Accession Number:

ADA256018

Title:

Experimental Investigation of Scattering from Randomly Rough Plastic Cylinders

Descriptive Note:

Master's thesis

Corporate Author:

WOODS HOLE OCEANOGRAPHIC INSTITUTION MA

Personal Author(s):

Report Date:

1992-09-01

Pagination or Media Count:

115.0

Abstract:

Acoustical backscattering from randomly rough infinitely long elastic cylinders surrounded by a fluid medium is examined. The cylinder radius is allowed to vary along its lengthwise axis creating one-dimensional rotationally symmetric roughness. Using recently published rough cylinder formulations T.K. Stanton, J. Acoust. Soc. Am., 92, 1641-1664 1992 and T.K. Stanton and D. Chu, J. Acoust. Soc. Am., 92, 1665-1678 1992, explicit expressions are derived for the backscattered field for a laboratory pulse-echo environment spherically spreading directional source and receiver with arbitrary beam patterns. Efficient numerical integration algorithms are developed to solve for the backscattered field from a specified surface profile. Experimental measurements from dense elastic stainless steel cylinders immersed in water are presented to quantitatively illustrate the effects of small scale surface roughness sigmaa 0.0131 where sigma, is the surface rms roughness and a is the mean cylinder radius for 4.5 ka 70 where k is the acoustic wavenumber. The actual target surface profile is well described and used as an input in the numerical simulations. Agreement is found between measurements and simulation predictions both in the mean field levels and the field fluctuations over a wide range of frequencies.

Subject Categories:

  • Structural Engineering and Building Technology
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE