基于瞬态分析的柴油机活塞疲劳寿命预测

以某增压柴油机活塞为研究对象,建立了由曲柄连杆机构和缸套组成的装配体有限元模型,计算了活塞在热载荷、机械载荷和热-机耦合作用下的应力分布,在此基础上将计算得到的热-机耦合应力场作为疲劳载荷,采用名义应力法对活塞进行疲劳寿命计算。结果表明:活塞的短寿命区域出现在活塞销座内侧上部,最低循环次数为8.823×10~7次,折合1 470.5h。从计算结果看,活塞的结构较为合理,能满足柴油机的使用要求。

Prediction of Fatigue Life for Diesel Engine Piston Based on Transient Analysis

Taking the piston of turbocharged diesel engine as the research object ,the FEA model of crank and connecting rod mechanism and cylinder assembly was built and the stress distribution of piston was calculated under thermal load ,mechanical load and thermal and mechanical coupling load .Then the thermal and mechanical coupled stress field was used as fatigue load and the fatigue life of piston was computed according to nominal stress approach .The results show that the short life region was the upper part inside piston pin boss .In this area ,the minimum cycle is 8 .823 × 107 or around 1470 .5 h .Accordingly ,the structure of piston is reasonable and can meet the application requirements of diesel engine .