脉冲爆震轴向载荷对双半内圈球轴承疲劳寿命的影响

针对脉冲爆震涡轮发动机(PDTE)中的周期性、强非定常轴向载荷可能导致滚珠轴承可靠性降低的问题,应用损伤力学理论和有限元法建立了PDTE中双半内圈球轴承的疲劳寿命预测模型,研究了在脉冲爆震燃烧室(PDC)引入的周期性、强非定常轴向载荷作用下双半内圈球轴承的疲劳寿命。研究结果表明双半内圈球轴承的两个半内圈均在接触区次表面最大切应力位置处萌生裂纹,随后裂纹逐渐扩展至表面导致轴承疲劳失效。在PDC爆震阶段,由于引起第一半内圈疲劳损伤的切应力范围较小,因此第一半内圈的疲劳寿命较高；而在PDC填充和排放阶段,由于接触摩擦作用以及滚珠滚过第二半内圈时产生较大的切应力范围,从而导致第二半内圈的疲劳寿命较低。在对PDC爆震阶段引入的峰值轴向载荷进行合理设计后,PDTE中双半内圈球轴承的疲劳寿命主要由第二半内圈的接触状态和轴承的润滑条件决定。本文的研究成果为PDTE中滚珠轴承的选型与设计提供参考。

Effects of Pulse Detonation Axial Load on Fatigue Life of Split Inner Ring Ball Bearing

To solve the problem that periodic and strong unsteady axial load in pulse detonation turbine engine (PDTE) may reduce the reliability of ball bearing, a fatigue life prediction model of split inner ring ball bearing in PDTE was established by using damage mechanics theory and finite element method. The fatigue life of the split inner ring ball bearing under periodic and strong unsteady axial load introduced by pulse detonation combustor (PDC) was studied. The results show that two half inner rings initiate cracks at the position of the maximum shear stress on the subsurface of the contact zone and then the crack gradually spreads to the surface, which leads to the fatigue failure of the bearing. In PDC detonation process, the fatigue life of the first half inner ring is higher because the shear stress range that causes fatigue damage is smaller. In the fill and purge process, the fatigue life of the second half inner ring is lower due to contact friction effect and larger shear stress range caused by the balls roll through the second half inner ring. After the reasonable design of the peak value of axial load introduced in the detonation process of PDC, the fatigue life of the split inner ring ball bearing in PDTE is mainly determined by the contact state of the second half inner ring and the lubrication condition of the bearing. The study results of this paper provide a reference for selection and design of the ball bearing in PDTE.