The role of in-phase and out-of-phase overloads on the torsional fatigue of normalized SAE-1045 steel

Several researchers have demonstrated that, under both uniaxial and in-phase biaxial loading, periodic overloads of yield stress level magnitude can be used to eliminate the effects of crack-face interference. In the current research a series of experiments using either axial or torsional overloads were conducted in order to determine their effects on the torsional fatigue of normalized SAE1045 steel tubes. It was determined that, in the high cycle regime, both types of overload had the same impact on fatigue life. The effect on the torsional high cycle fatigue of axial /torsional mean stress following an axial/torsional overload was found to be minimal for both the zero mean and peak strain cases examined. Lastly, the results of these experiments were compared with similar fatigue data for this material from both axle-shafts and in-phase overload tests. This larger data set was then used to evaluate various multiaxial parameters, and it was found that the Fatemi-Socie-Kurath parameter yielded the best data correlation.