The fatigue strength of steels containing small holes under out-of-phase combined loading

A criterion is presented for the prediction of the fatigue strength of defect-containing specimens subjected to combined axial and torsional loading at an R of −1. The criterion is applicable to loading situations where there is an arbitrary phase difference between the axial and torsional loadings. In order to check on the validity of the criterion, fatigue tests were performed using specimens of annealed carbon steel as well as of heat-treated alloy steel. The specimens contained a surface hole, which was either 100 or 500 μm in diameter. Good agreement between predictions and experimental results was obtained for both in-phase and out-of-phase loadings.