基于动力学和摩擦学分析的曲轴疲劳强度分析  

Study on Fatigue Strength of Crankshaft-Bearing System of Engine Crankshaft based on Dynamic and Tribological Analysis

作　　者：何芝仙[1] 桂长林[2] 李震[1] 孙军[2] 

机构地区：[1]安徽工程科技学院机械工程系,安徽芜湖241000 [2]合肥工业大学机械与汽车学院,安徽合肥230009

出　　处：《内燃机学报》2008年第5期470-475,共6页Transactions of Csice

基　　金：国家自然科学基金资助项目(50175023)

摘　　要：以某4缸柴油机曲轴为研究对象,根据曲轴的承载特点,提出了基于曲轴—轴承系统动力学和摩擦学分析的曲轴动应力计算方法,即在曲轴有限元分析时通过在曲轴轴颈表面动态施加包含曲轴—轴承系统动力学和摩擦学特性的动态油膜压力计算曲轴动应力,最后把损伤积累理论应用于曲轴疲劳强度计算。计算结果表明:动应力在曲轴轴颈表面的分布主要取决于油膜力对其弯曲和扭转作用以及应力集中效应,动应力随时间的变化与内燃机的发火次序密切相关。与传统方法相比,由损伤积累理论计算的曲轴安全系数下降了5.34%。A novel method to calculate the dynamic stress on the surface of a crankshaft based on the dynamic and tribological behavior of the crankshaft-bearing system is presented for a four cylinder internal combustion engine. In the finite element analysis, by exerting the dynamic pressures of oil film on the surface of the crankshaft, the dynamic stress on the surface of crankshaft journal is calculated. The accumulative damage theory is applied in the calculation of the crankshaft fatigue strength. Numerical results show that the dynamic stress distribution on the crankshaft journals is mainly determined by bending, torsion and stress concentration of the crankshaft as oil film loads are applied. The dynamic stress variation with time is closely related to the firing sequence of engine. The safety coefficient of crankshaft decreases by 5.34% by the accumulative damage themy compared with the traditional method.

关 键 词：曲轴-轴承系统 动态油膜压力 动应力 损伤积累理论 雨流计数法 

分 类 号：TK402[动力工程及工程热物理—动力机械及工程]