考虑间隙不确定性的花键概率疲劳寿命预测方法

Probabilistic Fatigue Life Prediction Method of Spline Considering Clearance Uncertainty

花键在机械传动领域占有不可替代的地位,其使用寿命直接影响着设备的可靠性。现有的花键疲劳寿命预测模型大多仅考虑外载荷和材料等参数的影响,忽视制造中所产生的加工误差。加工误差导致花键的各齿侧隙不同,使得分配到各齿上的力大小各异,受载大的齿产生的累计损伤更严重,降低花键的实际使用寿命。因此,为得到更准确的花键疲劳寿命,基于国标对花键各误差的要求,推导不同加工精度时的花键侧隙分布范围,考虑侧隙不确定性对花键啮合齿数和齿上载荷分配的影响,建立等效力学模型,得到啮合齿数不确定性时的花键疲劳寿命分布,并与按照传统方法计算的花键疲劳寿命进行了对比。案例结果表明,花键疲劳寿命的均值为10^(8)个载荷循环,花键在2×10^(7)~7×10^(8)个载荷循环内发生疲劳破坏的概率达到50%。提出的花键概率疲劳寿命预测方法能够进一步考虑间隙不确定性的影响,为花键的可靠性设计提供指导。

Splines play an irreplaceable role in mechanical transmission systems,and their life directly affects the reliability of equipment.Most of the existing spline fatigue life prediction models only consider the influence of parameters such as loads and material uncertainty,but ignore the machining errors generated in manufacturing.Machining errors lead to different clearances of the spline,making the force distributed to each tooth different.The damage to the tooth with a large load is more serious,which reduces the spline life.Therefore,to obtain a more accurate spline fatigue life,based on the requirements of the manual for the spline errors,the distribution range of the spline clearance at different machining accuracy is deduced.Then,the effect of the clearance uncertainty on the number of engaged teeth and uneven distribution of force is considered,an equivalent model of the force carried by each tooth is established.Finally,the fatigue life distribution of the spline is obtained,and compared with the spline fatigue life calculated by the traditional method.The case results show that the average spline fatigue life is 10^(8)load cycles,and the probability of fatigue failure in 2×10^(7)to 7×10^(8)load cycles reaches 50%.The proposed probabilistic fatigue life prediction method can further consider the impact of the clearance uncertainty and provide guidance for the reliability design of splines.