Axial vibration reduction and energy harvesting for marine thrust bearings based on BNES-EMS considering bistable behavior

The marine propulsion shaft experiences continuous axial vibration induced by the non-uniform wake field of the propeller. Although this vibration affects navigation safety, it may potentially serve as a source of vibration energy. A bistable nonlinear energy sink system integrated with an electromagnetic energy harvester (BNES-EMS) is designed to achieve synergistic vibration reduction and energy harvesting. A three-mass dynamic model incorporating negative stiffness and cubic nonlinear stiffness is established to accurately capture the bistable behavior and reveal the targeted energy transfer. Numerical simulations are conducted to evaluate the vibration mitigation and energy harvesting performance of the proposed integrated BNES-EMS using measured vibration excitation. The results demonstrate that the BNES-EMS effectively redirects vibrational energy from the primary system to the absorber, generates substantial output voltage, and achieves superior displacement amplitude reduction. Parametric discussions indicate that increasing absorber mass enhances both vibration suppression and energy harvesting, while coil turns has an optimum for power output. Furthermore, bistable topology coupling analysis elucidates the operational adaptability of low-barrier narrow-well versus high-barrier wide-well configurations under varying operating conditions. This study provides a theoretical basis for the parameter optimization and practical application of the integrated vibration reduction and energy harvesting device for marine thrust bearings.