Effect of fiber orientation and moisture absorption on the interlaminar fracture toughness of CFRP laminates

摘要

This study has clarified the effects of fiber orientation and the moisture content on G(IC)/G(IR) (Mode I energy release rate at initiation/propagation) and G(IIC)/G(IIR) (Mode II energy release rate at initiation/propagation) in CFRP laminates. The interlaminar fracture toughnesses at the 0/0, 30/- 30, 60/- 60, 0/90, and the (0/90)/(0/90) plain weave interfaces were measured using the DCB (Double Cantilever Beam) test and the ENF (End Notched Flexure) test. For the 0/0 interface, the interlaminar fracture toughness under dry, 50% relative humidity equilibrium, and wet conditions were also measured. Fiber orientations at delaminated surfaces were found to affect the interlaminar fracture toughness at initiation (G(IC) and G(IIC)) slightly, and the interlaminar fracture toughness during propagation (G(IR) and G(IIR)) strongly. Also, the degree of moisture absorption affected G(IC) slightly, anf G(IR) strongly. In Mode II, G(IIC) was strongly affected by the degree of moisture absorption. Contrary to this, G(IIR) was not affected by moisture absorption. [References: 22]