Bifurcation in a flexible rotor supported by short journal bearings with nonlinear suspension

The hydrodynamic journal bearings-rotor system is a common machine element that is strongly nonlinear due to oil film forces. In this study, bifurcation of the response of an unbalanced bearings-rotor system with nonlinear suspension is investigated based on the assumption of an incompressible lubricant together with the short bearing approximation. Theoretical bifurcation analysis of bearing center motion is carried out by means of numerical investigation, the procedure here being numerical integration. The six major parameters characterizing the theoretical model of the system are considered with nondimensional speed. Jump phenomena, subharmonic and quasi-periodic vibrations of the bearing center trajectory, are found in this system. It is concluded that the bearing center trajectory had undesirable nonsynchronous vibrations. Understanding the bifurcation behavior of these parameters provides theoretical and practical ideas for controlling bearings-rotor systems and optimizing their operation.