Nonlinear vibration suppression of a dual-rotor system with combined misalignment using the nonlinear energy sink

Misalignment in aero-engine rotor systems increases vibration and contributes to bearing failures. This study investigates a shared bearing bore-coaxial dual-rotor system with combined misalignment of couplings and bearings, analyzing its vibration characteristics and exploring vibration suppression strategies using the nonlinear energy sink (NES). A unified nonlinear restoring force model considering the misalignment of roller and ball bearings is developed, and the dynamic equations of the dual-rotor system with combined misalignment are derived. The NES is modeled using Lagrange's method and integrated into the dual-rotor system to suppress vibration. Optimal NES parameters are obtained using a genetic algorithm with the objective of minimizing amplitude. A roller bearing-rotor system test rig was constructed to validate the misaligned bearing model. Finally, the effect of NES on suppressing vibrations is analyzed, along with the influence of NES parameter variations on the dynamic characteristics. The results indicate that NES effectively reduces the vibration near critical speeds and the resonance peaks caused by misalignment, introduces a modulation frequency interval (f_r1-f_r2), and leads to different motion states in the rotor system.