title: Hot spots in an athermal system.
abstract: We study experimentally the dynamical heterogeneities occurring at slow shear, in a model amorphous glassy material, i.e., a 3D granular packing. The deformation field is resolved spatially by using a diffusive wave spectroscopy technique. The heterogeneities show up as localized regions of strong deformations spanning a mesoscopic size of about 10 grains and called the "hot spots." The spatial clustering of hot spots is linked to the subsequent emergence of shear bands. Quantitatively, their appearance is associated with the macroscopic plastic deformation, and their rate of occurrence gives a physical meaning to the concept of "fluidity," recently used to describe the local and nonlocal rheology of soft glassy materials.
authors.affiliation: Institut de Physique de Rennes (UMR UR1-CNRS 6251), Université de Rennes 1, Bâtiment 11A, Campus de Beaulieu, F-35042 Rennes, France.
authors.forename: Axelle
authors.initials: A
authors.lastname: Amon
authors.forename: Van Bau
authors.initials: VB
authors.lastname: Nguyen
authors.forename: Ary
authors.initials: A
authors.lastname: Bruand
authors.forename: Jérôme
authors.initials: J
authors.lastname: Crassous
authors.forename: Eric
authors.initials: E
authors.lastname: Clément