Bending Fatigue Life Prediction Model of Carburized Gear Based on Microcosmic Fatigue Failure Mechanism

Bending fatigue tests of carburized gear in high cycle fatigue life regime were performed under stress ratio of 0.04. All the crack sources of the broken teeth are originated from the stress concentration on the surface of teeth root. By considering the effects of surface residual stress, notch effect, stress gradient and crack size, the predicted initiation life model of carburized gear is established by dislocation energy method. Meanwhile, based on the Paris Equation, the crack length a corresponding to fracture toughness and real crack propagation path, the predicted growth life model of carburized gear can be established. Finally, based on the behaviors of crack initiation and propagation, the whole life prediction model of carburized gear can be constructed, and the prediction accuracy of the model is within three times of the test life, which can be used to predict the bending fatigue life of carburized gear.