Theoretical and Experimental Study on the Dynamic Characteristics of Tilting Pad Thrust Bearing Considering Excitation Frequency

Abstract

A modeling and testing method of dynamic characteristics considering excitation frequency of tilting pad trust bearing are proposed to study the effect of the excitation frequency on its dynamic characteristics. The excitation frequency is introduced into calculation process of dynamic coefficients of tilting pad thrust bearing according to the definition of stiffness and damping of tilting pad bearings. The mathematical model of its dynamic characteristics containing excitation frequency is deduced through establishing fluid film thickness equation, Reynolds equation and equation of tile motion under the condition of axial disturbance. The variation of stiffness and damping with perturbation frequency, that is, the ratio of excitation frequency to spindle rotation frequency, speed and load are analyzed. Test results of stiffness and damping in different excitation frequency, rotation speeds and loads are obtained in the test rig of tilting pad trust bearing by using impulse excitation method. The following conclusions are obtained through analyzing the theoretical and test results. When the perturbation frequency is small, the stiffness of tilting pad thrust bearing increases gradually with its enlargement, the damping is just the opposite. While the stiffness and damping tend to be stable gradually after perturbation frequency increases to a certain degree. In addition, the amplitude of variation of stiffness and damping with perturbation frequency is little affected by speed and load.