Contents I. Introduction
Crankshaft is one of the most important moving parts in internal combustion engine [1]. The strength of the crankshaft affects the reliability and life of internal combustion engine largely. Crankshaft bearing the gas pressure inside the cylinder, reciprocating and rotating inertia force of cyclical changes in the quality of the load which has been forced to crankshaft when engine working, at the same time torsional vibration, bending vibration and axial vibration have also been forced to crankshaft. So the bending stress and torsional stress in crankshaft will produce and lead to the bending deformation and torsional deformation. The stress concentration has been produced in the transition rounded corners of crankshaft. And now with the strength of engine enhancing, the working conditions of crankshaft become more and more harsh. The measures to ensure the crankshaft working reliability are essential.