Influence of particle sphericity on granular dampers operating in the bouncing bed motional phase

This paper presents new research to determine the effect of particle shape on the energy dissipation in a granular damper operating in the bouncing bed motional phase. This is accomplished by conducting controlled experiments and validated Discrete Element Method (DEM) simulations for a broad collection of spheroidal particle shapes at vibration amplitudes of up to 50 g. The findings show that non-spherical particles significantly change the condition known as the “bouncing bed onset amplitude” which is the vibration amplitude at which granular damping is maximised. It is shown that the packing parameter known as the coordination number is an indicator of this change and that there is a correlation between the shear properties of the granular medium and the amplitude at which it delivers optimum energy dissipation. This paper also presents a sensitivity analysis specific to the bouncing bed phase which considers variations in particle modulus, density, restitution coefficient and friction. This shows that the observations about the effects of particle shape are valid over a broad range of conditions.