Transient scattering of SH waves by surface-breaking and sub-surface cracks

The transient scattering of SH waves by surface-breaking and sub-surface cracks normal to the free surface of a half-space is investigated. The problem is first solved in the frequency domain by an efficient hybrid method which combines the finite element method (FEM) with the boundary integral representation (BIR). The transient responses are then obtained by inverting the spectra via fast Fourier transform (FFT) routine. The shape of the incident pulse is a Ricker wavelet. Graphical results are presented for the surface displacements, crack opening displacements, and dynamic stress intensity factors to show the significant effects due to the presence of the cracks. The wave propagation can be clearly observed, so that the mechanism of SH-wave scattering by cracks can be easily understood by this study. Furthermore, the scattered waves received on the free surface can be used successfully to detect the location, length, and depth of the crack. 0 1997 Elsevier Science Ltd.