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. Specificall y, the roughness effect is characterized by the difference between the fiber push-out stress and the fiber reseating stress, which is obtain ed from fiber push-back tests. A method is developed to analyze the lo ading stress vs fiber-end displacement relation (i.e. the push-out cur ve) during the push-out process to evaluate the interfacial properties . The push-out curve for composites with weak fiber bonding can readil y be analyzed by the existing push-out model incorporated with the rou ghness effect. However, premature catastrophic debonding at the interf ace is required to interpret the push-out curves for composites with s trong fiber bonding.