Time-frequency analysis of transient high-frequency dispersive guided waves on tilted cylindrical shells: Review

Abstract

Measurements of the back scattering by bluntly truncated tilted cylindrical shells in water reveal a dependence on the aspect angle, which can be interpreted using geometrically described coupling mechanisms [Morse et al., J. Acoust. Soc. Am. 103, 785–794 (1998)]. By exciting a shell with a suitable acoustic pulse localized in time, the recorded backscattering response reveals a significant evolution of the spectrum as a function of time and tilt angle. This evolution was interpreted using the dispersion relations of the relevant high-frequency shell guided waves [Morse and Marston, J. Acoust. Soc. Am. 111, 1289–1294 (2002)]. The coupling conditions are affected by the mode properties. This interpretation was facilitated by also computing the scattering properties of an infinitely long titled shell [Morse and Marston, J. Acoust. Soc. Am. 106, 2597–2600 (1999)] and by measuring and modeling the contributions of helical and meridional rays [Morse and Marston 112, 1318–1326 (2002); Blonigon and Marston, 112, 528–536 (2002)]. One of the shells investigated was also convenient for a quasi-holographic imaging of the bistatic scattering of short pulses [Baik et al., 130, 3838–3851 (2011)]. [Work supported by ONR.]