Damage accumulation during the fatigue of an injection moulded glass/nylon composite

Abstract

Tension-tension fatigue tests at a range of peak stresses have been performed on a 50% by weight discontinuous glass fibre reinforced Nylon composite having a skin/core structure. A continual decrease in modulus with cycling is observed for composite specimens and specimens taken from the skin layer alone. During cycling of composite specimens damage accumulates in both the skin and core layers and both layers contribute to the measured modulus reduction. The major form of damage in the core is transverse cracks which are initiated predominately at the free edges and grow across the specimen width with cycling. Cracking patterns in the core are simulated by using a model based on the Paris crack growth law incorporating the strain energy release rate for crack growth in the core.