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arXiv · 0803.3955

Evidence of Raleigh-Hertz surface waves and shear stiffness anomaly in granular media

L. Bonneau·B. Andreotti·E. Clement
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Abstract

Due to the non-linearity of Hertzian contacts, the speed of sound in granular matter increases with pressure. Under gravity, the non-linear elastic description predicts that acoustic propagation is only possible through surface modes, called Rayleigh-Hertz modes and guided by the index gradient. Here we directly evidence these modes in a controlled laboratory experiment and use them to probe the elastic properties of a granular packing under vanishing confining pressure. The shape and the dispersion relation of both transverse and sagittal modes are compared to the prediction of non-linear elasticity that includes finite size effects. This allows to test the existence of a shear stiffness anomaly close to the jamming transition.

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L. Bonneau, B. Andreotti, E. Clement. 2008-03-27. Evidence of Raleigh-Hertz surface waves and shear stiffness anomaly in granular media. https://doi.org/10.1103/physrevlett.101.118001

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