INTERLAMINAR AND INTRALAMINAR FRACTURE-TOUGHNESS OF UNIAXIAL CONTINUOUS AND DISCONTINUOUS CARBON-FIBER EPOXY COMPOSITES

The interlaminar and intralaminar fracture roughness of a continuous c arbon fibre/epoxy composite and an aligned discontinuous carbon fibre (DISCO)/epoxy composite have been measured using the compact tension a nd double cantilever beam test geometries. The DISCO composite was fou nd to have a slightly greater misalignment of the fibres from the aver age fibre direction and this misalignment was found to increase both t he initiation fracture toughness and to a greater extent the propagati on fracture toughness. The increase in fracture toughness in the DISCO samples was due to fibres bridging the crack and this has been modell ed as if the bridging fibres provide an increase in compressive stress across the crack analogous to a craze at the crack tip. (C) 1997 Publ ished by Elsevier Science Limited.