某发动机活塞强度与疲劳分析

STRENGTH AND FATIGUE ANALYSIS OF AN ENGINE PISTON

建立包括活塞、连杆和缸套等构件的有限元模型,较真实地模拟了活塞在工作过程中的受力特征,对活塞等构件进行热机耦合分析,建立了考虑活塞与活塞销、活塞销与衬套、活塞裙部与缸套之间的油膜接触及压力计算模型。此外,发动机整机动力分析还为活塞强度分析提供不同曲柄角下的荷载及加速度信息。实际工程应用表明,该方法实用、可行,计算结果与实测一致,所建立的计算模型能准确反映活塞的真实工作状况,对活塞裙部压力、关键部位应力与疲劳可以进行定量评估,为发动机活塞的优化设计提供基础数据。

A finite element model including piston,connecting rod,cylinder liner etc.,has been established,which simulates the piston loading characteristics during its working process to the greatest extent. A coupled thermo mechanical analysis of the piston was presented in the paper. It creates an analytical and numerical model of the oil film and the contact pressure in the contact surfaces between piston and piston pin,piston pin and bush,piston skirt and cylinder liner. Moreover dynamic load and acceleration of the piston and con-rod are calculated at different crank angle using corresponding full engine dynamic model with a commercial software. Engineering application shows that the above analytical model is feasible and reliable,and the results agree with that of the corresponding experiment. The established analytical model can accurately reflect the real stress status of the piston pretty well during its working process. It is able to assess and evaluate the piston skirt pressure,stress and fatigue life of the concerned areas quantitatively. As a conclusion, it provides basic data for the optimization design of engine piston.