Analyses of fiber push-out tests performed on Nicalon/SiC composites with tailored interfaces

The interfacial properties of Nicalon fiber-reinforced SiC composites with tailored (i.e. weak or strong) interfaces are characterized using single-fiber push-out tests. A simple analysis is proposed to include the surface roughness of the fiber in the push-out model. Specifically, the roughness effect is characterized by the difference between the fiber push-out stress and the fiber reseating stress, which is obtained from fiber push-back tests. A method is developed to analyze the loading stress vs fiber-end displacement relation (i.e. the push-out curve) during the push-out process to evaluate the interfacial properties. The push-out curve for composites with weak fiber bonding can readily be analyzed by the existing push-out model incorporated with the roughness effect. However, premature catastrophic debonding at the interface is required to interpret the push-out curves for composites with strong fiber bonding.