微点蚀齿轮法向接触刚度分形预估模型

Fractal Prediction Model of Normal Contact Stiffness of Micro-pitting Gear

微点蚀作为齿面疲劳点蚀失效作用的初期特征,准确地预估其法向接触刚度是研究齿轮系统动力学故障特性重要课题之一。结合微观尺度下表面形貌分形参数和接触点面积分布作用,通过单微凸体弹-塑性接触力学性能研究引申建立结合面法向接触刚度分形模型,定性地分析微观元素对法向载荷和法向接触刚度的影响。根据渐开线齿轮宏观几何尺寸和微观微点蚀物理几何成因,建立近似粗糙度模拟微点蚀特征的预估分形参数,研究齿面不同加工工艺和不同程度微点蚀特征的渐开线齿轮法向接触刚度特性。结果表明:表面微观元素对法向载荷和法向接触刚度具有不同的影响作用,且元素之间具有关联性,沿齿廓啮合点具有不同的表面接触系数,提高齿面精度(降低粗糙度)能够提高啮合齿面法向接触刚度。齿面微点蚀使得齿轮结合面法向接触刚度明显降低,仿真结果与实际工程相吻合,为后期分析微点蚀动力学响应及微点蚀扩展等做研究基础铺垫。

Micro-pitting is the initial failure feature of tooth surface with fatigue pitting. Estimating its normal contact stiffness is one important subject to study the dynamic fault characteristics of gear system. Combined the fractal parameters of surface morphology and the distribution area of contact points on the microscopic scale, the fractal model of joint surface with normal contact stiffness was established by studied the elastic-plastic contact mechanical properties of micro-convex, and the effect of microscopic elements on normal load and normal contact stiffness was analyzed qualitatively. The estimated fractal parameters for micro-pitting characteristic was established with the macroscopic physical dimension of involute gear and microscopic physical cause of micro-pitting, to studied normal contact stiffness of involute gear under different machining technology of tooth surface and different levels of micro-pitting. The result shows that the surface microscopic elements have different effects on normal load ang normal contact stiffness, and the elements have a certain relevance. The different surface contact coefficients are along the meshing point of the tooth profile, and improving the accuracy of the tooth surface(reducing the roughness) can improve the normal contact stiffness of the meshing tooth surface. The normal contact stiffness of joint surface of gear is lower significantly with the micro-pitting of tooth surface, and the simulation results are consistent with the actual engineering. The proposed mathematical model of micro-pitting can be used as a basis for analysis of dynamic response and expansion of micro-pitting.