Analysis Of The Oil-supply Condition In Thermal Elastohydrodynamic Lubrication Of Point Contacts

Elastohydrodynamic lubrication (EHL) under different oil-supply conditions was studied mainly in this thesis. Five problems were included, i.e., an analysis of the oil starvation in the EHL point contacts under a special oil-supply condition; an analysis of the oil starvation in the EHL point contacts with the degradation of oil-supply condition; a study of starvation in non-Newtonian EHL elliptical contacts with different entrainment; and, a study of starved experiments and an effective algorithm of the thermal EHL of J-T fluid.First of all, according to the starved phenomenon observed in optical interferometry experiment, a special oil supply condition was proposed. Full numerical solution of EHL in point contacts was obtained using the proposed oil-supply condition. Through this work, an effective algorithm of starved EHL was mastered as the base for further study. It was found that, the lubrication performance of an EHL contact is dominated by the quantity of the supplied oil, however, it can also be influenced by the distribution of the supplied oil layer.Secondly, the degradation process of the oil-supply condition was studied, and it was revealed that, in the starved EHL point contacts with degradation of oil-supply condition, the lubrication is in the fully-flooded state at first, and then changes into the starved state, and at last, achieves a steady starved state. The relations of the thickness of the supplied oil layer, central and minimum film thicknesses, the formating position of the lubricating film, and the traction coefficients with the time of lubrication were investigated. In addition, thermal effect was taken into account and the variations in the thermal distributions were demonstrated.Then, the non-Newtonian Ree-Eyring flow conception was introduced into the analysis, and the problem of the EHL of elliptical contacts with different entrainment was solved numerically. The relations of the entrainment and the formation position of the lubricating film, and the central and minimum film thicknesses were analyzed. The variations in the central and minimum film thicknesses and the traction coefficients versus entrainments with different loads, oil-supply conditions, velocities and slide-roll ratios were given.Finally, the starved experiments were carried out in optical EHL test rig under pure rolling conditions, meanwhile numerical simulation was carried out for the classical starved phenomenon and compared with the experiments qualitatively.In addition, an effective algorithm of thermal EHL of J-T fluid was developed, and the performance of the lubrication in the fully-flooded state was discussed considering the influence of the J-T non-Newtonian flow.