Macroscopic and Microscopic Elastic Constant Measurements of Ceramic Matrix Composites Using Ultrasonic Waves

Abstract

This paper presents the results of elastic constant determination of Ceramic Matrix Composites (CMC) using two types of ultrasonic measurement systems, and shows the possibility of the elastic constants determination for transversely isotropic materials not only in a macroscopic area but also in a microscopic one at the order of 1 mm. Macroscopic elastic constants were determined from the transmitted wave velocities measured by a double-through-transmission method. Microscopic elastic constants were inverted from the reflection coefficients at a small spot on the surface, which were measured using an ultrasonic micro-spectrometer. The inversion from the reflection coefficients was tried by two ways of analysis: (1) fitting to phase curves of reflection coefficients; (2) fitting to surface wave velocity dispersion. By comparison between these values and those measured by tensile tests, it was conformed that all elastic constants of a unidirectional CMC could be determined by ultrasonic waves appropriately not only in a macroscopic area but also in a microscopic one.