EFFECTS OF RELATIVE SLIDING DISTANCE ON THE FRICTIONAL STRESS TRANSFER IN FIBER-REINFORCED CERAMICS

The effect of surface roughness on the shear frictional sliding resist ance of fiber-reinforced ceramics, especially in the small fiber-matri x relative sliding region, has been studied using the single fiber pus h-out and push-back tests. SiC (SCS-6) fiber-reinforced glass matrix c omposite was used as a model system. The load-displacement relationshi ps obtained for the 'seating drop' region in the push-back test, which corresponds to a completely sliding interface, were analyzed as a fun ction of fiber-matrix relative displacement, u, at the pushing surface . Result showed that the interface shear sliding stress, tau(s)(u), of a fully debonded interface in the small region of u below the mean ha lf wavelength of the large nodules on the fiber surface, could be writ ten as: tau(s)(u) = tau(0) + tau(s)(R)(u) where tau(0) is the intrinsi c shear sliding stress and tau(s)(R)(u) shows the u-dependence of shea r sliding stress and is related to the fiber surface roughness. This f unctional relationship between the interface sliding stress and displa cement, especially for small u, is very important for crack bridging a nalysis of fiber-reinforced ceramics. (C) 1998 Elsevier Science S.A. A ll rights reserved.