Metal deformation, acoustic

Thompson, R. B., Li. Y., Spitzig, W. A., Briggs, G. A. D Fagan, A. F., and Kushibiki, J. (1990a). Characterization of the texture of heavily deformed metal-metal composites with acoustic microscopy. In Review of progress in quantitative nondestructive evaluation, Vol. 9 (ed. D. O. Thompson and D. E. Chimenti), pp. 1433-40. Plenum Press, New York. [245]... 

All the information of interest is contained in the acoustic source function. The theory works well for low-velocity impacts where the collisions are elastic but may be extended with some modifications to include plastic deformation. The method is nonempiri-cal (requiring no independent calibration). However, the measurement requires a calibrated broadband sensor, the particles strike a well-characterized metal plate, at a known velocity, and the burst acoustic emission signals must be separated in time by 1 ms. In process analysis, it is unlikely that all (or any) of these requirements can be met. 

In contrast to a quartz microbalance, the requisite IDT components are deposited only on one side of the crystal. These take the form of planar, interleaved, metal electrode structures, (with permission from Plenum Publishing, New York) where adjacent electrodes are supplied with equal but opposite potentials (Fig. 47). Application of a time-varying r. f. potential causes the crystal to undergo physical deformations, and if these are confined to the surface region of the crystal, the result is a surface acoustic wave (Fig. 47 B) [248]. Such vibrations will interfere constructively only if the distance L H between two adjacent fingers" (see Fig. 37 A) is equal to one-half the elastic... 

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