抄録
Because of extremely large anisotropy of unidirectional carbon-fiber reinforced plastics, it is very difficult to obtain its ultimate tensile strength in the fiber direction by use of the usual specimen shapes which have been used. Accordingly, (1) the stress distributions in the orthotropic specimens with circular cutouts widthwise or thicknesswise were analysed by use of finite element method in order to discuss which shape was more feasible, (2) as the result of static and fatigue tensile tests with various kinds of specimen dimensions, it was found that the fracture behaviors reasonably coincided with the theoretical consideration, and (3) consequently, a specimen that has larger circular radius of curvature cut out in the thickness, larger reduction ratio from ends to central crosssections and longer ductile tabs attached to both fixing ends and other related procedures were proposed for a standard testing method of unidirectional carbon-fiber reinforced plastics.
