Ultrasonic Characterization of Highly Attenuative Fiber-Reinforced Composites

Different specimens of highly attenuative fiber-reinforced composites have been investigated ultrasonically. Conventional pulseecho techniques cannot be easily applied to characterize these materials. due to lack of multiple echoes. Using a transmission technique. we were able to map the relative attenuation in a reproducible fashion. In order to eliminate errors due to energy losses at the interfaces, we measured the attenuation with specimens in the shapes of wedges or steps. The mapping of attenuation provides a technique to predict non-destructively the periodicity (or lack of) of the weave, the heterogeneities of the fibers and, to a lesser degree, of the matrix, the misalignment of the fibers and other irregularities.