2022 Volume 48 Issue 1 Pages 10-21
Interlaminar fracture toughness in carbon fiber reinforced plastics has been studied primarily using unidirectional or symmetric laminates. However, even in quasi-isotropic laminates, delamination caused by an out-of-plane impact could result in asymmetric, partial laminates. Thus, evaluating the interlaminar fracture toughness in asymmetric laminates, particularly that of Mode II associated with impact resistance, is necessary. Asymmetric laminates result in coupling effects, which cause warpage or twisting due to the thermal shrinkage derived from the molding process. In this study, based on the reports of Verchery et al., we manipulated the stacking sequences to generate zero coupling stiffness. Subsequently, Mode II interlaminar fracture toughness was experimentally and analytically examined using laminates with zero or non-zero coupling components. The results demonstrated that Mode II interlaminar fracture toughness was slightly higher in the laminates with zero coupling components than in those with non-zero coupling components. In addition, the crack tip geometry was significantly influenced by the coupling effects.
