二冲程航空活塞发动机连杆可靠性分析

李义

长沙强盛动力有限公司企业技术中心，湖南 长沙  410199

摘要：为研究某二冲程航空活塞发动机连杆在循环载荷作用下的可靠性寿命，利用有限元软建立连杆组分析模型，合理设置连杆组件内部零件之间的接触类型；基于连杆装配工况、最大压缩工况和最大拉伸工况进行应力分布计算；采用材料应力-寿命曲线与Gerber平均应力修正模型对连杆进行高周疲劳特性评价，得到连杆在不同载荷下的安全系数，并对装配该连杆的发动机整机进行150 h耐久试验。应力及高周疲劳计算结果表明：连杆在3种工况下的静强度均符合设计要求，接触应力能保证内部零件之间的连接可靠；在由3种典型工况组成的一个工作循环内，连杆最小疲劳安全系数为1.33，疲劳安全系数满足设计要求。耐久试验后拆机检查结果表明：零件无裂纹，摩擦表面的磨损、光亮、划痕等缺陷均符合评价标准，连杆关键尺寸与形位公差均符合设计要求。

关键词：有限元法；航空活塞发动机；罚函数法；等效应力；疲劳分析

Reliability analysis of connecting rod in two-stroke aviation piston engine

LI Yi

Research and Development Center, Changsha Qiangsheng Power Co., Ltd., Changsha 410199, China

Abstract: To study the reliability life of a two-stroke aviation piston engine connecting rod under cyclic loading, a connecting rod group analysis model is established using finite element software. The contact types between the internal parts of the connecting rod assembly are reasonably set, and stress distribution calculations are carried out based on the connecting rod assembly condition, maximum compression condition, and maximum tension condition. The material S-N curve method and Gerber average stress correction model are used to evaluate the high cycle fatigue characteristics of the connecting rod, and the safety factor of the connecting rod under different loads is obtained. A 150 h durability test is conducted on the entire engine equipped with the connecting rod. The stress and high cycle fatigue calculation results show that the static strength of the connecting rod under three working conditions meets the design requirements, and the contact stress can ensure reliable connection between internal parts. In a working cycle consisting of three typical operating conditions, the minimum fatigue safety factor of the connecting rod is 1.33, and the fatigue safety factor meets the design requirements. After the durability test, the dismantling inspection results show that there are no cracks in the parts, and the wear, gloss, scratches and other defects on the friction surface meet the evaluation standards, the key dimensions and positional tolerances of the connecting rod also meet the design requirements.

Keywords: finite element method; aviation piston engine; penalty function method; equivalent stress; fatigue analysis