Modelling of Unidirectional Reciprocating Sliding Contacts of Nanoscale Textured Surfaces Considering the Impact Effects in Microgravity Environment

In space environment, the adhesion effects can cause a high adhesion component of a friction force, and the impact effects caused by the microgravity can induce a high ploughing component, so the friction force is higher than the ground environment. Nanoscale textures affect the adhesion behaviors by reducing contact areas, and they also vary the shear strength of the interface, which are beneficial to the friction reduction. Considering the impact effects, the motion of a clearance joint is simplified as a unidirectional reciprocating sliding contact, and a multiscale model is employed to investigate the friction and wear characteristics between a rigid cylindrical tip and nanoscale textured surfaces. The effects of texture shapes on running-in stages, average friction forces and wear characteristics are investigated. The results show that the isosceles trapezoid textured surface (surface II) and the surface with right-angled trapezoid textures on the right side (surface III) can come to steady states for different sliding modes. Surface II presents the lowest total average friction force to show its potential to reduce friction forces. The worn atoms are the least for surface III, and surface III can be used to improve the wear behaviors. The impact effects make that the unidirectional reciprocating sliding contacts show higher total average friction forces than reciprocating sliding contacts. This work could contribute to designing textured surfaces, reducing friction and wear in unidirectional reciprocating sliding contacts under impact effects in microgravity environment, and help to prolong the life of components in the spacecraft.