Distributed journal bearing dynamic coefficients for structural finite element models

A physics-based method to circumferentially distribute journal bearing dynamic coefficients is presented. The method is based on the traditional perturbation approach for developing linearized bearing coefficients. The focus of this paper is on the plain and tilting pad bearings, but the method is applicable to any bearing model that is developed using the perturbation approach. When used for tilting pad bearings, the method removes the effect of the pad rotational degree of freedom on the computed coefficients, and thus eliminates the need to assume a pad vibration frequency to reduce the coefficients to the usual eight-coefficient representation. A numerical study is performed to show the effect of coefficient distribution for a flexible rotor/stator structure. The results of the study show a significant effect of the distribution method on the bearing coupling characteristics.