History of Acoustical Imaging
A historical snapshot is presented of the development of acoustical imaging in the context of a Research Program in Quantitative Non-Destructive Evaluation (QNDE). This was an interdisciplinary program involving researchers at the Rockwell Science Center and several other institutes at universities, government laboratories, and industries. This program was first initiated by the Wright Patterson Air Force Base and continued by the Defense Advanced Research Projects Agency. The main objective of the program was to develop techniques of non-destructive testing and give them a strong theoretical underpinning to render them as quantitative as possible. Thus in ultrasonic testing the objective was to combine the traditional manual search for flaws with computer automated search and elastic scattering theory to provide quantitative data on location, size, shape, and orientation. This approach led to several schemes to solve the Inverse Scattering Problem or the reconstruction of a flaw from just a few reflected ultrasonic echoes. Early efforts led to successes with idealized man-made flaws consisting of single and compound flaws embedded in Titanium-alloy. Later this work produced results with naturally occurring flaws in aerospace components.
KeywordsElastic Wave Crack Edge Impulse Response Function Acoustical Image Spherical Void
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