Nonlinear Vibration Signature Analysis of High Speed Rotor Due to Defects of Rolling Element

This paper presents a mathematical model to investigate the nonlinear dynamic behavior of a high speed rotor-bearing system due to defects of rolling elements. Two defects have been considered for the study, one defect as off-sized rolling elements and other defect as rolling element waviness. In the formulation, the contacts between rolling elements and inner/outer races are considered as nonlinear springs and also used nonlinear damping, which is developed by correlating the contact damping force with the equivalent contact stiffness and contact deformation rate. The equations of motion are formulated using Lagrange’s equation, considering the vibration characteristics of the individual components such as inner race, outer race, rolling elements and rotor. The highest radial vibrations due to ball size variation are at a speed of the number of balls times the cage speed ( Hz N cage b bp ω ω = ). The other vibrations due to ball size variation are also occur at cage bp kω ω ± , where k is a constant. Due to ball waviness, nonlinear dynamic responses are found to be associated mainly with wave passage frequency ( wp ω ) and ball passage frequency ( bp ω ) with their interactive effects.