Ultrasonic Non-Destructive Testing of Materials.
Interim rept. no. 2, 1 Aug 78-31 Jul 80,
CORNELL UNIV ITHACA NY DEPT OF THEORETICAL AND APPLIED MECHANICS
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This report describes broadband measurements of ultrasonic dispersion and attenuation in cross-plied specimens of graphite-epoxy. Quantitative comparisons of dispersion and attenuation data are made by means of least-square fit algorithms implemented into the ultrasonic signal processing system. Reproducible measurements in graphite-epoxy have been obtained. Two new frequency-dependent attenuation measurement techniques are described for measurements in composite materials. One is a continuous-wave resonance technique and the other is based on the Kramers-Kronig relation to find the attenuation from measurement of the dispersion. The new techniques are expected to be especially useful for measurements in highly absorbent composite specimens. A firm basis for the technique has been established and measurements with graphite-epoxy specimens are described. Good agreement can be obtained between the various attenuation measurement techniques. Author
- Laminates and Composite Materials