2007/03/02 by Hiroaki Katsuragi, H. Katsuragi, D. J. Durian · 4 citations
Engineering · Materials Science · Physics and Astronomy · #Aerospace engineering #Ballistics #Classical mechanics #Drag #Granular flow and fluidized beds #Granular material #High-Velocity Impact and Material Behavior #Inertial frame of reference #Internal ballistics #Mechanics #Physics #Planetary Science and Exploration #Projectile #Range (aeronautics) #cond-mat.soft
paper · pdf · doi:10.1038/nphys583
published as Nature Physics 3, 420-423 (2007)
arxiv created 2007/03/02 · openalex publication_date 2007/04/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Experiments on the low-speed impact of solid objects into granular media have been used both to mimic geophysical events and to probe the unusual nature of the granular state of matter. Observations have been interpreted in terms of conflicting stopping forces: product of powers of projectile depth and speed; linear in speed; constant, proportional to the initial impact speed; and proportional to depth. This is reminiscent of high-speed ballistics impact in the 19th and 20th centuries, when a plethora of empirical rules were proposed. To make progress, we developed a means to measure projectile dynamics with 100 nm and 20 us precision. For a 1-inch diameter steel sphere dropped from a wide range of heights into non-cohesive glass beads, we reproduce prior observations either as reasonable approximations or as limiting behaviours. Furthermore, we demonstrate that the interaction between projectile and medium can be decomposed into the sum of velocity-dependent inertial drag plus depth-dependent friction. Thus we achieve a unified description of low-speed impact phenomena and show that the complex response of granular materials to impact, while fundamentally different from that of liquids and solids, can be simply understood.