RESONANCE IDENTIFICATIONS OF A SOLID AXISYMMETRICAL FINITE-LENGTH TARGET

Acoustic resonance scattering from a water-immersed, solid tungsten ca rbide target in the form of a finite-length circular cylinder terminat ed by two hemispherical endcaps has been studied experimentally, and a nalyzed theoretically. The resonance frequencies have been determined from the condition of phase matching of the generated surface waves en circling the object; for the surface waves propagating over its cylind rical portion in the axial direction, the dispersion has been properly taken into account, as well as that of surface waves on the spherical surfaces. Surface displacements corresponding to the standing waves a t each resonance were determined, and were used to calculate the angul ar patterns of the scattered acoustic field, in excellent agreement wi th the observed angular distributions. The pattern of lobes is found t o provide information on the mode N of the standing surface waves, alt hough in a less straightforward fashion than this had been the case in previous studies for the simple examples of spheres or infinite cylin ders.