Backscattering enhancements due to reflection of meridional leaky Rayleighwaves at the blunt truncation of a tilted solid cylinder in water: Observations and theory

Leaky surface waves once launched on an elastic object in water will underg o partial reflection at the truncations of the object. Under certain condit ions, such reflections can radiate locally flat acoustic wavefronts with a reversal of the acoustic wave vector, and thus a large backscattered signal is produced. A stainless-steel circular rod with flat ends was ensonified through an angular region appropriate for launching meridional Rayleigh wav es, and the resulting backscattering enhancement is consistent with the hyp othesized end-reflection process. The observed backscattering peak is in ge neral agreement with predictions from a convolution formulation [P. L. Mars ton, J. Acoust. Sec. Am. 102, 358-369 (1997)]. The tilt of the cylinder was varied to explore the peak's width, and the results are consistent with an extension of the theory for the dephasing of the Rayleigh wave given here. The amplitude measurements used ultrasonic tone bursts having ka of 50 and 83, and the enhancement is predicted to be significant over a wide range o f ka. (C) 1999 Acoustical Society of America. [S0001-4966(99)02910-0].