paper Multi-mode vibration suppression of a floating raft system via a tristable nonlinear energy sink

To reduce the multi-modal vibrations of the floating raft system in the low-frequency range, a tristable nonlinear energy sink (TNES) is designed and applied. The model of the floating raft system is developed, followed by a modal analysis. The multi-stable characteristics of the TNES are generated through the combination of the vshaped beams and the permanent magnets, and the proposed TNES is implemented in the floating raft system. The parameters of the TNES under harmonic and shock excitations are designed using an optimization algorithm. The performance of the TNES is verified under both single-machine and dual-machine conditions. Furthermore, experimental tests are conducted to further validate the vibration reduction characteristics of the TNES. The results demonstrate that when the single vibratory machine operates, the system responses exhibit significant amplitudes at various modal frequencies. When the dual vibratory machines operate, the system automatically cancels out the amplitude at the eigen-frequency of mode 2. Meanwhile, the TNES effectively suppresses the multi-modal vibrations of the floating raft system. In the simulations, the suppression rate of the TNES exceeds 60%, while in the experiments, it surpasses 42.71%.