ACOUSTIC SCATTERING FROM A CYLINDRICAL-SHELL BOUNDED BY HEMISPHERICALENDCAPS - RESONANCE INTERPRETATION WITH SURFACE-WAVES PROPAGATING IN CYLINDRICAL AND SPHERICAL-SHELLS

The studies of the acoustic scattering from infinite cylinders or sphe res have shown the strong influence of the propagation of surface wave s. Two types of surface waves are distinguished: the Rayleigh or Whisp ering Gallery waves and the Scholte-Stoneley wave. In this paper, theo retical and experimental results obtained on objects constituted by a cylindrical shell bounded by two hemispherical shells are presented, w hen these objects are insonified in the direction parallel to their ma in axis. To explain the experimental results, the stationary condition is written in the meridian plane of these objects. To apply this cond ition, the phase velocities of the waves propagating in the cylindrica l and in the spherical parts must be known. First, the phase velocity of waves propagating along the length of cylindrical shells is theoret ically and experimentally studied. Then an experimental study of the p hase velocities of the waves propagating on spherical shells is carrie d out. Finally, the results of these two studies are used to explain t he acoustic behavior of objects constituted by a cylindrical shell bou nded by two hemispherical endcaps in the case of axial excitation.