Force mobilization and generalized isostaticity in jammed packings of fractional grains

Shundyak, K.; Hecke, M.L. van; Saarloos, W. van (2007)

Article / Letter to editor

We show that in slowly generated two-dimensional packings of frictional spheres, a significant fraction of the friction forces lie at the Coulomb threshold—for small pressure p and friction coefficient μ, 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 μ. 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 μ.

• All authors: Shundyak, K.; Hecke, M.L. van; Saarloos, W. van
• Date: 2007-01-31
• Journal: Physical Review E
• Volume: 75
• Issue: 1
• Pages: 010301
• DOI: doi:10.1103/PhysRevE.75.010301