Phase transition in a static granular system

TL;DR

This study identifies a clear phase transition in a static granular system of glass beads, characterized by a change in shear resistance at a specific particle volume fraction, using fluidization and shear testing methods.

Contribution

It demonstrates the existence of a well-defined phase transition in a static granular system at a specific volume fraction, advancing understanding of granular material behavior.

Findings

Transition occurs at particle volume fraction φ=0.60

Resistance to shear changes sharply at the transition point

Fluidization pulses effectively prepare states with controlled φ

Abstract

We find that a column of glass beads exhibits a well-defined transition between two phases that differ in their resistance to shear. Pulses of fluidization are used to prepare static states with well-defined particle volume fractions $\phi$ in the range 0.57-0.63. The resistance to shear is determined by slowly inserting a rod into the column of beads. The transition occurs at $\phi=0.60$ for a range of speeds of the rod.