Dynamics of Pivoted-Pad Journal Bearings, Including Pad Translation and Rotation Effects

Abstract

Pivoted-pad journal bearings are commonly applied to highspeed rotating equipment because of their potential for stable operation. Analysis of such bearings is complicated by the ability of each pad to pivot as the shaft is displaced, and to translate radially due to pivot flexibility. This leads to dependence of linearized stiffness and damping coefficients on shaft vibrational frequency, as well as shaft rotational frequency. Pad inertia and mass effects also couple into the response of the bearing, and become significant in large bearings. This paper describes an approach to combine the above effects with the pad assembly technique often used to develop bearing properties. A reduced matrix can be developed once a vibrational frequency is assumed. The approach provides a flexible, yet computationally efficient, means of obtaining bearing properties for rotor dynamics calculations. Presented at the 37th Annual Meeting in Cincinnati, Ohio, May 10–13, 1982