Decompaction-wave propagation in a vibrated fine powder bed

TL;DR

This study experimentally investigates crack formation and decompaction-wave propagation in vibrated fine powder beds, revealing a universal wave speed governed by gravity and cohesion, independent of vibration strength.

Contribution

It uncovers the independence of decompaction-wave speed from vibration strength in fine cohesive powders and explores universality across different granular materials.

Findings

Wave propagation speed is independent of shaking strength in fine powders.

Three phases identified: consolidation, static fracture, dynamic fracture.

Universal behavior observed across different granular powders.

Abstract

We experimentally study the crack formation and decompaction-wave propagating in a vibrated powder bed consisting of glass beads of 5 {\mu}m in diameter. The vibrated powder bed exhibits three distinct phases depending on the vibration conditions: consolidation (CS), static fracture (SF), and dynamic fracture (DF). Particularly, we found an upward wave propagation in the DF regime when the powder bed is strongly vibrated. As a remarkable feature, we found that in fine cohesive powders, the decompaction-wave propagation speed normalized to gravitational speed is independent of the shaking strength. This result implies that the wave propagation speed is governed by the balance between gravity and cohesion effect rather than vibration strength. We also explore the universality of wave propagation phenomenon in coarser and low-density granular powders.