Forming and breaking of contacts in jammed granular media by nonlinear acoustic waves

Abstract

We investigate the nonlinear response of pulsed sound transmission in weakly compressed granular materials, composed of glass beads and sand. Amplitude and velocity of longitudinal waves are simultaneously measured. We observe that weakly compressed packings can both exhibit strengthening and weakening of the sound velocity and transmission amplitude when excited by high amplitude sound. These effects are due to the changes of the contacts between the particles and although the effective medium theory qualitatively describes these effects it fails to quantitatively account for them. © 2013 AIP Publishing LLC.