二つ以上の錐孔を有する鋼試験片の回転曲げ疲労について

抄録

We carried on the rotating bending fatigue test of steel specimens with two holes and over. Specimens tested have radial holes drilled under the different conditions reciprocally, in parts of A and B types. Every specimen of A type has each hole axis on the same longitudinal section. Every specimen of B type has each hole axis on the same cross section. We investigated the effects that the conditions of drilled holes and the interference of mutual holes had on the fatigue strength. The results obtained are as follow;
(1) In A type, the fatigue limits are raised slowly with the increase of the number of holes up to six holes in each pitch of holes 2mm, because of stress relaxation caused by the interference of mutual holes.
(2) In the hole pitches of 2mm and of 6mm, the fatigue limit for 2mm is higher than that for a single hole, but the fatigue limit for 6mm comes almost to the same value as that for a single hole. In the pitch of 6mm, the stress relaxation is not caused by the mutual holes.
(3) In B type, the fatigue limits are reduced with the increase of maximum stress caused at holes under repeated load. In the same value of maximum stress, the time strengths by overstress are reduced with the increase of the number of holes.
(4) In comparison of the mechanical properties of various specimens subjected to repeated load and those of each virgin specimens, we obtained the effects of conditions of drilled holes upon the degree of fatigue progress.