Phys Rev Lett. 2020 Jan 24;124(3):038004. doi: 10.1103/PhysRevLett.124.038004.

Pressure Dependent Shear Response of Jammed Packings of Frictionless Spherical Particles.

Physical review letters

Kyle VanderWerf, Arman Boromand, Mark D Shattuck, Corey S O'Hern

PMID: 32031840 DOI: 10.1103/PhysRevLett.124.038004

Abstract

The mechanical response of packings of purely repulsive, spherical particles to athermal, quasistatic simple shear near jamming onset is highly nonlinear. Previous studies have shown that, at small pressure p, the ensemble-averaged static shear modulus ⟨G-G_{0}⟩ scales with p^{α}, where α≈1, but above a characteristic pressure p^{**}, ⟨G-G_{0}⟩∼p^{β}, where β≈0.5. However, we find that the shear modulus G^{i} for an individual packing typically decreases linearly with p along a geometrical family where the contact network does not change. We resolve this discrepancy by showing that, while the shear modulus does decrease linearly within geometrical families, ⟨G⟩ also depends on a contribution from discontinuous jumps in ⟨G⟩ that occur at the transitions between geometrical families. For p>p^{**}, geometrical-family and rearrangement contributions to ⟨G⟩ are of opposite signs and remain comparable for all system sizes. ⟨G⟩ can be described by a scaling function that smoothly transitions between two power-law exponents α and β. We also demonstrate the phenomenon of compression unjamming, where a jammed packing unjams via isotropic compression.

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• Journal Article