Fluid Film Bearing Dynamic Coefficients and Their Application to Structural Finite Element Models

A review of methods currently employed for modeling static and dynamic characteristics of fluid film bearings is provided. In nearly all cases, the literature discusses the use of dynamic coefficients for low-order rotor-dynamics models in which a single stiffness and damping matrix is used to connect an individual rotor node to an individual statorbearing node along the shaft centerline. The focus of the present work is on developing dynamic coefficients for high-order structural finite element models, which use a distribution of the coefficients over the journal circumference. While the methods presented here are applicable to many bearing types, the focus is on the most common bearing, the plain and tilting pad bearing designs. A numerical study is provided to show the importance of properly implementing the bearing coefficients by comparing the results for two methods of coefficient implementation for a rotor model. The results show differences in rotor-to-stator transfer accelerance, resonance frequencies, and damping levels.