Résumé:
This letter shows an unexpected phenomenon for surface acoustic waves (Rayleigh waves) propagating on a solid cylinder. It was observed that a short Rayleigh wave pulse was reversed during its propagation. In experiments on duraluminium and steel cylinders, transient surface acoustic waves (SAW) were launched by a pulsed YAG laser focused along a line. The radial component of the displacement was measured by a heterodyne optical interferometer. The waveforms recorded versus the angle  between the source and the detection point shows that the Rayleigh pulse, which is monopolar (positive) near the source, becomes bipolar at  = 45° and monopolar (negative) at  = 90°. An analytical calculation taking into account the dispersive effect reproduces waveforms whatever the propagation distance. A physical model is proposed to account for the reversal of the acoustic pulse.

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