EFFECTS OF FIBER ROUGHNESS ON INTERFACE SLIDING IN COMPOSITES

The presence of asperities at the fiber-matrix interface is noted experimentally as a load rise during the initial stages of push-out and as a reseating load drop during push-back. These effects are modelled by considering the elastic deformation of asperities at the interface. During fiber sliding, the decorrelation of initially matching fiber and matrix geometries results in an asperity pressure at the interface. Fractal models of interface roughness are incorporated into an equation of fiber sliding that is found to accurately reproduce experimental observations. Additionally, an asperity wear mechanism must be introduced to explain the effects of fatigue, the variation of fiber reseating with sliding distance, and the rapid decay in sliding stress during pristine fiber push-out.