Local and Global relations between the number of contacts and density in monodisperse sphere packs

TL;DR

This study investigates the relationship between contact networks and density in monodisperse sphere packs, revealing how local and global structures evolve with packing density and influence deformation behavior.

Contribution

It provides new insights into the correlation between local packing configurations and overall density, using three methods to analyze contact networks in sphere packs.

Findings

Coordination number exceeds 4 and increases with density

Positive correlation between local packing fraction and number of neighbors

Local configurations with few neighbors can deform plastically during compaction

Abstract

The topological structure resulting from the network of contacts between grains (\emph{contact network}) is studied for large samples of monosized spheres with densities (fraction of volume occupied by the spheres) ranging from 0.59 to 0.64. We retrieve the coordinates of each bead in the pack and we calculate the average coordination number by using three different methods. We show that, in the range of density investigated, the coordination number is larger than 4 and it increases with the packing fraction. At local level we also observe a positive correlation between local packing fraction and number of neighbors. We discover a dependence between the local densities of configurations with few neighbors in contact and the global sample-denities. This might indicate that local configurations with small number of neighbors are able to deform plastically when the sample is compactifying. PACS: 45.70.-n, Granular Systems; 45.70.Cc, Static sandpiles; Granular Compaction.