Effect of particles on lubricated friction - verification of dead time phenomenon and friction theory

摘要

In an attempt to reveal the mechanism of friction generated by solid particles in oil, this study verified the theoretical analysis of friction generation that the authors reported previously (Tomimoto and Mizuhara (1999), Mizuhara et al. (2000)). These previous studies performed theoretical and experimental analysis on the assumption that particles that generate friction (interference particles) were larger than the minimum oil film thickness. In the authors' previous work, they proposed a model of dead time (non interference) phenomenon to describe a phenomenon that friction force was saturated along with an increase in the number of interference particles. It was revealed that friction force, generated by particles at a constant load while varying sliding velocity and interference particle concentration, could be expressed with three parameters, namely the number of interference particles, load supported by an interference particle and interference time. In the present study, the authors performed experiments to verify the following: (1) Is the definition of interference particle correct? (2) Is it correct that dead time phenomenon actually takes place when the sliding surface is lifted by interference particles? (3) Is it possible to express friction force with the number of interference particles, load supported by an interference particle and interference time not only when the load is kept constant but also when the load is varied? It has been proven in the experiments that particles larger than the minimum oil film thickness generate friction force and that dead time phenomenon takes place when a sliding surface is lifted by interference particles. Friction force is found to be expressed with the number of interference particles, load supported by an interference particle and interference time when the load is varied as well.