2017/07/21 by Ishan Prasad, Christian D. Santangelo, Gregory M. Grason · 1 citation
Physics and Astronomy · #cond-mat.soft #cond-mat.dis-nn #cond-mat.stat-mech
paper · pdf · doi:10.1103/physreve.96.052905
published as Phys. Rev. E 96, 052905 (2017) · 12 pages, 7 figures
arxiv created 2017/07/21 · arxiv updated 2017/11/29
We study the influence of particle size asymmetry on structural evolution of randomly jammed binary sphere mixtures with varying large-sphere/small-sphere composition. Simulations of jammed packings are used to assess the transition from large-sphere dominant to small-sphere dominant mixtures. For weakly asymmetric particle sizes, packing properties evolve smoothly, but not monotonically, with increasing small sphere composition, f. Our simulations reveal that at high values of ratio α of large to small sphere radii, (α≥ αc ≈ 5.75) evolution of structural properties such as packing density, fraction of jammed spheres and contact statistics with f exhibit features that suggest a sharp transition, either through discontinuities in structural measures or their derivatives. We argue that this behavior is related to the singular, composition dependence of close-packing fraction predicted in infinite aspect ratio mixtures α→∞ by the Furnas model, but occurring for finite values range of α above a critical value, αc ≈ 5.75. The existence of a sharp transition from small- to large-f values for α≥ αc can be attributed to the existence of a \it sub-jamming transition of small spheres in the interstices of jammed large spheres along the line of compositions fsub(α). We argue that the critical value of finite size asymmetry αc ≃ 5.75 is consistent with the geometric criterion for the transmission of small sphere contacts between neighboring tetrahedrally close packed interstices of large spheres, facilitating a cooperative sub-jamming transition of small spheres confined within the disjoint volumes.