基于灰色估计和多项式变异理论的附件传动系统在随机载荷作用下的疲劳寿命预测

Fatigue life prediction under random loading for accessory transmission system based on grey estimation and polynomial mutation theory

针对航空发动机附件传动系统在随机疲劳载荷作用下的寿命预测问题,提出了综合灰色估计和多项式变异理论的疲劳寿命预测方法。运用灰色模型和多项式变异理论,得到二维载荷谱及等幅疲劳中值曲面。以平行轴-齿轮传动结构为例,基于Miner疲劳累积损伤理论,危险点的疲劳中值寿命计算值约为1.35×10^7次。验证试验中采用等效应力状态的40Cr标准试件,工艺流程依据GB3077-82可满足航空传动轴强度要求。定时截尾寿命试验的样本容量是45,试验样本寿命的均值约为1.42×10^7次,结构疲劳中值寿命的试验值略高于计算值,证明该计算方法是可靠并偏于保守的,为提升附件传动系统疲劳寿命提供理论参考和数据基础。

Considering the problem of life prediction of aero-engine accessory drive system under random fatigue load,a method of fatigue life prediction based on grey estimation and polynomial variation theory was proposed.Based on the grey model and polynomial variation theory,two-dimensional load spectrum and equal amplitude fatigue median surface were obtained.Taking parallel shaft-gear transmission structure as an example,the fatigue median life of the risk point was about 1.35×10^7 using Miner fatigue cumulative damage theory.During the verifying test,standard 40 Cr-workpieces were under condition of equivalent stress state.The processing process could satisfy the strength standard for aero transmission shaft in conformance to GB3077-82.In life test with equal censored time,the number of samples was 45.Median life for samples was about 1.42×10^7.As the result,the calculated value of fatigue median life was slightly less than the test value.The proposed method is reliable and conservative for improving the fatigue life of accessory drive system.