渐开线直齿轮弹流润滑下的接触疲劳寿命分析

CONTACT FATIGUE LIFE ANALYSIS OF INVOLUTE SPUR GEAR UNDER ELASTOHYDRODYNAMIC LUBRICATION

以渐开线直齿圆柱齿轮为研究对象,建立了等温润滑条件下考虑冲击载荷、供油条件因素的渐开线直齿轮接触疲劳寿命模型,模型由润滑接触分析数学模型和有限元显式分析模型组成。润滑模型利用多重网格法以及多重网格积分法分别对油膜压力及油膜厚度进行求解后利用数值求解结果进行显式分析。利用显式分析得到von Mises等效应力分布,根据Smith-Watson-Topper接触疲劳计算模型,对轮齿的接触疲劳寿命进行模拟预测。结果表明,随着重合度的增加,沿齿廓的因冲击导致的疲劳危险区有向节圆对应节点处靠近的趋势,同时疲劳寿命也逐渐增大,说明重合度的增大可以有效控制齿面冲击进而提升轮齿的接触疲劳寿命。相比充分供油状态,乏油状态下的齿面摩擦使齿面接触疲劳寿命降低,同时疲劳危险区明显由次表面向表面靠近,增加了接触疲劳失效的可能性,说明弹流润滑对防止接触疲劳发生的重要性,同时也为更加合理地进行齿面处理提供了理论依据。

Under the condition of isothermal lubrication taking a involute spur gear as research object, a involute spur gear contact-fatigue life model composed of the lubricated-contact analysis and the explicit analysis was established. The condition which jioned the factor of impact and oil supply was intruduced. Based on the method of multi-grid and multi-grid integration values of pressure and thickness of the film were obtained and substitute the values into explicit analysis. Mises equivalent stress distribution was obtained by explicit analysis and according to Smith-Watson-Topper contact fatigue calculation model, predicting the tooth-contact fatigue life. The result shows that with the increase of the degree of overlap, the danger zone alone the tooth profile closes to the node and the fatigue life also increases. The result also indicates that increasing the degree of overlap can effectively control the impact of the tooth surface contact fatigue life. Compared to full oil state, friction in the contact which lack oil led the fatigue life decreases and the danger zone tends to moved from the subsurface to the surface. The result not only shows the importance of the elastohydrodynamic lubrication in preventing the occurrence of contact fatigue, but also provided a theoretical basis for maching the tooth surface.