扭动微动磨损损伤力学机理研究

Torsional fretting is defined as a relative motion of small amplitude induced by reciprocating torsion under alternating load. It usually occurs in many rotary components under alternating torsion load . Wear caused by torsional fretting can lead to problems about mechanical components service safety and human health. At present, the operation and damage mechanism of torsional fretting wear has been established by the systemically experimental study. But the mechanical mechanism of torsional fretting damage is necessary to be investigated. In this study, an numerical analysis model which can reasonably describe the friction damage behavior on the torsional fretting surface will be established to investigate the effect of different fretting parameters and material properties on contact stress and strain distribution. The displacement and stress fields dominated equation of sphere-plane contact, which is loading monotone incremental torque, will be derived, and the distribution and evolution rule of the normal stress and tangential stress will be researched. Torsional fretting wear experiment will be carried out for two representative aluminium alloy materials, then the Running Condition Fretting Maps will be established and damage law will be summarized base on the scar analyses. With mechanical parameters of torsional fretting damage being ascertained, mechanical mechanism of torsional fretting wear and the competition between local fatigue and wear will be revealed by the contact mechanics theoretical research, the numerical simulation and the experiment validation. This research not only has a great scientific significance to deepen the torsional fretting damage mechanism, but also offers important engineering guidance for the problem of the high speed train axles fracture.

扭动微动磨损是指交变载荷下接触副接触界面发生微幅扭动的相对运动，通常发生在承受交变扭矩载荷的回转部件中。其产生的损伤会引发机械零部件服役安全及人体生命健康问题。目前的试验研究建立了扭动微动磨损的运行和损伤机理，但缺乏对其损伤力学机理的认识。本研究将建立能合理描述扭动微动表面摩擦损伤行为的数值分析模型，考察不同微动参数和材料性质对接触应力分布的影响；推导单调递增扭矩作用下球—平面接触位移场和应力场的控制方程，研究法向应力和切向应力的分布及演化规律；同时开展两种典型铝合金扭动微动磨损试验，建立其运行工况微动图，结合微观分析，总结损伤规律；通过接触力学理论研究、数值模拟和实验验证的综合分析，确定控制扭动微动损伤的力学参量，揭示扭动微动磨损损伤的力学机理和局部磨损与疲劳竞争机制的力学机理。本研究不仅对深化微动损伤理论有重要科学意义，也为高速列车车轴冷切断裂问题的解决提供了工程指导。

本研究对不同材料配副开展了扭动微动磨损实验研究，通过运动动力学曲线分析﹑磨斑形貌演变分析﹑二维轮廓分析和磨损机制分析，对比了材料性质对扭动微动磨损性能的影响。同时，基于理论分析和有限元方法，通过用户子程序嵌入摩擦生热模型，建立扭动微动热力耦合有限元分析模型开展摩擦热作用下的微动接触力学行为研究，研究了材料性质对扭动微动接触表面及次表面的应力应变分布以及温度的影响，研究了不同扭动微动运行区域下温升、应力应变的分布和随微动循环的变化。基于Green函数推导接触问题的位移和单位应力关系解析解，即推导相应的影响系数，建立了基于半解析法（SAM）的数值分析模型，并通过离散卷积-快速傅立叶变换（DC-FFT）技术和共轭梯度法（CGM）来加快求解和收敛速度；通过修正Archard方程﹑引入变摩擦系数模型，考虑更加符合实际的表面摩擦和表面几何演化；利用此模型，对铝合金-GCr15钢摩擦副的扭动微动磨损行为进行了预测，考查了粗糙表面的接触压力和黏滑状态，同时研究在不同法向力和切向力情况下，最大应力出现位置以及界面微滑情况。通过接触力学理论研究、数值模拟和实验验证的综合分析，确定控制扭动微动损伤的力学参量，揭示扭动微动热力耦合效应和磨损损伤力学本质规律。此外，本项目还建立了三维热弹性涂层板滑动接触模型，利用伽利略变换和傅里叶变换，求得了位移场、应力场、温度场在傅里叶域下的解，利用共轭梯度法和快速傅里叶变换求得了涂层压头与涂层板之间的热流分配。此部分工作为进一步研究热弹性涂层板在扭转载荷作用下的扭动微动接触问题奠定了基础。. 综上所述本研究揭示了扭动微动损伤的力学本质规律，同时为建立局部磨损与疲劳竞争机制形成的力学机理奠定了基础，为深入认识扭动微动损伤力学机理﹑提出防护措施提供了重要支撑。