Monday, June 1

The Wave Mechanics of Acoustic Microscopy

8:00 AM-8:45 AM
Chair: Graeme Fairweather, Colorado School of Mines
Room 246

Applications of ultrasonic techniques in non-destructive evaluation have evolved from detection and imaging to quantitative characterization. An example is the quantitative mode of line-focus acoustic microscopy, which has become a very useful technique for the determination of surface wave speeds and thereby the elastic constants of an anisotropic thin film deposited on an anisotropic elastic substrate. The determination of these constants is generally based on the measurement of the V(z) curve, which is the record of the modulus of the measured voltage as a function of the distance z between the focus of the lens and the surface of the specimen. The procedure has three essential components: 1) the measurement of the V(z) curve, 2) the development of a theoretical measurement model for parametric studies of V(z) curves, and 3) a procedure to obtain the elastic constants by systematic comparison of wave mode velocities obtained from the theoretical model and the V(z) measurements. The speaker will discuss the use of elastodynamic theory for anisotropic solids to develop a measurement model for line-focus acoustic microscopy, which will then be used to determine elastic constants from measured V(z) curves.

Jan D. Achenbach
Center for Quality Engineering and Failure Prevention, Northwestern University

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tjf, 12/18/97