9. Defect Characterization: Fundamentals
Let me begin by saying that this is part of a program which is very much complementary to and is helped by the experimental program; so I'll repeat, in part, some of the overview comments that Bruce Thompson made this morning. We've regarded our role as one of trying to plug into the overall program those aspects of the theory of elastic wave scattering which can be developed in a utilitarian way in terms of modern analytical and computational techniques, in a form which I hope can be useful in signal processing, interpretation, design of experiment, etc. To outline our point of view, I'm going to first give a survey of what we have been doing and then give some of the results. It's rather shocking to think of the amount of money that goes into an experimental program and its interpretation, if the interpretation is done in terms of acoustic or scalar wave scattering theories, when the differences from proper elastic theory can be as great as those which Bruce Thompson pointed to this morning.
Krumhansl, J. A.; Domany, E.; Musikar, P.; Teitel, S.; and Wood, D., "Interpretation of Ultrasonic Scattering Measurements by Various Flaws from Theoretical Studies" (1977). Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE, July 1975–September 1976. 33.