstract

We experimentally study nonlinear force propagation into granular material during impact from an intruder, and we explain our observations in terms of the nonlinear grain-scale force relation. Using high-speed video and photoelastic particles, we determine the speed and spatial structure of the force response just after impact. We show that these quantities depend on a dimensionless parameter, $M^{\prime }=t_c{v}_0/d$, where $v_0$ is the intruder speed at impact, $d$ is the particle diameter, and $t_c$ is the collision time for a pair of grains impacting at relative speed $v_0$. The experiments access a large range of $M^{\prime }$ by using particles of three different materials. When $M^{\prime }\ll 1$, force propagation is chain-like with a speed, $v_f$, satisfying $v_f\propto d/t_c$. For larger $M^{\prime }$, the force response becomes spatially dense and the force propagation speed departs from $v_f\propto d/t_c$, corresponding to collective stiffening of a strongly compressed packing of grains.

3 figures, 5 pages

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Cited by in corpus (4)

• Granular Response to Impact: Topology of the Force Networks
• Vertical dynamics of a horizontally-oscillating active object in a 2D granular medium
• Force and Mass Dynamics in Non-Newtonian Suspensions
• Granular Impact: A Grain-scale Approach