A Modified DCB Specimen for Mode I Testing of Multidirectional Laminates

Abstract

A detailed study of the Mode I interlaminar fracture toughness measure ment of multidirectional laminates is presented. The use of a novel DCB specimen is pro posed in which the conventional DCB specimen is delaminated along its edges by the in corporation of inserts in addition to the usual delamination at the loaded end. Investigations using this specimen to examine the fracture toughness at +45°/+45° and +45°/-45° interfaces indicate that the appropriate width of edge delamination can sup press the crack jumping and fibre bridging which occur in the conventional DCB speci men. Preliminary tests show that G IC for +45°/+45° and +45°/-45° interfaces in multidirectional laminates are significantly higher than the G Ic measured for a 0°/0° inter face in a unidirectional laminate.