基于裂纹萌生-扩展演变行为的齿面微观形貌与疲劳磨损关联建模

Fatigue wear is a common failure mode for gear. Although different micro topographies on tooth surface lead to great differences in fatigue wear performance, their quantitative relationship and the corresponding physical process, are not clear. To this end, the quantitative relationship and its mechanism between surface topography and fatigue wear of tooth for spur gearing, are investigated based on crack initiation and propagation evolution behavior. The main contents include: (1) Taking the random characteristics of surface topography into consideration, the variation rules and statistical modeling of gear contact stress field are studied based on random process theory, with mixed elastohydrodynamic lubrication model and elasto-plastic contact mechanics of rough surfaces. The association models between surface topography and crack initiation and propagation evolution behavior, are then established using fatigue-damage accumulation theory and fracture mechanics. (2) Based on the evolution behavior of crack initiation and propagation, the evolution law of surface topography is researched. The variation rules and characterization of topography features are studied, through revealing the correlation among micro topography characterization parameters in wear process. (3) Based on the evolution behavior of crack initiation and propagation, the relations, between the mean, the extreme and the spatial attributes of micro topography and the overall and the local wear distributions, are researched. The quantitative mapping relations are established between the characterization parameters of micro topography and fatigue wear. The research provides a theoretical basis for the anti fatigue wear design of gear surface topography.

疲劳磨损是齿轮常见失效形式，不同齿面微观形貌导致疲劳磨损性能相差较大，两者定量关系及其物理作用过程尚不明晰。为此，项目针对直齿圆柱齿轮传动，基于裂纹萌生-扩展演变行为研究齿面微观形貌与疲劳磨损定量关联及其机制，具体包括：（1）考虑齿面微观形貌随机性，借助混合弹流润滑和粗糙曲面弹塑性接触模型，基于随机过程理论研究齿轮接触应力场变化规律及其统计建模方法，再由累积损伤和断裂力学方法建立微观形貌与裂纹萌生-扩展演变行为关联模型；（2）基于裂纹萌生-扩展演变行为研究齿面微观形貌磨损演化规律，通过揭示磨损过程中微观形貌各表征参数之间相关性，研究微观形貌结构特征变化规律及其参数表征方法；（3）基于裂纹萌生-扩展演变行为研究微观形貌均值、极值和空间结构特征与齿面整体、局部疲劳磨损分布关联，建立微观形貌与疲劳磨损表征参数之间定量映射关系。项目实施为齿面微观形貌抗疲劳磨损设计提供一定理论依据。

粗糙齿面接触作用下的裂纹萌生扩展行为形成齿轮疲劳磨损，对齿轮传动精度和服役寿命产生较大危害。研究齿面微观形貌与齿轮接触应力、裂纹萌生扩展的关联对深入认识齿轮疲劳磨损失效机理、促进齿面微观形貌设计有重要作用。. 项目将齿轮啮合等效为粗糙曲面接触，基于随机过程和统计理论研究了齿面微观形貌及接触微凸体的建模方法，基于仿真样本研究了微观形貌表征参数之间相关性，结合粗糙曲面弹性接触理论和ZMC模型研究了粗糙曲面弹塑性接触模型，基于体积守恒准则研究了考虑材料塑性流动的弹塑性接触计算方法，开展了接触压力随机分布统计建模方法研究，研究了齿面微观形貌统计分布参数对接触应力的影响，基于累积损伤理论和线弹性断裂力学研究了裂纹萌生和扩展行为，基于实测齿面和微凸体弹塑性接触模型研究了齿轮接触应力场与疲劳寿命随粗糙度变化规律，基于相关性分析手段研究了微观形貌表征参数与接触应力关联，由逐步回归和通径分析方法构建了齿面粗糙度参数与接触应力关联模型。. 项目研究发现：1）相较于现有模型，所提微凸体建模方法与实际轮廓均方误差更小，误差降低了24%-69%；2）独立表征微观形貌的粗糙度参数集为Ra、RSm、Rsk和Rku；3）不考虑塑性变形所产生的粗糙齿面接触预测偏差，与塑性指数、粗糙度有关；4）接触斑数、接触斑宽度、接触斑间距和平均接触压力是决定接触应力的主要参数，其中亚表层接触应力大小取决于p*b/Sp，亚表层最大接触应力深度取决于n*Sp；5）齿面微观形貌标准偏差对裂纹萌生与扩展有较大影响，这种影响与啮合曲率半径有关，相关长度作用不显著；6）粗糙度值Ra小于0.3μm时，粗糙齿面和光滑齿面接触疲劳寿命差别较小，粗糙度值Ra为0.5μm-0.9μm时，接触疲劳失效发生在近表层，齿轮接触疲劳寿命随微凸体密度、微凸体平均曲率半径减小而降低，微凸体曲率半径比微凸体密度对接触疲劳寿命影响更大；7）粗糙度参数对最大Mises应力综合影响大小依次为Sa>Smr1>Sp>Spk>K，对最大剪应力综合影响大小依次为Sa>Spk>Vmp。

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