Nature de l'onde d'interface de Scholte sur une coque cylindrique

Abstract
The theoretical and experimental studies of the ultrasonic scattering by cylindrical shells filled with air and immersed in water show, on the backscattering spectra, large amplitude variations. These variations are related to an interface wave called "A wave". The resonances of this wave are detected in a frequential window that depends on the radius ratio (inner radius b/outer radius a). They are observed for cylindrical shells with a radius ratio superior to 0.6. This wave that propagates in the water around the pipe is still not very well know in spite of the investigations which have been devoted to it. In this numerical study, it is proposed a study of the evolution of the frequency of different resonances for cylindrical shells with the radius ratio between 0.2 and 0.95. The interaction between the flexural wave A₀ in the shell and the creeping wave in the fluid around the pipe is studied in greater detail. The dispersion curves of the phase velocity for these waves are presented. They show a repulse area between these two curves. This area is translated toward the high frequencies when the radius ratio tends toward 1. This phenomenon is related to the contact condition at the liquid/shell interface.