Nonlinear Dynamic Analysis of Rotor-Bearing-Pedestal Systems With Multiple Fit Clearances

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 rotorbearing-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.

Investigation of Nonlinear Forced Vibrations of the “Rotor-Movable Foundation” System on Rolling Bearings by the Jacobi Elliptic Functions Method

“…In addition, for the most complete analysis of the process, it is important to take into account the influence of such factors as the asymmetry of the installation of the rotor on the shaft, i.e., imbalance, variability of inertial parameters, various positional forces, external friction, mobility of the foundation, etc. The impact of foundation vibrations on the linear dynamics of the "rotor-bearings" system and, in particular, on rotor vibrations was studied in detail in [5,6,10,11,30,31].…”

“…In Refs. [30,31], mathematical models of the "rotor-bearing-foundation" system, in a linear formulation, with the rotor shaft located horizontally, are presented. In a nonlinear formulation, this problem was partially considered and analyzed by the method of complex amplitudes in [32,33].…”

Mechanism and Characteristics of Global Varying Compliance Parametric Resonances in a Ball Bearing

“…Bai et al [35] established a 6DOF nonlinear ball bearing-rotor model and found that the occurrence of 2-order subharmonic resonance is provoked by the coupling of Hertzian contact and internal clearance nonlinear factors of ball bearings. Wu et al [36] noted that the subharmonic hysteretic resonance become significant and the resonance amplitude moved to lower frequencies as the assembly gap increased for an angular contact high-speed ball bearing system. However, these studies [33][34][35][36] relate to the case of external excitations from unbalanced rotors, for which a small excitation produces a large response only if the frequency of the external excitation is close to that of the linear natural frequency of the system, and it is essentially different from that of the parametric excitation system.…”

“…Wu et al [36] noted that the subharmonic hysteretic resonance become significant and the resonance amplitude moved to lower frequencies as the assembly gap increased for an angular contact high-speed ball bearing system. However, these studies [33][34][35][36] relate to the case of external excitations from unbalanced rotors, for which a small excitation produces a large response only if the frequency of the external excitation is close to that of the linear natural frequency of the system, and it is essentially different from that of the parametric excitation system. Therefore, a global mechanism analysis of VC parametric resonances in rolling bearings is necessary.…”