Analysis on Rolling Contact Fatigue Evolution with Consideration to the Distortion Effect Induced by Normal Stress

Rolling contact fatigue of M50 steel is investigated with consideration to the elasto-plastic behavior of materials. The multiaxial stress model is used for evaluating the influence of both the normal stress difference and shear stress on the fatigue evolution. The effect of material distortion induced by the normal stress difference is specifically analyzed during the initiation and propagation processes of spalling. Changes in the multiaxial stress on different surfaces, as well as their effect on the fatigue evolution are discussed. The results show that in addition to the shear stress, the normal stress difference has significant effect on fatigue evolution as well. Especially on certain rough surfaces, the stress concentration in near-surface layers generates obvious difference among the normal stresses in the orthogonal direction. The corresponding material distortion energy due to the increasing elastic strain accelerates the crack initiation in near-surface layers, which consequently reduces the rolling contact fatigue lifetime.