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Star-Shaped Crack Pattern of Broken Windows

2013; American Physical Society; Volume: 110; Issue: 17 Linguagem: Inglês

10.1103/physrevlett.110.174302

1092-0145

Nicolas Vandenberghe, Romain Vermorel, Emmanuel Villermaux,

Image Processing and 3D Reconstruction

Broken thin brittle plates like windows and windshields are ubiquitous in our environment. When impacted locally, they typically present a pattern of cracks extending radially outward from the impact point. We study the variation of the pattern of cracks by performing controlled transverse impacts on brittle plates over a broad range of impact speed, plate thickness, and material properties, and we establish from experiments a global scaling law for the number of radial cracks incorporating all these parameters. A model based on Griffith's theory of fracture combining bending elastic energy and fracture energy accounts for our observations. These findings indicate how the postmortem shape of broken samples are related to material properties and impact parameters, a procedure relevant to forensic science, archaeology, or astrophysics.