Interaction of Propagting Cracks and Shear Waves

Fluctuations in the crack tip structure should result in the release of elastic waves that propagate both into the bulk as well as along the surface. Ramanathan and Fisher (1997), and Morrisey and Rice (1998) examined such wave interactions in a series of increasingly sophisticated models. The possibility that in-plane and out-of-plane perturbations could persist along the crack surface, resulting in new kind of waves crack front waves and corrugation waves was discovered by these authors. Such waves were suggested to be the possible sources of crack surface roughening, even in brittle materials. Sharon et al., (2001) generated dynamically growing cracks in soda lime glass plate specimens; perturbations were introduced by scribing one face of the plate with a 100 1000 μm deep groove. Post-mortem examination of the crack surface indicated surface undulations that emanated from the location of the crack front perturbation, traveled across the width of the specimen, reflected off the opposite specimen surface and bounced back and forth for a distance many times the width of the perturbation. Based on their observations, Sharon et al., (2001) suggested that such undulations were indeed evidence of crack front waves. Here we report on an experimental investigation aimed at examining the interaction between propagating cracks and shear waves (Bonamy and Ravi-Chandar, 2003a, b).