基于最差件等寿命曲线的桨轴高低周复合疲劳寿命分析

以Goodman曲线为基础,构造了考虑应力集中系数和疲劳极限强度分散系数影响的最差件等寿命曲线,然后基于最差件等寿命曲线建立了桨轴高低周复合疲劳寿命分析方法,用于预测桨轴的安全寿命,并给出了预测方法的适用范围为低周103～105次循环。采用此方法对两种载荷下的某型航空发动机桨轴进行了高低周复合疲劳寿命预测,并与试验结果进行了对比。结果表明:基于最差件等寿命曲线的桨轴高低周复合疲劳寿命分析方法成功预测一组安全寿命低于低周1 000次循环的载荷,且另一组载荷预测结果也与试验结果相吻合,预测方法是可行的。 

HCF/LCF complex fatigue analysis of propeller shaft based on the worst-case equilife curve

Based on Goodman curve, the worst-case equilife curve considering the influence of the stress concentration and the dispersion coefficient of fatigue strength was constructed firstly, and then the worst-case equilife curve was used to establish the high-cycle fatigue/low-cycle fatigue (HCF/LCF) complex fatigue analysis method of the propeller shaft, and this method was used to predict the safety life of propeller shaft, but the applicable range of the prediction method the low-cycle fatigue was between 103 and 105 cycles. Adopting this method, the HCF/LCF complex fatigue of an aero-engine propeller shaft under two kinds of loads was analyzed, and compared with the experiment. The result shows that it is feasible to predict the HCF/LCF complex fatigue of the propeller shaft using the method based on the worst-case equilifecurve; and it can successfully predict a kind of loads safety life lower than 1000 cycles of low-cycle fatigue, and another kind of loads prediction result fits well with the experimental one.