title: Onset of mechanical stability in random packings of frictional spheres.
abstract: Using sedimentation to obtain precisely controlled packings of noncohesive spheres, we find that the volume fraction phiRLP of the loosest mechanically stable packing is in an operational sense well defined by a limit process. This random loose packing volume fraction decreases with decreasing pressure p and increasing interparticle friction coefficient mu. Using x-ray tomography to correct for a container boundary effect that depends on particle size, we find for rough particles in the limit p-->0 a new lower bound, phiRLP=0.550+/-0.001.
authors.affiliation: Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Jerkins
authors.forename: Matthias
authors.initials: M
authors.lastname: Schröter
authors.forename: Harry L
authors.initials: HL
authors.lastname: Swinney
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Senden
authors.forename: Mohammad
authors.initials: M
authors.lastname: Saadatfar
authors.forename: Tomaso
authors.initials: T
authors.lastname: Aste