INTERLAMINAR AND INTRALAMINAR FRACTURE MODES IN 0-90 CROSS-PLY GLASS EPOXY LAMINATE

Delamination of a cross-ply 0/90 glass fibre-reinforced composite lami nate with an epoxy-phenol matrix was studied using a double cantilever beam test. Fracture toughness was determined by measurement of bend a ngle of the cantilever beams. Results obtained with this method were i n agreement with those from conventional compliance and area methods. Two different fracture modes were observed: interlaminar and intralami nar. In the interlaminar fracture mode, crack jumps in the space betwe en two neighbouring 0-degree and 90-degrees plies were observed. With the interlaminar fracture mode, during crack initiation G(IC) decrease d with crack length. Intralaminar fracture mode consisted of the gradu al growth of a crack through a 0-degree ply. Fibres bridging the oppos ite sides of the crack were observed in this case, and fracture toughn ess G(Ic) did not change with crack length. G(Ic) (420 J m-2) at intra laminar fracture mode was approximately twice that at interlaminar fra cture mode (220 J m-2). The difference in fracture toughness was expla ined by the dissipation of energy by fibres bridging the opposite side s of the crack at intralaminar fracture mode.