繊維配向角がＣＦＲＰ積層板のモードＩおよびモードＩＩ層間破壊靭性に及ぼす影響

Abstract

The objective of this study was to investigate the effect of fiber orientation on Mode I and Mode II interlaminar fracture toughness of CFRP laminates by conducting DCB (Double Cantilever Beam) tests and ENF (End Notched Flexure) tests. In Mode I loading, Mode I interlaminar fracture toughness at initiation, GIC, became higher as the fiber orientation inclined to the crack propagating direction. Mode I interlaminar fracture toughness during propagation, GIR, were almost constant macroscopically in two cases of the delamination at [0/0] interlamina of unidirectional specimen and the [(0/90)/(0/90)] interlamina of plain weave specimen. The delamination at [0/0] interlamina showed a stable fracture behavior. However, the delamination at [(0/90)/(0/90)] interlamina showed a cross-linked stable-unstable fracture behavior. Contrary to it, GIR increased immediately as the crack propagated and as the fiber orientation inclined to the crack propagating direction. In Mode II loading, Mode II interlaminar fracture toughness at initiation, GIIC, became lower, on the contrary to the case of Mode I, as the fiber orientation inclined to the crack propagating direction. Mode II interlaminar fracture toughness during propagation, GIIR, increased immediately as the crack propagated, nothing to do with the fiber orientation, and as the fiber orientation inclined to the crack propagating direction. The fracture surface observation by SEM was also added.