本文运用线弹性断裂力学理论研究了290型柴油机的稀土球墨铸铁曲轴的断裂强度和寿命问题.曲轴断裂的主要原因在于曲柄臂与连杆轴颈过渡圆角处存在缺陷.这个位置的缺陷(裂纹或类裂纹)在疲劳扩展达到临界状态时便导致曲轴失稳断裂.本文还根据断裂力学的理论和实验分析,提出了降低断裂率的一些途径. In this paper, the rupture strength and life of rare earth nodular cast iron crankshafts of 290 diesel engine are studied by the theory of linear elastic fracture mechanics.The main reason of the crankshaft rupture is the defect in the transition fillet of crankshaft and connecting rod journal.The defects Or type of crack) leads to the instability of the crankshaft when the fatigue propagation reaches a critical state.This paper also puts forward some ways to reduce the fracture rate according to the theoretical and experimental analysis of fracture mechanics.