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Abstract In recent years, the nanoscale friction of layered two-dimensional materials have attracted much attention in both scientific and industrial communities due to their potential applications in various areas. As a typical two-dimensional material, graphene exhibits excellent mechanical properties and may be used as a dry lubricant. Therefore, friction analysis of graphene is essential for its application in engineering fields and has substantially improved our fundamental understanding of nanotribology. Many new nanoscale friction phenomena, laws and mechanisms of graphene have been reported continuously. However, many key issues about the influence of the critical factors on graphene friction behavior remain unclear. For example, the relationship between both the friction force and out-of-plane deformation exhibits complex behavior, which is yet to be understood. In this study, the friction behavior of a graphene flake on a support graphene substrate is investigated, by using molecular dynamics simulations. Based on a “graphene-spring” model, an elastic substrate is constructed to examine the dependence of the friction force on the indentation depth. The present work focuses on the interlayer friction behavior in the incommensurate registry. In the simulations, the friction force at the different normal loads and support stiffnesses are obtained. The results show that the friction force could be closely related to the indentation depth for various load or stiffness conditions, indicating that the indentation depth could be used to modulate the nanoscale friction directly. Particularly, the influence of normal load and substrate stiffness on graphene friction which can be normalized by the indentation depth. The present research has great significance for better understanding the friction law of the surface elasticity of two-dimensional materials.
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Received: 24 September 2019
Published: 12 June 2020
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2020, Vol. 41 
