Bifurcation analysis of a rotor-bearing system with temperature-dependent viscosity

A flexible rotor supported by two journal bearings under nonlinear suspension and the lubricating oil is assumed to be temperature dependent in this study. Analytical tools were inclusive of bifurcation diagrams, dynamic trajectories, power spectra, Poincaré map, fractal dimension, and Lyapunov exponent are used to verify the dynamic characteristics of the rotor-bearing system, and abundant periodic, subharmonic, quasi-periodic, and even chaotic motions are found in this study. From the simulation results, the higher operating temperature will also cause the dynamic trajectory of the system to become non-periodic vibration. The rotor-bearing system operating in a non-periodic motion state may lead to possible broadband vibration with large amplitude and increase the possibility of fatigue or failure of the system. Such simulation analysis will help engineers avoid unnecessary trial and error when designing and applying rotor-bearing systems.