Fracture Mechanisms and AE of Single-Fiber Composite. Effect of Fiber Surface Treatment and Roughness.

Abstract

The fracture mechanisms and interfacial properties of single-fiber composites with different surface treatments of the fiber are examined by acoustic emission. The fracture surfaces are observed with a polarized microscope. As a result, it is confirmed that AE events are generated at every fiber breakage. It is found that the fracture mechanisms of SFC are different when the surface treatment of a fiber or a matrix resin is changed. A method to measure the mean fragment length and evaluate the interfacial shear strength of fiber/matrix is proposed using AE events which are almost equal to the number of fiber breakages. The difference in the interfacial shear strength due to the fiber surface treatment can also be identified by this method. From the observation of a fiber surface with SEM, it is also found that this difference in the interfacial shear strength depends upon the surface roughness of the fiber.