Dynamic Fracture and Fragmentation of Ice Materials

Abstract

By simultaneously operating high-speed digital video cameras, we have been experimentally investigating the mechanical characteristics of ice spheres that impinge upon a fixed elastic plate consisting of ice/polycarbonate. We have found that, when ruptured under dynamic impact, ice spheres show two specific fracture patterns: “top” and “orange segments.” Our three-dimensional finite difference calculations simulating impact on linear elastic spheres indicate that “top” (“orange segments”) fracture pattern is generated due to a shorter (longer) contact time during the impact process, respectively. Here, using pressure sensors, we try to clarify more quantitatively the generation mechanism of two dynamic fracture patterns. The new experimental observations suggest that the rise time (the time needed to reach a certain pressure owing to impact) is basically shorter when the generated fracture is the “orange segments”-type. This shorter rise time renders a longer effective contact time and hence waves of longer lengths, consistent with our earlier speculations.