Study on the energy dissipation mechanism of atomic-scale friction with composite oscillator model

A model called composite oscillator model is proposed for studying energy dissipation mechanism of atomic-scale wearless friction. The model consists of the whole macroscopic oscillator and the micro oscillators of interfacial atoms. The different influences of the two oscillators on the energy dissipation process of friction are discussed. It is found that the frequency of the interfacial exciting force is the key factor to energy conversion in the friction process by analyzing the dynamics characteristic of interfacial atoms. In the equilibrium stage, the interfacial force acts integrally and uniformly on each atom because its frequency is near zero. In the non-equilibrium stage, however, the distribution of energy received by the interfacial atoms is non-uniform because the frequency of the interfacial acting force is very high. Therefore, the extra energy may be easily transferred to the adjacent atoms to have the energy dissipated. Then, the formulas are derived to calculate a frictional force. The calculated force is found to be close to the experimental one. The comparisons show that the composite oscillator model can explain energy dissipation mechanism in a frictional process and it can be used to control friction as well.