鎖状分子系におけるトラクション発現の分子動力学解析

抄録

In the traction drive, when transmitting power, a high pressure of about 1.0 GPa is applied to the oil film in the contact area, and an EHL (elasto-hydrodynamic lubrication) oil film is formed. This EHL oil (traction fluid) film is nessesary to have both the ability to form an oil film on the sliding surface to act as a lubricating oil and the property of efficiently transmitting traction force. Investigate the effect of fluid molecules on the shear field is important. In this study we use molecular dynamics simulation applying a shear field to long-chain fluid molecules confined between solids. The force field parameter of the simulation is GAFF, and a constant pressure of 1.0 GPa is applied vertically. Shear force is applied by moving the solid atomic layer at a constant speed. As a result, the fluid film becomes in an elastohydrodynamic lubrication state. The boundary condition is a periodic boundary condition in the horizontal x and y directions, and a constant pressure and constant shear state is created by calculating the time evolution of 0.5 fs in time steps. The state where the shear field in the fluid is constant is judged to be the steady state in the constant pressure and constant shear field, and the traction coefficient is evaluated. As a result, it can be seen that fluid molecules at a certain distance from the solid layer are enough to bind by interatomic interaction, and that the fluid molecules are pulled to create a shear field. Calculated from the change over time in the traction coefficient of the chain molecular fluid when a simulation was performed by applying a relative slip velocity of 100 m/s to the system. Since the time step was 2x106or later and the traction coefficient was in a steady state fluctuating on a constant baseline, it was determined to be in a constant pressure and constant shear state. Thereafter, the average traction coefficient was calculated, and μ = 0.42.