Enhanced mode-II fracture toughness of an epoxy resin due to shear banding

摘要

The Brazilian disk specimen is used to measure the fracture toughness of an epoxy resin material under model-I and mode-II loading conditions. It is found that even though the apparent fracture behavior seems to be brittle for both loading modes, the mode-II fracture toughness is more than three times higher than the mode-I fracture toughness. Such a substantial increase in fracture toughness under mode-II load- ing contradicts are prediction of the maximum hoop stress criterion, which has been validated for most brittle fractures.