抄録
The results of the alternating torsional fatigue tests on notched carbon steel specimens are reported in this paper. The forms of the specimen used were 1) round bars with a longitudinal semicircular groove and 2) the round bars with a circumferential U groove. Fatigue limits obtained are the maximum nominal stresses at which no crack develops over 107 stress repetitions. The results obtained by the experiments are shown in Table 3. From the results of the experiments it is concluded that the crack initiates when the repeated stresses at the distance ε0t from the root of notch exceed the fatigue limits of the materials and the value of ε0t are nearly constant and are of the same order of magnitude as of rotary bending tests.
