title: Revealing the structure of a granular medium through ballistic sound propagation.
abstract: We study the propagation of sound through a bidimensional granular medium consisting of photoelastic disks, which are packed into different crystalline and disordered structures. Acoustic sensors placed at the boundaries of the system capture the acoustic signal produced by a local and well-controlled mechanical excitation. By compressing the system, we find that the speed of the ballistic part of the acoustic wave behaves as a power law of the applied force with both exponent and prefactor sensitive to the internal geometry of the contact network. This information, which we are able to link to the force-deformation relation of single grains under different contact geometries, provides enough information to reveal the structure of the granular medium.
authors.affiliation: Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne, France.
authors.forename: S
authors.initials: S
authors.lastname: Lherminier
authors.affiliation: Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne, France.
authors.forename: R
authors.initials: R
authors.lastname: Planet
authors.affiliation: Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne, France.
authors.forename: G
authors.initials: G
authors.lastname: Simon
authors.affiliation: Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne, France.
authors.forename: L
authors.initials: L
authors.lastname: Vanel
authors.affiliation: Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne, France.
authors.forename: O
authors.initials: O
authors.lastname: Ramos