Influence Of Positive And Negative Precession Of Axis Trajectory On Dynamic Characteristics Of Sliding Bearing

Axis trajectories of sliding bearings not only comprehensively reflect the working condition,but also contain a wealth of fault information.It is of great importance for the study of dynamic characteristics and the stability analysis.The positive and negative precession of axis trajectory is taken as the research object to analyze its influence on dynamic characteristics of the sliding bearing.The main contents of this paper are as follows:1.The calculation model of the nonlinear axis trajectory and dynamic characteristic coefficients of the oil film considering the friction force are established based on Reynolds equation and flow balance equation and verified by the comparison of the calculation model of the linear axis trajectory.2.The calculation model of the predesigned oval and round axis trajectory are founded on the basis of predesigned axis trajectory forming principle.The method for discriminating the precession direction of axis trajectory is proposed based on the full-spectrum analysis theory.The self-correction of the predesigned axis trajectories at stable and critical speeds is analyzed.3.Various non-dimensional numerical indicators are introduced.The static equilibrium model is built by using the average value of the axis displacement in a given calculation period,and the critical speed model is given with the use of logarithmic decay rate.The dynamic characteristic coefficients and non-dimensional numerical indicators of the journal center and each point on the predesigned round and oval axis trajectories with different bearing parameters are calculated in order to research on the characteristics of positive and negative precession of the sliding bearing.4.The experiment of the axis trajectory of sliding bearing is designed.The signals of vertical and horizontal displacements in the same section are collected by eddy current sensors.The original signals are analyzed and processed by Fast Fourier Transformation.The nonlinear axis trajectories of the sliding bearing at different speeds are obtained.The expressions of the fundamental frequency trajectories are given and the fundamental frequency trajectories are drawn.The axis precession direction of the gotten axis trajectories are judged using the full spectrum analysis theory.