Effect of the Superimposed Stress of High Frequency on Fatigue Strength

Abstract

The fatigue property of low carbon steel under the composite stress which was made by superposing the ordinary rotating bending stress and the vibrating stress of higher frequency was examined in this study. The experimental results were discussed by focusing on the effect of the ratios of the magnitudes and the frequencies of component stresses. It was ascertained that in some ranges of these parameters the fatigue life under the composite stress could be estimated by the criterion that the composite stress was equivalently replaced by the stress of constant amplitude whose magnitude was the sum of those of the component stresses. For the values of the parameters outside the ranges, the criterion did not hold and the fatigue life was reduced appreciably from the value given by the criterion. Another method for estimating the fatigue life by calculation was also presented, which was available for the latter case.