Force Mobilization and Generalized Isostaticity in Jammed Packings of Frictional Grains

Abstract

We show that in slowly generated 2d packings of frictional spheres, a significant fraction of the friction forces lies at the Coulomb threshold - for small pressure p and friction coefficient mu, about half of the contacts. Interpreting these contacts as constrained leads to a generalized concept of isostaticity, which relates the maximal fraction of fully mobilized contacts and contact number. For p->0, our frictional packings approximately satisfy this relation over the full range of mu. This is in agreement with a previous conjecture that gently built packings should be marginal solids at jamming. In addition, the contact numbers and packing densities scale with both p and mu.

4 pages, 4 figures, submitted

References in corpus (4)

• Jamming at Zero Temperature and Zero Applied Stress: the Epitome of Disorder
• Critical scaling in linear response of frictionless granular packings near jamming
• Stationary state volume fluctuations in a granular medium
• Elastic wave propagation in confined granular systems

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