Study On The Friction Coefficient Of Elastohydrodynaic Lubrication With Wall Slippage

This project focuses on the friction characteristics of an elastohydrodynmaic lubrication contact when wall slippage occurs。For accurate measurements of friction coefficients with wall slippage, an optical test rig was revised. A friction measurement system has been deliberately developed. A real time observation of the change of film shape with wall slippage was carried out from a machine vision system and the friction was collected at the same time.Detailed studies has been carried out to investagte the influences of the resistance , which is form the support bearing system of the glas disc, on the friction force measurmenet. The results showed that the resistance of the support bearing cannot be ingnored when measuring the firction force. From the test data, a regression formula has been obtained to calibrate the measured friction force.Experiments have been carried out to study the start-up friction of an elastohydrodynamic lubrication contact with an entrapped lubricant under spure sliding consitions. In experiments, the point contact was formed by ball-disc contact. The friction coefficients were measured with entrapped lubricants and without entrapped lubricants. Furthermore, the influence of entrapped lubricant quantities on the firciton has also been showed.Variations of the friction coefficients have been obtained experimentally in the occurrence and disappearance of an inlet dimple in an elastohydrpdynamic lubrication contact . The influences of entrainment speeds, loads and oilds on the friction have also been discovered. Furthermore, comparison was made between the friction coefficient curve from experiments and the classical Stribeck curve, and a preliminary theoretical analysis was given to account for the difference between them.A full numerical solution was finished to theoretically confirm the experimental friction coefficients. A circular limiting shear stress model was chosen as the rheological model in the present numerical simulation. Variation of the friction coefficients with loads, entrainment speeds were compared with experimental results qualitatively.