Measurements of Scattering of Ultrasound by Ellipsoidal Cavities,
ROCKWELL INTERNATIONAL THOUSAND OAKS CA SCIENCE CENTER
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Experimental results have been compared with theory for ellipsoidal and spherical cavities embedded in titanium alloy by the diffusion bonding process. The measurements comprised the cases of incident longitudinal and shear waves including mode conversion. Whenever possible, comparisons were performed with the results of exact theory and those of the Born approximation. The Born approximation was found useful in the back scattering directions for low ka values k is the wave vector of the sound wave and a is the radius of the scatterer. In the experiments, a fundamental reciprocity relation was discovered which should prove very useful in further studies. The relation shows that the same angular dependence is obtained in mode conversion when the mode of the incident and scattered wave is interchanged. This result has now been corroborated by both the exact theory and the Born approximation.