Nanoscale Reciprocating Sliding Contact Behaviors of an Isosceles Trapezoid Textured Surface in Space Environment

Abstract

Background: In space environment, microgravity and vacuum influence the mechanical behaviors of the devices. In microgravity environment, the mechanical components will vibrate with a small amplitude once there is a disturbance. The vibration can be seen as a reciprocating sliding contact with a small amplitude. In addition to the vibration, adhesion effects are predominant in vacuum, which will induce a high friction force. Objective: To reduce the friction force, textured surfaces are widely used in mechanical engineering on the earth, and nanoscale textures are also verified that they can be used to improve the frictional behaviors of components with the size of nanometers. Methods: In this paper, the adhesion effects are considered by using molecular dynamics (MD) simulation, and the microgravity induced vibration is simplified as a reciprocating sliding contact. Coupling MD simulation and the finite element method, a multiscale method is used to investigate the frictional properties of nanoscale reciprocating sliding contact between rigid multi-asperity tips and an isosceles trapezoid textured surface. Results: Average friction forces for the different tips are presented, and the friction processes are analyzed. A stable friction process is discovered for a specific case, and the average friction forces keep at two stable values corresponding to two sliding directions. Conclusion: Compared with the total average friction forces of a smooth surface, the textured surface can reduce the friction forces greatly. This work could contribute to the textured surface design to improve frictional properties in space environment.