Dynamic Analysis of Overhung Rotor System with Bearing Defect

In this paper an analytical model is proposed to study behavior of overhung rotor-defective bearing system. Overhung rotor is considered with unbalanced mass and bearing is taken as cylindrical roller bearing having surface defect. To analyze all system component’s effect at one node, finite element method is used to predict exact system vibrations. Euler-Bernoulli’s beam element is used to discretize shaft. Gyroscopic effect of overhung rotor is also taken into account. Governing equation of motion has been modified according to our system. Hertz contact stress theory is used for every roller-race contact to calculate overall nonlinear bearing force. Governing differential equation is solved by newmark-beta time integration method. Nonlinear matrix equation which is generated at each time-step in newmark’s method is solved by Broyden’s quasi-newton method. Results at defective bearing is obtained and plotted in time and frequency domain. Higher level Poincare maps are drawn to view system’s minimum stability time. Whole analysis work is done in software package MATLAB. The current study provides a powerful tool for design and health monitoring of overhung rotor systems.