Acoustic backscatter from materials with rough surfaces and finite size microstructure: Theory

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Journal of the Acoustical Society of America

DOI:https://doi.org/10.1121/1.418006· OSTI ID:489274

Bilgen, M ^[1]; Rose, J H ^[2]

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1. Department of Radiology, University of Kansas Medical Center, Kansas City, Kansas 66160 (United States)
2. Center for NDE, Iowa State University, Ames, Iowa 50011 (United States)

Surface roughness changes the acoustic backscatter signal due to the microstructure of a sample. These changes have been previously reported for the backscatter power under the restrictive assumption that the microstructural length scales are much smaller than any other length scale in the problem. In this study this restriction is removed and an approximate analytic series solution is presented that describes the effects of surface roughness on the power and mean square of the acoustic backscatter from samples whose microstructure is characterized by an autocorrelation length L{sub m}, which may be smaller than, comparable to, or larger than either the wavelength or the autocorrelation length L{sub s} that describes the surface roughness. Both focused and unfocused phase-sensitive transducers are considered. A surprising result emerged. For focused probes at normal incidence and for moderate roughness, the backscattered power at the focal depth is almost entirely determined by the frequency and the rms surface height; it is independent of L{sub m}, L{sub s}, and the radius of the transducer. {copyright} {ital 1997 Acoustical Society of America.}

• OSTI ID: 489274
• Journal Information: Journal of the Acoustical Society of America, Journal Name: Journal of the Acoustical Society of America Journal Issue: 1 Vol. 101; ISSN 0001-4966; ISSN JASMAN
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ACOUSTIC TESTING
BACKSCATTERING
MATERIALS TESTING
MICROSTRUCTURE
NONDESTRUCTIVE TESTING
ROUGHNESS
SURFACES
TRANSDUCERS
ULTRASONIC TESTING