Diffraction of transient elastic waves in a plate with a cylindrical cavity

In this paper, the diffraction of transient elastic waves in a plate structure with a circular cavity is studied both numerically and experimentally. The heterogeneous finite difference formulation was utilized to simulate the propagation of transient plane strain (or plane stress) waves in a plate with a circular cylindrical cavity due to a point dynamic impulse on the surface. Snap-shots as well as the seismograms of the diffraction wave fields are given. The focusing of the elastic waves due to the presence of a circular cavity was identified. Transient elastic wave experiment in a thin aluminum plates (plane stress) with a circular cavity was also conducted via the utilization of the laser-ultrasonic technique. The features of measured seismogram of the aforementioned diffractions due to the circular cavity in a plate are in accordance with those of the numerical simulated results. It is noted that with a higher frequency source and small aperture receivers, the present study can serve as a basis for the detections of small defects in plate structures.