Research on nonlinear vibration of a dual-rotor system with combined misalignment of cylindrical roller bearing and coupling

Ball and roller bearings are widely used in the rotor systems of aero-engines. Considering multi-spool engines, the misalignment between the shafts can overload the bearings, lead to their failure, and shorten useful life. In this study, an original and unified nonlinear restoring force model for roller bearings and ball bearings that accounts for misalignment faults is proposed. The non-uniform deformation of the rollers due to misalignment is obtained using the slicing method, while the ball bearings experience changes in bearing parameters. Furthermore, the excitation caused by misalignments in couplings and bearings is considered. A dynamic model of the aero-engine dual-rotor system coupled in the form of a shared bearing bore is developed using the finite element method. A designed on purpose rotor system test bench with roller bearings is set up, and the correctness of the authors’ original dynamics model of misaligned roller bearing is verified by experiments. Finally, the effects of different factors such as speed and misalignment angles on the nonlinear vibration response of the dual-rotor system are analyzed.