Progress in Ultrasonic Measurements Research in 1990: Transient Sources for Acoustic Emission Work
Annual rept. 1 Oct 1989-30 Sep 1990
NATIONAL INST OF STANDARDS AND TECHNOLOGY GAITHERSBURG MD
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Many techniques have been used by acoustic emission workers to produce rapid transient disturbances in elastic media. Techniques employing transient sources are necessary for characterizing many acoustic emission system components such as receiving transducers, transfer media, and other sources as well. Wave forms from seven types of sources were studied by performing experiments in which the source and a high fidelity receiver were mounted on opposite sides of an aluminum plate. Soundspeeds in the plate had been previously measured to provide information necessary for the calculation of the plate Greens function. In each experiment, a source was triggered and the ensuing output from the receiver was captured by a transient recorder. The force waveform of the source was calculated by convolving the inverse of the plate Greens function with the captured waveform.