In situ determination of elastic stiffness constants of thick composites

We summarize in this paper some of the challenges of making ultrasonic measurements in thick composites and, in particular, in determining non-destructively the matrix of elastic constants of such materials. The procedure relies on the point-source/point-receiver measurement technique by which various wave modes are simultaneously generated over a broad angular spectrum in a test specimen. A procedure is described for analyzing the measured wavespeeds to determine the elastic symmetry of a composite test specimen and its matrix of elastic moduli.