INTERACTION OF AN ACOUSTIC PLANE WAVE WITH A PLANE ELASTIC LIMITED PLATE IN WATER. INTERFEROMETER STUDY OF THE VIBRATION

摘要

The experimental investigation of the interaction of an acoustic plane wave with a limited plane elastic plate is presented. The experimental set-up consists of a duraluminum 2 millimeters thick and 60 mm broad plate. Impulsionnal monostatic and quasi-harmonic or impulsionnal bistatic experiments are performed. In the first case we have calculated the FFT of the diffracted signal for each observation direction, that allows us to compare the experimental Lamb wave angular dispersions curves in a limited plate with the theoretical infinite plate curves. In the second experiment we have measured the scattered field in the forced regime with the second transducer for an incidence angle of 20 degrees. In the same configuration with impulsive incident wave, the waves are observed during their propagation with the use of a laser vibrometer. Temporal and spatial FFT are then performed. This new analysis of surface waves allows us to describe the propagation in each direction.