Abstract: The nano-scale thin film lubrication of two kinds of lubricants, pure tridecane and tridecane with polyhedral oligomeric silsesquioxanes material T8H8 added (the mole fraction of T8H8 is 10%), at different shear velocities are studied. Firstly, the interaction model of long chain molecules is built. Then the average shear stresses, the distribution of velocities, densities and temperatures of two kinds of lubricates at four different shear velocities, 1 m/s, 5 m/s, 10 m/s, 20 m/s, are obtained by the mo-lecular dynamics simulations. Some special physical phenomena were investigated also. The results indicate that the phenomena of delamination and slippage between layers appear at each shear velocity of the two kinds of lubricants. These phenomena generally occur in nano-scale thin film lubrication. Along with the unceasing increase of the shear rate, the temperatures of the two kinds of lubricants increase continuously. At each shear velocity, the central layers of the two kinds of lubricates get the maximum temperatures always. The results also show that the shear stresses and the temperatures decreased observably after the T8H8 is added into the tridecane. The T8H8 can greatly improve the lubrication effect of the tridecane lubricant.

Key words: Molecular dynamics simulation, Lubrication, Polyhedral oligomeric silsesquioxanes, Tridecane