Windowed displays of broadband impulse response measurements for finite cylindrical shells

Abstract

Previously interpreted angle-frequency domain displays of impulse response measurements for thick nd thin finite cylindrical shells [S. F. Morse et al., J. Acoust. Soc. Am. 101, 3043(A) (1997)] reveal backscattering enhancements due to elastic effects on the cylinder over a range of target tilt angles. Presently, these signatures are examined in the angle-time and time-frequency domains. For selected angles, time-frequency analyses are presented as well as synthetic aperture images for selected apertures. From these it is possible to identify the spatial and angular locations of many of the important elastic contributions. Features associated with a meridional ray, as well as helical rays, have the appearance of originating from the back end of the cylinder. One major elastic reponse observed at large tilt angles is found below the coincidence frequency. [Work sponsored by the Office of Naval Research.]