Nonlinear vibration signature analysis of a rotor supported ball bearings

The dynamic behaviour of a high speed balanced rotor supported on deep groove ball bearings (SKF-6205) has been studied by numerically simulated results. Since, internal radial clearance (IRC) is inevitably present in all class and types of bearing, in this paper it (IRC-C3) is considered as main source of nonlinearity with speed as control parameter. The complex mathematical model simulates nonlinear vibrations due to both nonlinear contact stiffness and damping at the contact of rollers and races. The contact of rollers with races are treated as nonlinear springs with contact damping whose stiffnesses are obtained by using Hertzian elastic contact deformation theory. The explicit type numerical integration technique Runge-Kutta-fourth-order method is used to solve the coupled nonlinear differential equations iteratively. Various techniques like Poincaré maps, orbits plots, and power spectra are used to study the nature of response. At lower speed transient chaos is observed which becomes stable through periodic doubling bifurcation at the medium speed. Hopf bifurcation is also observed at higher speed due to emergence of limit cycle.