EFFECTS OF THE FIBER CONTENT ON THE LONGITUDINAL TENSILE FRACTURE-BEHAVIOR OF UNIDIRECTIONAL CARBON EPOXY COMPOSITES/

This study is concerned with the effects of the fiber content on the m acroscopic and macroscopic fracture mode of unidirectional carbon/epox y composite. Necked-on-thickness specimens having a fiber volume fract ion (V-f) ranging from 30 to 70% were tested in tension in the fiber d irection. The effects of the fiber volume fraction on the fracture app earance were then examined. The results show that a transition in frac ture mode occurred, from tensile fracture at the necked region at low V-f to interlaminar shear failure at high V-f. Fracture-mode transitio n also occurs at the microscopic level. Examination of SEM photomicrog raph of the specimen surface shows that, at low V-f the specimen fract ured in fiber-break dominated fracture, whilst, at high V-f interfacia l-damage dominated fracture was observed. An analysis to determine the conditions for the occurrence of each fracture mode is presented. (C) 1997 Elsevier Science S.A.