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Friday, January 11, 2013
1:00 PM - 2:00 PM
CNLS Conference Room (TA-3, Bldg 1690)

Seminar

Frictional Jamming Crossover

Stefanos Papanikolau
Dept. of Physics, Yale University

Mechanically stable packings of frictionless disks with contact interactions form through fast quenches at random close packing (RCP). However, for frictional particles with static friction coefficient μ greater than μ*, the packing density slides toward random loose packing (RLP) at large friction. I will discuss how the crossover from random close to random loose packing can be explained by identifying a novel geometric phase transition through simulations of frictional bidisperse disks. The rotational content of low energy vibrational modes at jamming onset drastically changes from co-rotating contacting particles for low friction to counter-rotating, gear-like, for μ greater than μ* and the groups of particles with gear-like dynamical contributions percolate at μ*. The emergence of this "gear rigidity" transition provides deep insights for possible universal mechanisms to optimize the density of random packings.

Host: Cynthia Reichhardt,