In modern metal matrix and ceramic matrix composites fiber-matrix interphases are specially designed to improve the fracture toughness of a composite, and to prevent fiber-matrix chemical reaction. As the interphase transfers load from the fiber to the matrix, the state of the bond between the interphase and the surrounding materials (fiber or matrix) determines the overall mechanical performance of the composite. Ultrasonic scattering from such interphases carries important information on the fiber itself and its bonding with the surrounding matrix material, thus having potential for fiber-matrix interphase characterization. Much work has been done on the study of wave scattering from cylindrical objects embedded in elastic media since 1950, owing to the importance of the subject [1–6]. Recent studies address scattering from coated fibers in composites [7–12]
