基于形貌多尺度表征的齿面润滑、热、弹耦合接触机理研究

Coupled thermo-elasto-lubricated status can be found as the gear tooth surfaces engage. The contact behaviors can be complicated as the micro-topography of the tooth surfaces play a role. Misunderstanding of the tooth contact behaviors leads to the ambiguity of tooth surface failure mechanisms, which further restricts the development of the modern gear design method. The involute spur gears are studied to propose a methodology able to clarify the thero-elasto-lubricated coupling effects and the multi-scale effects of tooth surfaces on gear contact behaviors by using a numerical contact model of tooth surfaces with multi-scale characterizations. The technical route is as follows: Tooth surface topography is measured with a high-resolution digital microscope, which is mathematically treated with the wavelet transform to separate its frequency components and to realize reconstruction of tooth surfaces without a specific frequency component. The parameters of the gear geometry, motion, load, and the lubricant properties are calculated to form a complete thermo-elasto-lubricated contact model for a spur gear pair. The variations of the contact pressure, the film thickness, the surface deformation, the temperature, the tooth friction are predicted within a whole meshing period to evaluate the contact performance. Effects of the lubricant properties, thermal environments, and the working conditions on contact behaviors are studied to understand the thero-elasto-lubricated coupling effects. Through the multi-scale decomposition of the tooth surface based on the wavelet transform, effects of scale of surface topography on contact performance of the gear pair are studied.

齿面啮合时工作在热、弹、流耦合状态，在齿面微观形貌作用下，接触行为十分复杂。对齿面接触研究的不够深入导致齿面失效机理不明确，制约了现代齿轮设计的发展。本项目以渐开线直齿轮为研究对象，提出计及齿面多尺度特性的齿面接触数值方法，阐明齿面啮合过程热、弹、流耦合机制及齿面尺度效应对接触性态的影响规律，突破以往齿面接触研究中物理场单一及齿面形貌尺度效应不明确的局限。具体内容包括：采用显微系统测量齿面微观形貌，提出小波变换算法实现齿面形貌的多频率成分分离与重构，计算齿轮几何、运动、载荷与润滑液本构、密度、粘度参数，构建温度场、压力场、膜厚场数值迭代方案，得到完整啮合周期压力、膜厚、变形、温度、摩擦的变动，评价齿面接触性态，研究润滑介质、热环境、工况对齿面接触行为的影响规律，揭示齿面啮合时热弹流耦合机制，通过研究抽离特定尺度成分后重构的齿面形貌接触性态，阐明齿面形貌多尺度特性与齿面接触行为的关联作用。

对齿面润滑接触机理的研究不够深入，导致齿轮传动成为现代机械装备的薄弱环节，制约了高端装备如风电、直升机等的发展。开展齿面接触研究应综合考虑啮合齿面间的润滑、温度、微观形貌等影响，真实描述齿面宏微观接触状态，为齿面疲劳与失效研究奠定基础。项目以多尺度、多物理场的观点进行齿轮副接触使役过程模拟，以齿面间压力、温度、摩擦、变形等评价齿面接触性能，为探明齿面失效机理奠定基础，具有重要的理论意义与工程价值。.1）.采用数码显微系统对不同齿廓形貌进行测量，实现界面间隙/膜厚方程中的表面形貌项的确定性表征；根据齿轮啮合原理推导齿间滑滚速度、齿面载荷、接触曲率半径等，确定齿轮油剪切力-剪应变率本构方程、粘度-压力-温度方程、密度-压力-温度方程等物理化学属性，构建由系统几何运动方程组、系统平衡方程组、系统本构方程组、系统连续性与集成方程等构成的润滑、热、弹耦合界面接触数值模型。.2）.通过压力场、膜厚场与温度场迭代求解方案实现了润滑、热、弹多物理场耦合，其中压力场采用双极子混合迭代法，温度场采用能量方程直接求解法，齿面变形采用DC-FFT法计算，混合润滑状态采用统一雷诺方程模拟，得到完整啮合周期内齿面压力、膜厚、变形、温度场、摩擦力的波动，评价啮合过程中齿面接触性态。研究了润滑介质物理特性、轮齿热环境及工况对齿面接触行为的影响规律，揭示润滑、热、应力场之间的耦合作用。.3）.推导出涂层齿轮接触弹性变形及应力场频响函数，开发基于DC-FFT的高效算法，解决涂层齿轮的啮合受力问题，揭示涂层力学与热属性对轮齿啮合状态的影响规律，为涂层齿轮与功能梯度材料工程设计开发提供理论指导。.对比研究计划按期完成了研究任务，解决了在多物理场耦合齿面接触大规模数值模型中体现形貌尺度效应和多场耦合粗糙齿面接触大规模数值求解两个关键科学问题，并开拓了非均质梯度材料齿轮润滑接触数值研究方法与表面硬化齿轮上的应用，为指导重载齿轮摩擦学与接触性能设计制造提供支撑。