AN EXPERIMENTAL AND ANALYTICAL STUDY OF DELAMINATION OF UNIDIRECTIONAL SPECIMENS WITH CUT CENTRAL PLIES

The effect of various factors on delamination has been studied using unidirectional glass fibre and carbon fibre-epoxy specimens with cut central plies. It is concluded that the fracture energy is not a material constant. Among the various factors which affect the fracture energy, the specimen thickness and the through thickness normal stress are the two most significant ones. A simple model is proposed to take account of these two factors. The new model gives excellent correlation with experimental results and is able to account for the effect of through thickness compressive stresses in mode II fracture, which is ignored in conventional fracture mechanics calculations.