Weak interface in long fiber composites

The problem of the diffusion of load from a fiber to an embedding matrix is considered in a three dimensional context. It is assumed that the fiber-matrix interface allows sliding, which is assumed to be proportional to the interface tangential stress. The close-form solution is obtained for generic loads applied to the fiber, and the case of a concentrated force is studied in detail. The main effects of the interface stiffness, such as avoiding the stress singularities and increasing the length of the zone of influence, are discussed and illustrated by some numerical examples. Successively, the problem of the broken fiber is considered and solved with the same method as the previous case. Three different situations are discussed: no interaction between fibers, very close neighboring fibers and an intermediate case. It is shown that both problems have the same equations apart from a given function which plays the role of the constitutive equation and which characterizes the considered model. The effect of the neighboring fibers on the interfacial stress is discussed and it is shown that it has a non-monotonic dependence on the distance between the fibers. (C) 2000 Elsevier Science Ltd. All rights reserved.