The interaction of elastic waves with fluid-loaded structures have been extensively investigated by numerous authors. In most applications, because of its better acoustical properties (attenuation and acoustic impedance) as compared to air, fluid is usually introduced to aid in the process of ultrasonic inspection of solid components. The fact that a great deal of information about the constituents of the fluid-loaded structure can be extracted from acoustic measurements was the driving force behind many of the studies conducted on such configurations. For a long time the fluid coupling was believed to have a minor effect on the behavior of the loaded structure. Although this assumption still holds for most fluid-loading situations, there exist some instances in which the fluid plays a major role in the wave propagation process.; This research effort is directed towards the investigation of the effects of fluid-loading on the behavior of elastic waves propagating in selected fluid-loaded configurations. We detail some of the anomalies associated with fluid-loading in three different cases of interest, namely, (a) circumferential creeping waves around a fluid-filled cylindrical cavity in an infinite elastic medium, (b) investigation of the opposite effect of fluid-loading on the velocity of dilatational waves in thin plates and rods, and (c) investigation of the low-frequency oscillation of a fluid layer between two elastic plates. The results of these investigations revealed some of the fascinating aspects of elastic wave propagation in fluid-loaded solid elastic structures, and certainly confirmed that fluid-loading may play a major role in determining the propagation characteristics of elastic waves in fluid-loaded structures.
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