Decompaction wave propagation in a vibrated fine-powder bed

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.

Automated summary

This study experimentally investigates crack formation and decompaction-wave propagation in a vibrated powder bed consisting of 5 μm glass beads. The vibrated powder bed demonstrates three distinct phases under different vibration conditions: consolidation, static fracture, and dynamic fracture. Notably, when the powder bed is strongly vibrated, an upward wave propagation is observed in the dynamic fracture regime. An interesting finding is that in fine cohesive powders, the decompaction-wave propagation speed, normalized to gravitational speed, is independent of the vibration strength. This suggests that the wave propagation speed is influenced by the balance between gravity and cohesion effect rather than vibration strength. The universality of the wave propagation phenomenon in coarser and low-density granular powders is also explored.