Nihon Kikai Gakkai ronbunshu (Jan 2023)
Fundamental characteristics of flat thrust bearing with partial placement of slip areas
Abstract
The pressure for supporting the bearing load is induced by the generation of discontinuity of the shear flow rate in each region only by arranging areas in the slip direction with different slipperiness of fluid. In this report, the generated pressure and friction characteristics, which were important for clarifying the characteristics of disc type partial slip thrust bearing were investigated using three-dimensional modified Reynolds equation considering the slip on the solid surface. It was suggested that the relationship between the shear rate and the slip length which is determined with the film thickness estimated from the friction force measured in this bearing by assuming a pure shear condition can be treated as a two-term slip model. Finite width analysis was performed assuming critical shear rate and constant slip length, and the Stribeck curve and pressure distribution were obtained. The low shear rate region less than critical shear rate is increased in the center side of the disk type bearing for the lighter load and the thicker film cases. Then, the friction for supporting the same load shows the value higher than the friction where slip occurs on the entire surface of the assumed slip area of the bearing. On the other hand, since the entire slip area of the bearing surface approaches a slip state, the film thickness and friction when supporting the same load are the same as those when the entire assumed slip area is on slipping. The influence of such critical shear rate also appears in the results of the radial pressure distribution in disc type bearing, and the calculated pressure on the inner circumference side rapidly decreases due to the presence of the non-slip region on the inner circumference side with low shear rate. And then, this tendency agrees with that of the measured radial pressure distribution.
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