The propagation of cracks in composites consisting of ductile wires in a brittle matrix

Two types of fracture toughness specimens, double cantilever beam and single-edge notch, were constructed from nickel wires in an epoxy resin matrix. The critical stress intensity factor to cause propagation of an unbridged matrix crack arrested at a wire was found to be greater than that for plain resin. Subsequent crack propagation could be described by taking account of the stress intensity factor due to known forces in the crack-bridging wires which subtracted from that due to the applied forces. The debonding and pull-out behaviour observed previously in single-wire specimens was confirmed in the multi-wire fracture toughness specimens.