RESONANT SCATTERING BY 2 ELASTIC CYLINDRICAL-SHELLS

The resonant scattering by two elastic cylindrical shells immersed in water is theoretically and experimentally studied. The shell axis are parallel; the incident plane wave direction of propagation is perpendi cular to the shell axis. The scattering by the two shells is rewritten in a new way explaining the interferential behavior which is experime ntally observed in the scattering process. The analysis of the scatter ing in terms of multiple interactions is also performed in order to ev aluate the strength of the coupling between the two shells in relation to the gap between them. A numerical calculation of the temporal and frequency responses of the target submitted to an impulsive excitation is compared with experimental data obtained when the shells are align ed with regard to the incident wave direction of propagation. The agre ement between the experimental and theoretical results is very good. S ingle shell resonances and ''interaction resonances'' related to the i nterferential behavior are detected. The geometrical and circumferenti al waves involved in the scattering process are also studied in order to explain the temporal and frequential responses.