炭素繊維複合材料の疲労特性に及ぼす繊維方向の影響

抄録

The fatigue limit and crack growth behavior of slit specimens of epoxy base carbon composites were investigated. The fatigue limit was defined by maximum stress amplitude that the specimen endured 10⁶ times stress repeating. Also, that was calculated by net stress at ligament. Carbon fiber directions were parallel and perpendicular to the load axis. The highest value of fatigue limit was obtained when all fiber directions were parallel to the load axis. However, crack grew along the fiber direction or load axis in the case of long slit. In the cases of two carbon directions that is, parallel and perpendicular to the load axis, the fatigue limits were evaluated from the result of the specimen that all carbon directions were parallel to the load axis. When measured value of fatigue limit was higher than the evaluated value, it was expected that the strain constraint occurred due to resistance of fiber in perpendicular to the load axis. When the measured value was lower, the peeling of fiber from epoxy was expected to be occurred. According to those results, it was expected that fatigue limit of smooth specimen of carbon composites with long fiber can be evaluated from the results of slit specimens