Local and global avalanches in a 2D sheared granular medium

Jonathan Barés (1, 2, 3) , Dengming Wang (4) , Dong Wang (3) , Thibault Bertrand (5) , Corey S O 'Hern (5, 6, 7) , Robert Behringer (3)

1 LMGC - Laboratoire de Mécanique et Génie Civil
2 PMMD - Physique et Mécanique des Milieux Divisés
3 Department of Physics & Center for Nonlinear and Complex Systems
4 Key Laboratory of Mechanics on Western Disaster and Environment
5 Department of Mechanical Engineering and Materials Science
6 Departments of Applied Physics [New Haven]
7 Department of Applied Physics, Yale University

We present the experimental and numerical studies of a 2D sheared amorphous material constituted of bidisperse photo-elastic disks. We analyze the statistics of avalanches during shear including the local and global fluctuations in energy and changes in particle positions and orientations. We find scale free distributions for these global and local avalanches denoted by power-laws whose cutoffs vary with inter-particle friction and packing fraction. Different exponents are found for these power-laws depending on the quantity from which variations are extracted. An asymmetry in time of the avalanche shapes is evidenced along with the fact that avalanches are mainly triggered from the shear bands. A simple relation independent from the intensity, is found between the number of local avalanches and the global avalanches they form. We also compare these experimental and numerical results for both local and global fluctuations to predictions from meanfield and depinning theories.

Mots clés: granular matter; earthquake; shear jamming; crackling dynamics; photoelasticity; local avalanche

Domaines: Matériaux; Mécanique des matériaux [physics.class-ph]

Jonathan Barés, Dengming Wang, Dong Wang, Thibault Bertrand, Corey S O 'Hern, et al.. Local and global avalanches in a 2D sheared granular medium. Physical Review E , 2017, 96, pp.052902. ⟨10.1103/PhysRevE.96.052902⟩. ⟨hal-01650149⟩