ＣＦ／ＥＰＯＸＹ積層板のモードＩ層間破壊挙動に及ぼす繊維配向角の影響

Abstract

The mode I delamination resistance and delamination growth behavior of CF/EPOXY laminates were investigated. DCB (Double Cantilever Beam) test was employed to study the effect of fiber orientation on the mode I interlaminar fracture behavior. Investigated in this study were the delamination growth behavior at [0/0], [30/-30], [60/-60] and [0/90] interlaminae of fabricated laminates with unidirectional prepreg as well as that at [(0/90)/(0/90)] interlamina of fabricated laminate with plain weave prepreg. The delamination resistance was estimated with the mode I energy release rate, GI. The highest value of GIC, GI at crack initiation, was obtained at the [(0/90)/(0/90)] interlamina, and the lowest one was at the [0/0] interlamina. The delamination at [0/0] interlamina showed a stable fracture behavior. On the other hand, the delamination at [(0/90)/(0/90)] interlamina showed a crosslinked stable-unstable fracture behavior. The values of GIR, GI during crack propagation, were almost constant macroscopically in these two cases. Contrary to it, the delamination growth at [30/-30], [60/-60] and [0/90] interlaminae showed the R-curve characteristic. The values of GIC at these interlaminae had little difference. Especially the values of GIC at [30/-30] and [60/-60] interlaminae were almost equal to the value of GIC at [0/0] interlamina. However, the values of GIR at [30/-30], [60/-60] and [0/90] interlaminae had very big difference. GIR at [60/-60] interlamina, compared with GIR at [30/-30] interlamina, and GIR at [0/90] interlamina, compared with GIR at [60/-60] interlamina, got higher immediately as the crack propagation proceeded. The fracture surface observation by SEM was also conducted. Consequently the effect of fiber orientation on the mode I interlaminar fracture behavior was clarified.