Interlaminar and intralaminar fracture surface morphology in graphite/epoxy laminates

Fracture surface morphological studies of graphite/epoxy (T300/934) laminates have been performed to distinguish between mode I and mode II interlaminar and intralaminar fractures. Additionally, the effect of a few hygrothermal conditions on mode I fracture surface is also assessed. Centre notched tension, compact tension, double cantilever beam and cracked lap shear specimens have been used to study these fracture modes. While mode I fracture is characterized by branched cracks between fibers, river pattern and chevron markings on resin rich zones, the epoxy hackles dominate mode II fracture surface. The interlaminar and intralaminar fractures can be distinguished by fiber spacings and some matrix features. The effect of increase in temperature and/or moisture is seen to cause reduction in matrix microcracking and increase in fiber pullout in mode I.