某柴油发动机主轴承盖螺栓的动力学性能分析

主轴承盖螺栓作为发动机中重要的紧固零件,因工作中承受着复杂的动态激励载荷容易发生疲劳失效。在考虑装配预紧力、曲柄连杆惯性力和气体作用力的情况下,采用有限元方法建立了主轴承盖螺栓联接结构动态分析力学模型,分析了主轴承盖螺栓在复杂激励载荷下的应力分布特点,探讨了装配预紧力、曲柄连杆惯性力和气体作用力等重要工作参数对螺栓螺纹牙根部和最大应力截面中心区域应力分布的影响。结果表明,气体作用力是主轴承盖螺栓重要的外部冲击载荷;主轴承盖螺栓最大应力截面中心区域等效应力随着预紧力的增加而增大;工况(转速)对主轴承盖螺栓的受力影响不显著;螺纹牙根部最大应力区域径向等效应力在螺纹牙根部附近急剧下降,其后至螺纹中心逐渐减小。研究对主轴承盖螺栓可靠性和疲劳寿命设计具有一定的理论参考价值。

Dynamics Performance of the Main Bearing Cap Bolt in a Diesel Engine

Because of working under complex and dynamic load, the main bearing cap bolts that important fasteners in the engine are prone to fatigue failure. Based on considering the preload force, the inertia force of the crank link and the gas force, the dynamic analysis model of the coupling structure of the main bearing cap bolts is established by using the finite element method. The stress of the main bearing cap bolt under complex excitation load is analyzed. The influence of important working parameters such as assembly preload, crank link inertia force and gas force on the stress distribution of the root of the bolt thread and the central area of the maximum stress section are discussed. The results show that the gas force is an important external impact load of the main bearing cap bolts. The equivalent stress of the central section of the main bearing cap bolts increases with the increase of the preload force. The influence of the working condition (speed) on the force of the main bearing cap bolts is not significant. The radial equivalent stress of the maximum stress region of the root of the thread decreases sharply in the vicinity of the root of the thread, and then gradually decreases to the central area of the thread. The results can provide certain theoretical reference for reliability and fatigue life of bearing cap bolt design.