Sound wave scattering by circular cylindrical shells

The symmetric ( S 0) and antisymmetric ( A 0) Lamb-type waves generated in a thin elastic cylindrical shell by normal incidence of an acoustic wave have been considered. The typical frequency dependencies (FD) of the backscattered acoustic pressure at on observetion point in the far field are presented. The spectra of the S 0 and A 0 waves are marked on them. It was found that if the A 0 wave is excited in the shell, then its phase velocity is greater than the sound velocity in the fluid surrounding the shell. The parameter which defines the center of the strong bending domain (SBD) is defined. It is shown that in this domain the A 0 wave is practically non-dispersive. Phase velocity data for the A 0 wave are given. Spectra and dispersion curves of the S 0 wave for shells which have different relative thickness s and which are made of different materials have been examined.