Accession Number:

ADA257257

Title:

Scattering and Radiation by Shells and Nonlinear Acoustics of Particle Suspensions

Descriptive Note:

Final rept. 15 Jul 1989-30 Sep 1992

Corporate Author:

WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS

Personal Author(s):

Report Date:

1992-10-23

Pagination or Media Count:

69.0

Abstract:

The research reported concerns three main areas a Surface Guided Wave Contributions to the Scattering of Sound by Elastic Shells in Water Quantitative ray representations described for the scattering by shells give insight into the coupling of sound with structures. backscattering enhancement near the coincidence frequency was observed, modeled, shown to be due to a subsonic wave. Aspects of a high-frequency enhancement were investigated along with time-frequency spectrograms of the impulse response. b Radiation Mechanisms for Evanescent Tone Bursts on Fluid Loaded Membranes and Plates Subsonic flexural waves on unbounded plates ordinarily produce evanescent wavefields in the surrounding fluid that are trapped to the plate. Two mechanisms for radiating sound were investigated experimentally a diffraction by a rigid barrier in an evanescent field in air and b transition radiation produced when a wave packet travels down a vertical plate through a water surface. c Acoustical Four-Wave Mixing in Suspensions Sound is shown to interact with sound in a suspension of microspheres. The spheres are attracted to pressure nodes of counter-propagating pump waves. The banded suspension acts as a diffraction grating and scatters a probe-wave when a Bragg condition is satisfied. Acoustical Scattering, Ray Methods, Elastic Shells, Evanescent Waves, Plates, Suspensions, Nonlinear Acoustics, Radiation Pressure.

Subject Categories:

  • Structural Engineering and Building Technology
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE