When a dynamic crack propagates through material heterogeneities (material differences), elastic waves are emitted to disturb the crack and change the morphology of the fracture surface. When a crack propagates along preferential cleavage planes of asperity-free (roughness-free) crystalline materials, researchers expect a smooth crack front and a mirror-like fracture surface. In a new report now published on the Proceedings of the National Academy of Sciences (PNAS), Ming Wang and a research team in Mechanics at the French National Center for Scientific Research (CNRS) in France, the Huazhong University of Science and Technology and the Hubei Key Laboratory in Wuhan, China, showed characteristic crack propagation in a single crystalline silicon without material asperities (material roughness). The crack front presented a local kink during high speed crack propagation and generated periodic fracture surface corrugations or ripples. The phenomena grew from angstrom (Å) amplitude to a few hundred nanometres (nm) to propagate with a long lifetime at a frequency-dependent speed and with a scale-dependent shape. The local front oscillations presented the characteristic of solitary waves and Wang et al. named the nonlinear elastic waves “corrugation waves.”
Click here for original story, Self-emitted surface corrugations in dynamic fracture of silicon single crystal
Source: Phys.org