Construction of motional phase maps for granular dampers

Abstract

Harmonically vibrated granular media exhibit a variety of motional behaviours depending on amplitude, frequency, and vibration-to-gravity directional orientation. Motional behaviour defines the physical interactions of particles in the granular media and therefore the energy dissipation performance. A "phase map" that describes motional behaviour over broad ranges of frequency and amplitude is therefore a very useful tool in damper design. However, at present, identification of the operating motional conditions within the granular media has only been conducted by visual observation of the particles following a particle-level simulation or a specifically designed experiment. Because of this, design optimisation over a broad range of amplitude and frequency becomes costly. This paper aims to help reduce this cost through the development of approximate phase maps based on expected dissipative interactions of particles. Three-dimensional discrete element method simulations are conducted over a wide range of excitation intensities under two different vibration-to-gravity directional orientations (i.e., perpendicular, and parallel to the standard gravity direction) to allow the observation of as many motional phases as possible. The effect of particle size, volume filling ratio and particle shape on granular energy dissipation sources are also investigated.