Characteristics of Delamination Growth in a Notched Graphite/Epoxy Composite Laminate

This paper presents the results of an investigation to determine the delamination states which develop in a quasi-isotropic [(± 45) 2 /O 2 /90 2 ] s graphite/epoxy laminate with a circu lar hole due to tension-tension loads. The tests were performed at different constant-load amplitudes, and specimens were nondestructively inspected for damage and locations of delamination using a diiodomethane (DIM) enhanced X-ray radiography. Mechanisms of delamination growth were discussed and stiffness reductions due to damage were mea sured. A model for predicting the initiation and locations of delamination along curved edges was presented. Comparison of observed initial delamination locations with pre dicted results shows a good agreement between them.