Molecular dynamics simulation of nano-scale thin film lubrication and its modification

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 molecular dynamics simulation. 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 lubricants 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 tridecane.