ASA 124th Meeting New Orleans 1992 October

2pSA5. Improved determination of the relative strengths of resonances excited for plane waves scattered from elastic spheroids.

C. E. Dean

Code 221, NRL, Stennis Space Center, MS 39529-5004

Dept. of Phys., Georgia Southern Univ., Landrum Box 8031, Statesboro, GA 30460

M. F. Werby

Code 221, NRL, Stennis Space Center, MS 39529-5004

In a previous paper [C. E. Dean and M. F. Werby, J. Acoust. Soc. Am. 91, 2469 (1992)] initial calculations for scattering from spheroids composed of six materials for aspect ratios of three and six were presented. Improved results for the same cases are now shown. The difference in resonance locations as a function of material properties is noted and explained in terms of the pseudo-Rayleigh type resonances described extensively in the literature for spheroids. There is also a marked difference between the amplitudes of the resonances. The relative amplitudes of the resonances is predicted as a function of material properties based on the Rayleigh wave interpretation of these resonances. A theory is developed based on the fact that Rayleigh type resonances can only be excited as a function of the appropriate grazing annular region. This region is determined as a function of the material property and geometry. Numerous results are presented.