界面粗糙度对摩擦行为的影响机理研究

From a microscopic point of view, surface can't be perfectly flat, thus the friction behavior is highly dependent on the roughness of interface, each scale of roughness shows a different tribological feature. The real contact area between two rough surfaces is the sum of the areas of contact between facing asperities. Since the real contact area is a fraction of the nominal contact area, the real contact pressure is much higher than the nominal contact pressure, which results in plastic deformation of asperities. As plasticity is size dependent at size scales below tens of micrometers, with the general trend of smaller being harder. In this project, we aim to study the effect of micro-scale roughness on frictional behavior of interface. Firstly, we would study the non-local plasticity behavior of single asperity-asperity contact model at micro-scale, and further investigate the plasticity effect/size effect on the interfacial friction behavior. In addition, we would investigate the interaction of asperity deformation (elastic and plastic) effect on multi-asperity contact, and effect would be verified by using large scale finite element simulation on rough surface contact/friction. And finally, an electro-mechanical system based sensor device is proposed to measure stress/strain fields at the interface in static/steady contact/sliding. Robust deviations of interfacial parameter evolution between the experiments and the theoretical model would be briefly discussed. The project aims to understand the connection of multi-scale plastic response, results from this study can be used as theoretical foundation for new surface-interface design.

从根本上讲，没有绝对光滑的界面，摩擦性能与界面粗糙度相关，不同尺度的粗糙度展示了不同的摩擦性能特点。摩擦副的真实接触面积，在微观上表现为若干个微接触对的面积总和，真实接触面积值往往要远小于投影接触面积。为此，接触斑上的接触应力要远大于整体接触平均应力，导致塑性变形的产生。在微米尺度的塑性行为中，接触塑性行为体现出了尺度效应，表现为越小越硬的特点。在本项目中，申请者拟研究微米尺度粗糙度对材料界面摩擦性能的影响，首先研究微米尺度下的非局部塑性行为，理解材料塑性以及相关的尺度效应对单个微米尺度接斑的影响。并在此基础上，研究表面接触斑之间的相互作用，结合大规模计算模拟粗糙表面的摩擦性能。最后，通过设计合理的界面摩擦实验，验证理论模型／计算中得到的界面接触信息的演化规律。项目拟通过研究，加深理解摩擦过程中各个尺度下接触弹塑性响应的相互关系，期望对设计摩擦学界面起到定量的指导作用。

针对粗糙表面的接触与滑动问题，建立了离散接触对的跨尺度摩擦模型。利用该模型，首先研究了了微尺度塑性行为对单接触对滑动、以及粗糙表面滑动的影响研究；建立了考虑塑性损伤的表面微观磨损模型，模型考虑了表面形貌的统计分布以及三体摩擦磨损效应，揭示了表面粗糙度、滑移速度等对宏观摩擦性能的影响；建立了考虑结构变形与振动能量耗散的宏观接触模型，探讨有限厚度、有限刚度对接触力历史和能量耗散的影响规律。更进一步，开展跨尺度接触摩擦力学的工程应用研究，建立了全尺寸快堆堆芯接触肿胀计算模型，发展了堆芯组件的弹塑性跌落模型，为核燃料组件的可靠性评估提供理论支撑。