A tunable electromagnetic nonlinear energy sink

Nonlinear energy sink (NES) is a significant technology for nonlinear vibration reduction. However, one of its inherent limitations is the need for specific energy thresholds, necessitating multifunctional designs to activate a strongly modulated response (SMR). Nonetheless, previous achievements have been confined to modifications in the initial installation conditions alone. To overcome this limitation, a novel tunable electromagnetic NES (TE-NES) is proposed, which allows for various characteristic modifications through online current adjustment. The nonlinear electromagnetic force is computed using the filament method. By coupling TE-NES with a linear oscillator, a slow invariant manifold (SIM) is obtained by using the multiple scales method. Furthermore, the complexification-averaging method is utilized to obtain analytical solutions for the frequency responses. The observed nonlinear behaviors are analytically explored and numerically validated, revealing that adjusting the current allows for switching between monostable, bistable, and tristable NES. Additionally, performance variations caused by manufacturing errors, wear, and external environmental influences can be effectively mitigated through current regulation. In the face of varying excitation levels, the current magnitude can be adjusted to generate the desired SMR. Notably, the TE-NES facilitates the regulation of dual unstable regions by current, enhancing the robustness and adjustability of coupled system. This enables the TE-NES to demonstrate a novel phenomenon of dual SMR. The flexibility to adjust the current in response to varying excitation levels and different characteristics of the linear oscillator enables optimal vibration reduction performance.