An enhanced electromagnetic-based nonlinear energy sink for hybrid passive control and energy harvesting from resonant vibrations

The application of nonlinear vibration absorbers in a variety of dynamic systems is attracting significant attention . The so-called nonlinear energy sink (NES) has the ability to provide high vibration attenuation in a broad frequency with robustness. However, the effectiveness of this device can be limited with the increase of excitation, as it may induce high amplitude (i.e., detach zone) oscillation and leading to sudden failure. To address these limitations, this work proposes an investigation into an electromagnetic-enhanced nonlinear energy sink (NES-EH) aiming to combine hybrid vibration control and energy harvesting. The device comprises the conventional NES, with a cubic stiffness spring, coupled with a magnet-coil assembly. The electro-magneto-mechanical coupling provides nonlinear damping dynamics allowing mitigation of the detached zone and an efficient conversion of the absorbed energy into electrical power. Two different assemblies, varying the relative static position of the magnet coil, are considered to explore alternative nonlinear damping models. The harmonic balance method is used to build analytical solutions to characterize the dynamics of coupled systems. After a numerical validation of the analytical approach, a complete characterization of the system dynamics is performed regarding frequency-response and slow invariant manifold (SIM) curves. Parametric analysis and optimization procedure are employed to design the NES-EH parameters. The performance of the designed absorber is compared with the classical NES solution, and their robustness is also investigated.