Estimation of Fatigue Crack Initiation Life of Notched Specimen under Bending or Torsional Loading

It was shown in the previous papers by the present authors that the fatigue crack initiation life of a notched specimen under axial load can be estimated from the Kσ-Kε relationship and σ-ε relationship of the material. In this paper, an attempt was made to apply this method to the case under bending or torsional loading by modifying the nominal stress of a notched specimen under axial loading. Fatigue tests were carried out under plane bending, and the results obtained coincided approximately with the estimated fatigue lives. In the case of rotating bending and torsional loading, the estimated fatigue lives were compared with the fatigue test data by other investigators and were found approximately to agree with them.