真空微重力环境纹理表面粘着-碰撞滑动接触摩擦机理研究

Under the environments of vacuum and microgravity, high friction between contact surfaces will severely influence the stability and lifetime of spacecraft, and how to reduce friction forces between contact surfaces is one of the most critical problems. Adhesion effects in vacuum environment and collision effects in microgravity environment make the contact body stay at adhesion-collision contact status. In this project, adhesion-collision sliding contact problems of textured surfaces under the environments of vacuum and microgravity will be investigated. Based on two scientific issues including adhesion-collision kinematic mechanism of sliding contact body and friction mechanism of textured surface during adhesion-collision sliding contact, the movement characteristics of the adhesion-collision sliding contact body, modelling method of adhesion-collision sliding contacts, influences of parameters of textured surfaces and contact body on the friction characteristics, and design method of textured surfaces will be studied under the environments of vacuum and microgravity. Through numerical simulations and experimental studies, a modeling method of adhesion-collision sliding contact problems under vacuum and microgravity will be developed. Adhesion-collision kinematic mechanism of sliding contact body under these environments will be summarized, and friction mechanism of adhesion-collision sliding contacts of textured surfaces under vacuum and microgravity will be proposed. Finally, a method which is used to design textured surfaces with lower friction characteristics will be developed, and better textured surfaces which can reduce friction effectively will be obtained. The results of this project will contribute to improving the friction characteristics of contact components under the environments of vacuum and microgravity, and the lifetime of spacecraft will be enhanced further.

真空微重力环境接触界面的高摩擦严重威胁着航天器的运行稳定性和使用寿命，如何降低航天器运动部件的摩擦力已成为亟待解决的关键问题之一。真空环境粘着效应与微重力环境无规则碰撞使真空微重力环境接触体处于粘着-碰撞接触状态。本项目以真空微重力环境纹理表面粘着-碰撞滑动接触问题为对象，围绕真空微重力环境滑动接触体粘着-碰撞运动机制及纹理表面粘着-碰撞滑动接触摩擦机理等科学问题，开展该环境粘着-碰撞滑动接触体运动特征、粘着-碰撞滑动接触问题建模方法、纹理表面参数与接触体参数对摩擦性能的影响规律以及纹理表面设计方法等内容的研究，通过数值模拟和实验测试，发展适用于该环境粘着-碰撞滑动接触问题的建模方法，阐明真空微重力环境滑动接触体粘着-碰撞运动机制和纹理表面粘着-碰撞滑动接触摩擦机理，建立改善摩擦性能的纹理表面设计方法，获得有效降低摩擦力的纹理表面，为改善航天器运动部件摩擦性能、延长使用寿命提供理论指导。

航天器工作在真空微重力环境中。真空环境使运动部件表面处于原子清洁状态，金属表面间原子键结合造成摩擦的粘着分量显著增大，摩擦过程演变为“粘着-剪切-粘着”的交替作用过程；微重力环境下，接触体受到很小的载荷扰动后，就会沿载荷扰动方向产生运动分量，进而与接触边界发生碰撞，摩擦过程表现为碰撞接触与驱动运动的耦合作用过程。真空微重力环境综合作用下，接触界面的高摩擦严重威胁着航天器的运行稳定性和使用寿命，如何降低航天器运动部件的摩擦力已成为亟待解决的关键问题之一。本项目以真空微重力环境纹理表面粘着-碰撞滑动接触问题为对象，研究了粘着-碰撞滑动接触体的运动特征，提出了粘着-碰撞滑动接触问题建模方法，基于粘着-碰撞滑动接触模型，研究了纹理表面参数与接触体参数对摩擦性能的影响规律以及纹理表面设计方法，通过数值模拟和试验测试，阐明了真空微重力环境滑动接触体粘着-碰撞运动机制以及纹理表面粘着-碰撞滑动接触摩擦机理。研究结果表明，对于软金属润滑，粘着-碰撞滑动接触过程中，碰撞动能转化为基体的变形能和热能，碰撞作用导致接触体压入深度增加、接触面积增大，与微重力悬浮滑动接触相比摩擦力增大，碰撞对摩擦的影响不可忽略；纹理表面都能够在不同程度上降低摩擦力，随纹理深度的增大，摩擦力先减小后增大，而摩擦力随纹理宽度的增大而增大；对于不同形状的纹理表面，矩形纹理能够得到更优的摩擦性能；纹理方向对摩擦力有较大影响，纹理方向为45°时其平均摩擦力约为0°时的2.4倍；摩擦力随接触体的尺寸增大而增大，随接触体滑动速度增大，摩擦力先近似线性增大，当滑动速度增大到一定程度后，摩擦力不再随速度发生变化。此外，对于软金属与二硫化钼结合的润滑，其摩擦性能与二硫化钼层的褶皱效应密切相关。本项目的研究成果，将有助于进一步完善空间摩擦学理论，为航天器运动部件降低摩擦力，实现长寿命稳定运行奠定理论基础，同时为空间摩擦学设计提供新思路。