Nonlinear dynamic behavior of a water-lubricated hybrid bearing-rotor system
In this study, the stability analysis is carried out on a water-lubricated hybrid bearings used as the support of a high-speed motorized spindle. A two-dimension finite element method considering turbulence effect has been developed to solve the nonlinear oil film force. This paper mainly studies the influence of the water supply pressure, rotating speed, and unbalance mass on the axis orbit of the rotor-bearing system. The results of the axis orbit indicate that the effect of nonlinear for the hybrid bearing studied in this paper is not obvious, and the bearing-rotor system can run safely and stably at the rotating speed not more than 30000 rpm.
A study of steady state and transient performance characteristics of a flexible shell journal bearing
Abstract A computer-aided study of static and dynamic performance characteristics and linear and nonlinear transient motion analysis of a flexible shell journal bearing system is presented. Trajectories of the journal-centre motion have been drawn to predict the transient response of the system. It is concluded on the basis of results presented in this paper that the motion trajectories obtained using nonlinear equations of motion give a much higher stability margin in terms of critical mass than those obtained through linearized analysis.
The Effect of Perturbation Amplitudes on Eight Force Coefficients of Journal Bearings
This paper investigates the relationship between eight linear oil-film force coefficients of circular journal bearings and the perturbation amplitudes. The force coefficients are calculated by the finite perturbation method and compared with those calculated by the infinitesimal perturbation method. Numerical experiments show that the calculated results from both finite perturbation and infinitesimal perturbation methods are very close (with a variation less than 0.1 %) when the perturbation amplitudes are less than 0.02c (displacement) or 0.02ωc (velocity) for normal bearing eccentricities. For eccentricities between 0.2 and 0.8, the calculated coefficients by the finite perturbation method will differ less than 2.5 % from the results by the infinitesimal perturbation method if the perturbation amplitude is less than 0.05c or 0.04ωc. The bearing coefficients calculated by the finite perturbation method under different perturbation amplitudes are presented graphically.