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Title:Model of confocal ultrasonic inspection system for interfaces
Author(s):Yogeswaren, Elankanayakam; Harris, John G.
Subject(s):Ultrasonic Inspection
Abstract:A mathematical model describing how a confocal arrangement of two focused ultrasonic transducers is used to interrogate a complex interface between two solid materials by scanning the focal point across the interface is outlined. A complex interface is one that has roughness and partial contact at many length scales most of which are equal to or smaller than the compressional or shear wavelength in the material. When the focused ultrasound strikes such an interface, though the focal region be small, strong multiple scattering takes place among scatterers within and adjacent to the focal region making it unclear exactly how the interface is being sampled. To clarify this issue a specific interface model consisting of multiple, small cracks having arbitrary lengths and spacings is used. This interface is interrogated by an anti-plane, focused shear wave. From this model it is possible to show that what is measured are the multiple scattered signals averaged over the aperture of the transducer, but that the dominant contribution comes from the scattered signals that phase match to the interrogating signal. Explicit expressions relating the modeled reflected and transmitted signals to the convolution of the incident wavefield with the crack-opening displacements at the focal region are given. Numerical examples are worked out for similar and contrasting materials on each side of the interface.
Issue Date:1993-09
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 726
Genre:Technical Report
Sponsor:National Science Foundation 93/09
Rights Information:Copyright 1993 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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