Ultrasonic Flaw Classification Using a Quasi-Pulse-Echo Technique
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Begun in 1973, the Review of Progress in Quantitative Nondestructive Evaluation (QNDE) is the premier international NDE meeting designed to provide an interface between research and early engineering through the presentation of current ideas and results focused on facilitating a rapid transfer to engineering development.
This site provides free, public access to papers presented at the annual QNDE conference between 1983 and 1999, and abstracts for papers presented at the conference since 2001.
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Abstract
In solving ultrasonic flaw characterization problems, flaw type information is often needed in order to pursue succeeding tasks such as flaw sizing. In a typical inspection, the interaction of the incident ultrasonic pulse with the flaw results in a series of signal trains. A variety of signal features are extracted from these flaw signals and then used as the basis for the classification process. This classification process is made difficult by the large number of possible scattered waves. For example, typical ultrasonic signals from a planar crack-like defect consist of reflected responses, surface traveling waves, edge diffracted waves and head wave components. For a volumetric void-like defect, the returned signal pattern similarly contains reflected waves of the same mode as well as mode-converted reflections and “creeping” waves. However, in pulse-echo testing a fundamental difference exists between a crack-like flaw and a volumetric flaw that can be used for classification purposes. This difference is reflected in the fact that a significant mode-converted diffracted wave component can exist for a crack-like defect (Fig. 1(a)) which does not exist in pulse-echo testing for a volumetric defect (Fig.1(b)).