It is necessary to use the thermal network method for thermal analysis of the bearing, but there are still some shortcomings. In this paper, a novel thermal network model of the bearing transient temperature is developed considering the thermal-fluid-solid coupling effects. First, the quasi-static analysis of the bearing is carried out considering the thermal expansion effect, and the heat generation, heat transfer, and heat dissipation are studied. Then, the coupling effects between the oil characteristics, heat generation, structure parameters, and temperature (thermal-fluid-solid) during the operation of the bearing are discussed, and the transient thermal network model of the bearing-shaft-bearing housing system is established. Test results indicate that the existing models (without thermal-fluid-solid coupling) have large temperature deviation, while the proposed model in this paper considering the thermal-fluid-solid coupling effects is much more accurate. Finally, the effects of rotational speed, load, oil temperature, and oil flowrate on the temperature rise are all achieved and discussed.
Hydrogenated carbon films (CHx) with different hydrogen content percentages have been examined. Drag tests on CHx coated disks, using 50 percent Al2O3/TiC sliders, with and without carbon coating on the slider air bearing surfaces (ABS), were conducted in an ultra high vacuum chamber equipped with a mass spectrometer. Mass fragments of lubricant released from the head disk interfaces were recorded in real time along with friction measurements. The results show that a higher hydrogen content in the carbon overcoat can improve wear durability by reducing the friction coefficient and affecting the chemical reactions between the sliders and the lubricant. A carbon overcoat on the slider ABS can protect Z-dol lubricant from catalytic reaction with the Al2O3 in the slider material. The wear durability at the head disk interface is controlled by combined mechanical and chemical factors, which are defined by the atomic structures of the contacting surfaces.
A dynamic model of angular contact ball bearing considering non-Newtonian behavior and interaction between balls and cage is deduced to predict cage slip. And then the cage slip are investigated and compared with measured results under different rotational speeds and axial loads to verify the proposed dynamic model of bearing. It is concluded that the results based on the non-Newtonian behavior of elastohydrodynamic lubrication is more agreement in trend with the tests than that based on the Newtonian assumption, and so the non-Newtonian behavior of elastohydrodynamic lubrication are needed in the cage slip analysis.
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