title: Reorganization of a dense granular assembly: the unjamming response function.
abstract: We investigate the mechanical properties of a static dense granular assembly in response to a local forcing. To this end, a small cyclic displacement is applied on a grain in the bulk of a two-dimensional disordered packing under gravity and the displacement fields are monitored. We evidence a dominant long range radial response in the upper half part above the solicitation and after a large number of cycles the response is "quasireversible" with a remanent dissipation field exhibiting long range streams and vortexlike symmetry.
authors.affiliation: Laboratoire des Milieux Désordonnés et Hétérogènes, UMR 7603, Université Pierre et Marie Curie, Boîte 86, 4 Place Jussieu, 75252 Paris Cedex 05, France.
authors.forename: Evelyne
authors.initials: E
authors.lastname: Kolb
authors.forename: Jean
authors.initials: J
authors.lastname: Cviklinski
authors.forename: José
authors.initials: J
authors.lastname: Lanuza
authors.forename: Philippe
authors.initials: P
authors.lastname: Claudin
authors.forename: Eric
authors.initials: E
authors.lastname: Clément