Abstract
Force and thermal effect are dominant in giving rise to variation of bearing dynamic stiffness and vibration. On the basis of test and theoretical analysis, the dynamic stiffness and vibration model of angle contact ball bearing considering vibration and friction state variation is established. Firstly, based on the quasi-statics of bearing and hydrodynamic lubrication theory, the motion and force relation between each parts are determined by considering the force and thermal effect. Secondly, the friction power consumption of bearing is calculated adopting integrated method, besides, the conduction heat resistance and convection heat resistance in the bearing system are achieved. A steady-state temperature calculation model of angle contact ball bearing-shaft-house system is built based on thermal network method. Finally, the dynamic stiffness and vibration model of angular contact ball bearing including the thermal-solid coupling effect is obtained, which is employed to realize the theoretical analysis of bearing dynamic stiffness and vibration, its accuracy is verified through typical test results. The calculation results shows that there is a good agreement between house test temperature and calculation temperature. The evolution rule of contact deformation and contact stiffness between ball and outer/inner ring over the whole life under excessive preload is the same. So does the oil film thickness and oil film stiffness. However, the curve shape and amplitude of contact angular between ball and outer/inner ring over the whole life is different. Bearing radial stiffness value has a more significant change than axial stiffness value, both of them represent an overall upward tendency. The radial clearance holds a negative correlation with house temperature, however, the radial displacement has a positive correlation with house temperature. The evolvement curve of contact angular affected by various preload and speed is opposite. The contact load between ball and outer/inner ring has the same trend influenced by preload and speed with EHL. The variation of preload has bigger effect on temperature rise than speed change. The oil film has little influence on contact angular, contact load and temperature under dry-lubricated or lightly lubricated condition.
Highlights
Dynamic stiffness of angular contact ball bearing is the contact characteristic between ball and outer and inner ring raceway during bearing is running, that is, it is a transient value
Its dynamic stiffness tends to be changeable affected by force and thermal effect, which would have the vibration of bearing-rotor system increase and even induce rub-impact between blade and shell
There is a small quantity of literatures for bearing dynamic stiffness, which are mainly focus on the effect of geometrical structure parameters, number of rolling element, rotational speed, external load, and thermal effect acting on bearing contact deformation and oil film thickness [1, 25, 30, 31]
Summary
Dynamic stiffness of angular contact ball bearing is the contact characteristic between ball and outer and inner ring raceway during bearing is running, that is, it is a transient value. In the operation process of bearing, the oil film thickness between rolling element and outer/inner ring raceway has a great impact on contact characteristics of bearing [1] People pay their attention to conduct a study on bearing dynamic stiffness by means of introducing quasistatics of bearing and elastohydrodynamic lubrication theory. There is a small quantity of literatures for bearing dynamic stiffness, which are mainly focus on the effect of geometrical structure parameters, number of rolling element, rotational speed, external load, and thermal effect acting on bearing contact deformation and oil film thickness [1, 25, 30, 31]. In this paper, considering variation of vibration and friction state between mating part surfaces, a bearing dynamic stiffness analysis model is built considering thermal-solid coupling effect based on quasi-statics of bearing and elastohydrodynamic lubrication theory, which is used to analysis performance degradation mechanism in the whole life of bearing.
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