Efficiency evaluation of the enhanced nonlinear energy sink with electromagnetic energy harvesting mechanism

Nonlinear energy sinks (NESs) have received considerable attention in vibration suppression, and the optimal design around the stiffness and damping is considered the key to achieving improved performance. This paper investigates the tri-magnet monostable and bistable enhanced NESs with electromagnetic energy harvesting mechanism. A comprehensive evaluation of the absorption and harvesting efficiency of the enhanced NES is conducted. The tri-magnet structure is developed further to realize both monostable and bistable configurations. Then, an enhanced series coils energy conversion element based on the electromagnetic energy harvesting mechanism is proposed for damping adjustment. The NES is attached to the cantilever beam subject to transient excitations. Furthermore, the equivalent model of the cantilever beam with an NES is obtained by exploiting the extended Hamilton's principle. An optimization design method that considers both vibration absorption and harvesting efficiency is provided. The instantaneous energy variations of the optimized monostable and bistable NESs are discussed based on simulation and experimental results. Finally, the experiments with two load modes, R load and C load, demonstrate the effectiveness of the enhanced NESs in vibration absorption and its promising application in energy harvesting.