Study of Quenched Crankshaft High-Cycle Bending Fatigue Based on a Local Sub Model and the Theory of Multi-Axial Fatigue

Abstract

For critical steel engine parts, such as crankshafts, the fatigue strength under the critical working condition is usually improved by the electromagnetic induction quenching technique. In a previous study, the strengthening effect of this approach was always evaluated by a constant, which may result in some errors with the change of the technological parameters. In this paper, a type of steel crankshaft is selected to study the strengthening effect of this approach; first a local sub model composed of the crankpin is built to simulate the magnetic–thermal coupling process, then, the residual stress field is determined by simulating the whole course of fabrication. Finally, the prediction of the fatigue limit load is proposed based on the residual stress and the strength parameters of the material. The experimental verification shows that, when compared to the general means of modification models, the modified McDiarmid multi-axial fatigue model is more suitable to be applied to analyze the fatigue property of this quenched crankshaft due to the markedly higher accuracy. Based on this study, a new fatigue-limit load-prediction approach of this kind of crankshaft can be proposed for engineering applications.