Vibration reduction and energy harvesting on the ship thrust bearing unit excited by a measured shaft longitudinal vibration using NES-GMM

Considering the longitudinal vibration of the ship shaft system, there are disadvantages such as small damping bandwidth of passive control and complicated design of active control. An NES-GMM is proposed by the combination of nonlinear energy sink (NES) and giant magnetostrictive material (GMM) for the vibration reduction and energy harvesting of the ship thrust bearing unit. The vibration reduction effect and energy harvesting of the proposed NES-GMM device are analyzed based on actual measured longitudinal excitation as input signals. The vibration behavior including the transient and harmonic response of the thrust bearing and NES device are calculated. Meanwhile, the kinetic, potential, and damping energies of the primary system and the electrical and magnetic energy harvested by the NES-GMM are obtained. Moreover, the effects of mass, damping, and stiffness of the NES structure are also discussed over a range of rotational speeds. The research demonstrates that energy is irreversibly transferred from the primary system to the NES system. Additionally, more energy absorption and better vibration reduction of the NES-GMM device will be achieved with larger mass and damping of the NES.