Nano-sized single-asperity friction behavior: Insight from molecular dynamics simulations

Friction phenomenon plays an essential role in contact pairs, from macroscale to nanoscale friction. Nano-sized friction behavior is different from macroscopic friction behavior due to discreteness of atoms. Taking alpha-Fe as paradigm material, single-asperity friction molecular dynamics (MD) simulations are conducted. The MD results show that the multi-slip phenomenon exists during the tangential loading process of nano-sized single asperity. Meanwhile, the macroscopic friction coefficient model is not suitable for nano-sized friction, while the macro-scopic Kogut-Etsion (KE) contact radius model can approximately describe nano-sized contact radius. Besides, the Mindlin model can hardly describe the initial tangential stiffness under large normal loadings due to the neglect of plastic deformation. Therefore, it is suggested to modify the macroscopic friction models by consid-ering the plastic deformation mechanism and asperity size effect to improve the full-scale description ability.

Automated summary

Friction plays a crucial role in contact pairs at different scales, but nano-sized friction behavior differs from macroscopic behavior. The study found that multi-slip phenomenon occurs during the tangential loading of a single nano-sized asperity, and existing macroscopic friction models need to be modified to accurately describe nano-sized friction. The plastic deformation mechanism and the size effect of asperities also need to be considered.