微凸体对直齿轮接触特性及疲劳寿命影响分析

齿轮在加载循环过程中,粗糙表面微凸体接触会在齿轮次表面形成应力集中,形成初始疲劳裂纹,降低齿轮使用寿命.为了进一步研究直齿轮表面微凸体曲率半径、高度对表面弹塑性接触特性的影响规律,利用Hertz接触理论和粗糙表面形貌的Greenwood-Williamson理论,建立了粗糙齿面单微凸体法向正接触模型、粗糙齿面弹塑性接触模型和不同粗糙度的粗糙界面接触有限元模型,并验证了模型的正确性.通过模型结果与有限元结果分析得,增大微凸体曲率半径会使接触应力有所降低,微凸体越高所受接触应力越大,且微凸体高度对接触应力的影响大于微凸体曲率半径造成影响.根据模型所得结果利用基于多轴疲劳机理的Smith-Watson-Topper方法预测了不同粗糙表面疲劳裂纹萌生所需的加载循环次数.研究结果进一步丰富了对粗糙表面接触疲劳机理的研究.

Analysis of the influence of asperities on the contact characteristics and fatigue life of spur gears

During the loading cycle of gears, The contact of the rough surface and the convex body will cause stress concentration on the gear subsurface, forming initial fatigue cracks, and reducing the service life of the gear. Therefore, in order to further study the influence of the radius of curvature and height of the spur gear surface on the elastoplastic contact characteristics of the surface, the Hertz contact theory and the Greenwood-Williamson theory of rough surface topography were used to establish the normal direction of the rough tooth surface. The positive contact model, the elastoplastic contact model of rough tooth surface and the finite element model of rough interface contact with different roughness have verified the correctness of the model. According to the analysis of the model results and the finite element results, increasing the curvature radius of the asperity will reduce the contact stress. The higher the asperity, the greater the contact stress, and the height of the asperity has a greater impact on the contact stress than the asperity The body curvature radius affects. According to the results of the model, the Smith-Watson-Topper method based on multiaxial fatigue mechanism is used to predict the number of loading cycles required for the initiation of fatigue cracks on different rough surfaces. The research results further enrich the research on the contact fatigue mechanism of rough surfaces.