A New Vibration Model for a Bearing-Rotor System considering a Bearing Structure

Abstract

In the past researches about bearing-rotor systems, rolling element bearing was commonly simplified as a non-linear spring—damper with radial stiffness and damping. Such an assumption neglects the influences of bearing geometry structure on the governing equations of a bearing-rotor system and is not so reasonable. In this article, the contact stress and load distribution between roller elements and raceways are analysed using Hertz theory and the calculation method for bending moment on the bearing end faces is established; on this basis a new transfer relationship of state vectors between the two ends of bearing is obtained, and then a new transfer matrix method (TMM) for a rolling element bearing-rotor system is established. A concrete calculation example of a cylindrical roller bearing-rotor system is carried out using the new TMM. With this example, the influences of cylindrical roller bearing structure parameters (roller length, roller radius, and roller number) on a rotor system's vibration characteristics were studied in detail, and the obtained results show that the bearing geometry structure has significant influence on the rotor modal shape and the unbalanced response; such influences were also verified by finite-element method analysis.