Nonlinear Dynamic Behaviors of Rotor System with Misaligned Journal Bearings

Abstract

The dynamic modeling of a rotor system on misaligned journal bearings is discussed and its nonlinear dynamic behaviors are considered in this paper. Firstly, a dynamic model of six degrees of freedom system is established under the conditions of the long bearings, small bearing misalignment and mass unbalance. Then, the nonlinear dynamics of the rotor-bearing system, such as the displacement response and its frequency spectrum, rotor orbit and its Poincare map are analyzed by the Runge-Kutta method. The results show that at low speed the steady-state responses of the rotor system in lateral direction is synchronous, as the speed increases a serious of bifurcation phenomena and chaotic oscillations occur. In many cases, there exist the integer multiples components of the rotating speed except the synchronous one in displacement responses.