航空活塞发动机机体疲劳优化设计方法

Fatigue Optimization Design Method for Block of Aero Piston Engine

机体可靠性差是航空活塞发动机适航取证过程中的技术难题。以某型发动机下机体为研究对象,通过模型仿真得到机体的瞬态载荷曲线并进行拟合,按实际安装对其进行约束,采用Goodman方法进行高周疲劳分析,计算机体疲劳安全系数;提出一种分离式主轴盖的设计方法,优化下机体结构,在相同载荷的条件进行对比分析;采用威布尔数学模型对机体可靠性指标进行计算验证,并对优化后的机体进行耐久测试。结果表明:下机体疲劳安全系数、整机寿命、可靠性大幅提升,该设计方法对提高类似结构可靠性有一定的借鉴意义。

Poor reliability of engine block is a technical problem in airworthiness certification of aviation piston engine.Taking the engine block of a certain type of engine as the research object,the transient load curve of the engine block is obtained and fitted through the model simulation,and it is restrained according to the actual installation.The Goodman method is used to analyze the high cycle fatigue of the engine block,the fatigue safety factor of block is obtained.A design method of separated main bearing cap is put forward to optimize the structure of the lower engine block,and the comparative analysis is carried out under the same load conditions.The Weibull mathematical model is used to verify the block reliability indexes,and the optimized block is performed with durability test.The results show that the fatigue safety factor,engine life and reliability of the lower block are improved,and the design method is of a certain reference value to improve the reliability of similar structures.