ASA 124th Meeting New Orleans 1992 October

5aSA11. Time, frequency, and aspect analysis of bistatic scattering from a hemispherically end-capped steel cylindrical shell immersed in water.

Timothy J. Yoder

SFA, Inc., 1401 McCormick Dr., Landover, MD 20785

Charles Gaumond

Angie Sarkissian

Naval Res. Lab., Washington, DC 20375

A finite element simulation of a hemispherically end-capped steel cylindrical shell, immersed in water, and end-ensonified by plane acoustic waves is shown for a frequency band from ka=2.0 to ka=6.0. The bistatic far-field acoustic scattering from this simulation is determined by the following physical processes: the quasilongitudinal wave, the shear wave, specular reflection, and wave-vector matching with the radiation medium. The time, frequency, and aspect dependence of the bistatic far-field acoustic scattering is graphically analyzed to determine the physical process or combination of processes responsible for the scattering. This analysis reveals the location on the structure that scatters energy into a particular far-field highlight, the time that the structure scatters the energy, and the frequency dependence of the scattered energy. The transport of energy down the shell and the reflection of energy from the ends of the shell are also demonstrated through this analysis.