[SY-O8] Temperature dependent dynamics simulation of traction fluid by molecular dynamics method
Traction drive is a mechanism that transmits power by a rotor and lubricating oil. In order to evaluate the characteristics of the fluid molecules in the traction drive, we construct a simulation method to apply shear to the fluid confined between solids using LAMMPS, a molecular dynamics simulator.
In this simulation, conditions are set as follows. The boundary condition of the system is a periodic boundary condition in the horizontal direction. Fluid is composed of a single hydrocarbon compound and the number of atoms is about ten thousand. The solids are a model metal surface imitating (100) plane of α-iron, and thier atomic motion is frozen. The force field parameter of fluid molecules uses the Dreiding force field. Apply a pressure of 0.8 GPa to 1.24 GPa in the direction perpendicular to the solid atoms. Furthermore, a constant slip of relative sliding speed 1 m/s to 50 m/s is applied. Then, the simulation time on the order of nanoseconds is passed and the steady state is set. With the above setting, an ensemble of constant pressure / constant shear state is created.
The temperature dependency of the coefficient of traction is evaluated by changing the temperature of the fluid from -20 ° C to 140 ° C. The coefficient of traction also change with the change of temperature, and the tendency is at least qualitatively consistent with the experimental values.
In this simulation, conditions are set as follows. The boundary condition of the system is a periodic boundary condition in the horizontal direction. Fluid is composed of a single hydrocarbon compound and the number of atoms is about ten thousand. The solids are a model metal surface imitating (100) plane of α-iron, and thier atomic motion is frozen. The force field parameter of fluid molecules uses the Dreiding force field. Apply a pressure of 0.8 GPa to 1.24 GPa in the direction perpendicular to the solid atoms. Furthermore, a constant slip of relative sliding speed 1 m/s to 50 m/s is applied. Then, the simulation time on the order of nanoseconds is passed and the steady state is set. With the above setting, an ensemble of constant pressure / constant shear state is created.
The temperature dependency of the coefficient of traction is evaluated by changing the temperature of the fluid from -20 ° C to 140 ° C. The coefficient of traction also change with the change of temperature, and the tendency is at least qualitatively consistent with the experimental values.