Nanosecond shock wave-induced surface acoustic waves and dynamic fracture at fluid-solid boundaries

We investigate the generation and propagation characteristics of leaky Rayleigh waves (LRWs) caused by a spherical shock wave incident on a water-glass boundary both experimentally and numerically. The maximum tensile stress produced on the solid boundary is attributed to the dynamic interaction between the LRWs and an evanescent wave generated concomitantly along the boundary. The resultant tensile stress field drives the initiation of crack formation from pre-existing surface flaws and their subsequent extension along a circular trajectory, confirmative with the direction of the principal stress on the boundary. We further demonstrate that this unique ringlike fracture pattern, prevalent in damage produced by high-speed impact, can be best described by the Tuler-Butcher criterion for dynamic failure in brittle materials. The orientation of the ring fracture extension into the solid also follows closely with the trajectory of the local maximum tensile stress distribution.