2018 Volume 18 Issue 2 Pages 95-102
Delamination is a predominant failure mechanism in composite structures. In the present study, double cantilever beam (DCB) tests were performed to investigate the effects of temperature and fiber orientation on the Mode I interlaminar fracture toughness, GI, of carbon/epoxy composites, T800H/#3631. The values of GI for three kinds of laminates, [012//012], [22.5/-22.5/08/-22.5/22.5//-22.5/22.5/08/22.5/-22.5] and [45/-45/08/-45/45//-45/45/08/45/-45], with a pre-cracked interface, that is // in each laminate, were obtained at various temperatures, i.e., -100°C, 20°C and 150°C. Fracture surface observation was also carried out by a scanning electron microscope (SEM) and optical microscope. It is shown that GI is obviously affected by the temperature and fiber orientation. In the case of the specimen with delamination at 0//0, the fracture morphology changes as the delamination increases, but the value of fracture toughness for initiation GIC (GI at the crack initiation) is not so different from the one for propagation GIR (GI during the crack propagation), and the fracture toughness of the specimen with 0//0 interface is little affected by the temperature. However, GIR of the specimen with 22.5//-22.5 interface shows a remarkable temperature dependence at a large crack length region. In case of the specimen with 45//-45 interface, GIR is considerably affected by both failure mechanisms of crack jumping and fiber bridging, and the effect of temperature on GIR is less than the case of the specimen with 22.5//-22.5 interface.
