Probing Weak Forces in Granular Media through Nonlinear Dynamic dilatancy: Clapping Contacts and Polarization Anisotropy

Vincent Tournat (1) , Vladimir Zaitsev (2) , Vitali Goussev (1) , Veniamin Nazarov (2) , Philippe Béquin (1) , Bernard Castagnede (1)

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans
2 Institute of Applied Physics of RAS

Rectification (demodulation) of high-frequency shear acoustic bursts is applied to probe the distribution of contact forces in 3D granular media. Symmetry principles allow for rectification of the shear waves only with their conversion into longitudinal mode. The rectification is due to nonlinear dynamic dilatancy, which is found to follow a quadratic or Hertzian power law in the shear wave amplitude. Evidence is given that a significant portion of weak contact forces is localized below 1e-2 of the mean force — a range previously inaccessible by experiment. Strong anisotropy of nonlinearity for shear waves with different polarization is observed.

Mots clés: Nonlinear acoustics; granular elasticity; self-demodulation; distribution of contacts

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]; Matière Molle [cond-mat.soft]

Vincent Tournat, Vladimir Zaitsev, Vitali Goussev, Veniamin Nazarov, Philippe Béquin, et al.. Probing Weak Forces in Granular Media through Nonlinear Dynamic dilatancy: Clapping Contacts and Polarization Anisotropy. Physical Review Letters, 2004, 92 (8), pp.085502. ⟨10.1103/PhysRevLett.92.085502⟩. ⟨hal-00171056⟩