Bending or Torsional Fatigue of Notched Specimen with a Small Hole at the Notch Root

抄録

The fatigue limit of a defective material provided with a notch by mechanical processing can be estimated from that of a specimen made of a non-defective material with a hole at the root of a notch given by mechanical processing. From our examination on the bending and torsional fatigue of an S35C notched specimen with a hole of 0.3 mm in diameter at the notch, root, the following results were obtained : 1) When the root radius of the notch is larger than that of the notch at the branch point, the fatigue limit is determined by the propagating conditions of the non-propagating crack at the edge of the small hole in the case of bending or torsion. 2) If the root radius of the notch is smaller than that of the notch at the branch point, the bending fatigue limit is scarcely influenced by the existence of a small hole, but the torsional fatigue limit is decreased in the range of 10-20 %. 3) The notch factor of a notched specimen with a small hole at the notch root is small in comparison with that of a notched specimen without a hole in the case of bending or torsion.