Acoustic resonances of thin cylindrical shells and the resonance scattering theory

An experimental and theoretical study is presented of the properties of circumferential waves on thin‐walled elastic, air‐filled cylindrical shells immersed in water, and of their excitation by normally incident acoustic pulses of short duration. A spectral decomposition of the multiple echo pulses using the Numrich–de Billy method, and subsequent analysis by the resonance scattering theory (RST), reveal for an aluminum shell the presence of an l=2 wave that can be identified with the S0 Lamb wave on a plate, and of an l=0 wave that at low frequencies corresponds to a water‐borne circumferential wave, not given by the Lamb theory of free‐plate vibrations but by its extension to a plate with one‐sided fluid loading. Calculations of complex pole resonances on aluminum and steel shells, as well as of the corresponding circumferential wave speeds and attenuations, serve to clarify the physical situation.