基于多体动力学的柴油机曲轴疲劳寿命分析

摘要

In order to analyze the fatigue life of 4100QBZL diesel engine crankshaft, the coupled multibody dynamics model of crankshaft system was established.The load simulation results of main journal and connecting rod journal under the flexible body model of crankshaft were acquired and the static strength was then checked.Finally, the crankshaft fatigue life prediction was conducted by combining the load spectrum collected from multibody dynamics software, the stress and strain finite element analysis results of the crankshaft under various conditions and the fitted SN curve according to the material properties.The results show that both the crankshaft static strength and fatigue life can meet the design requirements of the project.The life of critical position for crankshaft is beyond 1013 times, so it is thought that crankshaft fatigue failure will not happen.%为分析4100QBZL柴油机曲轴的疲劳寿命,建立该曲柄连杆机构的刚柔耦合多体动力学模型,将多组试验测量的缸内压力作为驱动力,进行耦合仿真得到曲轴在柔性体模型下的主轴颈、连杆轴颈负荷仿真结果,并根据载荷结果对曲轴进行静强度校核.最后结合由多体动力学软件得到的载荷谱与有限元分析所得的曲轴在各个工况下的应力应变分析结果,以及通过材料的各项属性拟合出的S-N曲线,对曲轴进行了疲劳寿命预测.结果表明:曲轴的静强度及疲劳寿命均达到了工程设计要求,曲轴最危险部位的寿命次数也达到了1013以上,认为曲轴不会发生疲劳破坏.