Fatigue Strength Estimation under Irregular Variable Combined Axial and Share Stresses

Abstract

The Wang-Brown or Dong methods were incorporated into the multiaxial high cycle constant-amplitude fatigue life prediction method proposed by the authors in the previous papers, so as to predict multiaxial high cycle irregular variable amplitude fatigue life. Multiaxial high cycle fatigue tests were performed using SNCM439 steel for verification. The stress amplitude, mean stress, and principal stress direction change in the stress waveform of the tests. The fatigue lives predicted by the Wang-Brown method were about three times longer than the experimental values. By contrast, the Dong method predicted fatigue lives that were about one-third shorter than experiments. This is thought to be because the stress range of each path is calculated to be smaller by the Wang-Brown method and larger by the Dong method in the stress waveform converted into Euclidean coordinates.