Discrete element method simulations and experimental study of interactions in 3D granular bedding during low-velocity impact

Abstract

The impact of a spherical intruder on a bedding of spherical particles and the behaviour of particles during the splashing phenomenon were studied experimentally and via discrete element method (DEM) simulations. The objective of this study was to gain deeper insight into the physical mechanisms governing the behaviour of the particle bedding during low-velocity impact. The experiments were performed using a high-speed camera to capture the splash of the particles. A piezoelectric ceramic pressure sensor located at the bottom of the container was employed to measure the pressure impulse generated by the intruder impact. We obtained good agreement between the DEM simulations and experimental results for all the considered parameters of the impact process. The study allowed a better understanding of the interactions in a granular bedding during impact at micro-scale. The results indicated that the dynamics of the intruder-particles, particle-particle, and particles-bottom interactions were similar, having a nonlinear increase that accompanied an increase in the impact velocity. This was caused by a local increase in the effective stiffness of the bedding resulting from simultaneous multi-collisions. The coefficient of particle-particle friction significantly affected all the measures considered: speed of the compression wave, amplitude of the impact force, amount of kinetic energy transferred from the intruder to the particles, depth of penetration and crater diameter, and number of ejected particles and their kinetic energy.