Abstract
Dynamic analysis of a rotor-bearing-pedestal system with multiple bearing clearances is conducted in this study. Firstly, Jones-Harris method is used to deduce the equivalent nonlinear support stiffness of angular contact high-speed ball bearing with preload considered. Ignoring the structural deformation, the contact model of inner and outer rings with clearance is used to describe the clearance fit between the outer ring and the sleeve, and between the sleeve and the bearing pedestal. Based on Hertz contact theory, the discontinuous and nonlinear support stiffness is then obtained. The lumped parameter model of rotor-bearing-pedestal system is established and verified based on dynamic test results. Based on this, the influence of clearance fit parameters and external excitation parameters on the vibration response amplitude of the system is analyzed. When the radial displacement is greater than the fit clearance, the radial support stiffness changes abruptly and increases rapidly. If it increases to a certain value, the increase of radial stiffness would slow down. The vibration response curve appears sub-harmonic resonances and amplitude jump. The increase of the fit clearance aggravates the vibration response level, the resonance speed of the system moves to the low speed, and the jumping phenomenon becomes more prominent, which is not conducive to the stable operation of the rotor system.
Highlights
In order to facilitate assembly and reduce the adverse effects of working state changes on the operation of the rotating machinery, it is an effective way to design reasonable clearance in the bearing structure [1]
The bearing fit clearance brings discontinuous characteristics of bearing stiffness, which might have a negative impact on the dynamic characteristics of high-speed flexible rotor
In order to reasonably design the mating clearance and ensure the stable and reliable operation of the highspeed flexible rotor, it is necessary to study the mechanical behaviors of the fit clearance and its influence on the dynamic characteristics of the flexible rotor [2]–[4]
Summary
In order to facilitate assembly and reduce the adverse effects of working state changes (such as temperature rise) on the operation of the rotating machinery, it is an effective way to design reasonable clearance in the bearing structure [1]. Based on the rotor rigid element model and lumped parameter model, Cao et al [28] established a model considering the fit clearance between the bearing outer ring and the pedestal, and the phase trajectory plots were used to illustrate the stability changes of the system under the influence of the fit clearance. These studies assumed that the contact stiffness between the bearing outer ring and the pedestal is constant.
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