平面曲げ疲労強度に及ぼす平滑試験片の縁,断面形状の影響および平面曲げと回転曲げの疲労強度の関係について  [in Japanese] The Effect of Shape of Smooth Specimen on Plane Bending Fatigue Strength and the Relation between Plane and Rotating Bending Fatigue Strength  [in Japanese]

The effects of loading type, shape of cross section and finishing conditions of the edge of specimens on fatigue strength were investigated on two types of smooth specimens of low carbon steel, one stress-relieved in vacuum and the other treated with tufftriding. As for the effect of loading type, the difference between the rotating and the plane bending fatigue strengths was studied on the specimens with circular cross section and the relation between the in-plane and the out of plane bending fatigue strengths were examined using the specimens with rectangular cross section. The influences of the shape of cross section and the edge finishing of specimens on the in-plane bending fatigue strength were studied on the specimens having circular, semicircular cross section and three kinds of edge finishing radius, respectively. The results obtained were summarized as follows : (1) On the stress-relieved specimens, a curve of total strain range versus the number of cycles to failure can represent all the results of the in-plane bending test specimens with circular cross section and three kinds of edge finishing radius, of the in-plane and the out of plane bending tests on the specimen with rectangular cross section and of rotating and the plane bending tests on the specimen with circular cross section. (2) As for the material used for the tests, the edge finishing has no effect on the in-plane bending fatigue strength for the stress-relieved and the tufftrided specimens with rectangular cross section.