Interaction of Horizontal Shear Waves With a Running Crack

An analysis of the scattering of horizontally polarized shear waves by a finite crack extending uniformly is carried out. It is based on the extension of the integral equation method used by the authors in wave diffraction problems dealing with stationary lines or surfaces of discontinuity. The distortion of the local stress pattern due to the motion of the crack is determined for incident waves impinging on the crack in an arbitrary direction. It is found that the intensity factor of the singular stresses depends sensitively upon the speed of crack propagation, the frequency of the incoming waves, and the angle of incidence. As the crack speed is increased at normal incidence, the peaks of the intensity-factor curves tend to decrease and to occur at lower wave numbers. Quantitative assessment of the effect of the aforementioned system parameters on the stress and displacement fields is made by displaying the numerical results graphically.