Effect of Fiber Reinforcement on Dynamic Crack Growth in Brittle Matrix Composites

Abstract

An experimental investigation is conducted to study the interaction of a running crack with embedded fibers. Dynamic photoelasticity is used to evaluate the crack velocity and the instantaneous stress intensity factor, KID, as the crack propagates across the fibers. Fractography is used to explain the interaction of the dynamic crack front with the fiber. The results show that fibers significantly reduce the stress intensity factor and also the crack velocity. The effect of a weak fiber-matrix interface on crack velocity and KID is studied. A weak interface reduces KID but has no effect on the crack velocity. The crack closing forces applied by fibers bridging the crack faces have been determined for both the strong and weak interfaces and their effect on KID is explained.