Effects of relative sliding distance on the frictional stress transfer in fiber-reinforced ceramics

The effect of surface roughness on the shear frictional sliding resistance of fiber-reinforced ceramics, especially in the small fiber–matrix relative sliding region, has been studied using the single fiber push-out and push-back tests. SiC (SCS-6) fiber-reinforced glass matrix composite was used as a model system. The load–displacement relationships obtained for the ‘seating drop’ region in the push-back test, which corresponds to a completely sliding interface, were analyzed as a function of fiber–matrix relative displacement, u, at the pushing surface. Result showed that the interface shear sliding stress, τs(u), of a fully debonded interface in the small region of u below the mean half wavelength of the large nodules on the fiber surface, could be written as: τs(u)=τ0+τsR(u) where τ0 is the intrinsic shear sliding stress and τsR(u) shows the u-dependence of shear sliding stress and is related to the fiber surface roughness. This functional relationship between the interface sliding stress and displacement, especially for small u, is very important for crack bridging analysis of fiber-reinforced ceramics.