车用发动机连杆载荷谱编制技术研究

Research on the Method of Fatigue Loading Spectrum of the Connecting Rod in Vehicle Engine

应用有限元分析和动力学仿真相结合的方法,以发动机曲柄连杆机构为研究对象,基于柔性多体动力学理论,建立了活塞、连杆、曲轴和飞轮的刚柔耦合动力学模型,得到了连杆应力云图与载荷时间历程。分别计算了车用发动机在典型任务剖面下的连杆应力,对连杆危险节点的应力时间历程进行了雨流计数,通过对载荷谱外推和叠加,得到了发动机连杆目标载荷谱,并根据载荷分级的方法编制了连杆疲劳试验谱,为制定连杆疲劳寿命试验规范提供了参考依据。

Based on flexible multi-body system dynamic theory,and combining the finite element analysis and dynamics simulation method,it founded the rigid-flexible coupling multi-body dynamic analysis model of the crank and connecting rod mechanism of diesel engine,which included the piston,link,crankshaft and flywheel,and calculated the stress cloud and load time histories of the connecting rod.The dynamic stresses histories of the connecting rod were calculated under all the mission profile,which were analyzed by rain-flow counting algorithm and the fatigue damnification of connecting rod were calculated.The target load spectrum was got through extrapolation and repetition.Then it weaved the loading spectrum based on the load classification method,which can be used to do the fatigue test for the connecting rod.