異なるマトリックス樹脂を用いた一方向炭素繊維強化複合材料の高温非主軸疲労挙動

概要

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Off-axis fatigue behavior of unidirectional continuous carbon fiber-reinforced composites has been studied for T800H/epoxy. AS4/PEEK, and T800H/Polyimide systems, with a particular emphasis on the effect of matrix and matrix/interface properties at elevated temperature. Tensiontension fatigue tests were performed at 100℃ for various kinds of plain coupon specimens with different fiber orientation angles. It was observed for these composite systems that the fatigue strengths decreased with increasing off-axis angles. Regarding the epoxy- and PEEK-based laminae, almost linear off-axis S-N relationships were obtained over the whole range of fatigue loading up to 10^6 cycles. The off-axis fatigue strength of the polyimide-based laminae significantly dropped near the fatigue cycle of 10^4 which was ascribed to the initial defect of non-uniform fiber distribution. Normalizing the fatigue stress with the static strength at test temperature, the off-axis fatigue data eventually fell on a single S-N relationship for these composites. This characteristic was described well by a non-dimensional effective stress defined on the basis of the classical static failure theories. It was also demonstrated that the off-axis fatigue behavior of these unidirectional fiber composites was described by the classical composite fatigue failure models.
1999-04-25