Techniques are described for measurements of the radiation pattern of elastic waves scattered by a complex bulk defect. The problems addressed are sample preparation, system calibration, data acquisition, and data processing. The results are given in terms of two specific defects: a circular crack extending from a spherical void and a dual spherical void. The diameter of the crack and the separation between the two voids are approximately the same, i. e. , 1200 mu m. The results show well-defined features in the time-domain, the real and imaginary part of the Fourier spectrum and in the impulse response function which can readily be used to distinguish between these two types of defects.
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