超弾性的挙動を示すゴム材料における超音速破壊現象の実験的研究

概要

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Rupture speeds (Mach numbers) obtained by ordinary laboratory fracture experiments using monolithic brittle linear elastic materials are by far lower than those predicted by classical theories of mechanics and inferred from seismic inversions. Some seismological recordings even imply the existence of supersonic (supershear) rupture speeds. Here, in order to possibly explain these discrepancies, dynamic mode-I fracture in hyperelastically behaving rubber materials is experimentally investigated. Utilizing a high-speed digital video camera system, rupture (crack) initiation and propagation process is recorded. The preliminary results clearly show that if the magnitude of static crack-parallel stress is relatively large and comparable to that of remote mode-I loading stress, the crack propagates surprisingly straight and, even without the existence of material heterogeneities, the crack front accelerates from subsonic to a constant supersonic speed to capture the wave front generated upon rupture initiation.