The nonlinear energy sink (NES) is one representative nonlinear vibration absorber. Despite the existence of excitation threshold, it has been proven to be superior in terms of working frequency range and/or amplitude of vibration suppression, compared to the linear vibration absorber. In recent years, for single-degree-of-freedom NESs, multistable configurations have been explored. However, currently, there is still a lack of comprehensive understanding and optimization of multiple-degree-of-freedom NESs with multistability under varying excitation level. This work investigates the optimal vibration suppression performance of adjustable parallel magnetic NESs with two repulsive magnets (P-2RMNESs) under different levels of impulse excitations through theoretical modeling and simulation, genetic algorithm-based optimization and experimentation. A model is proposed involving beams in bending. Considering bending and consequent rotation of the tip of the beam on which a magnet is mounted, the magnetic force is represented based on the dipole–dipole model to build the dynamic model of the whole system for numerical simulation. The key structural parameters of P-2RMNESs and other absorbers (i.e. linear vibration absorber and single 2RMNES) are optimized through genetic algorithm under different impulse excitation levels. According to the simulation and experimental results, with the same equivalent mass, the optimized P-2RMNESs demonstrate superior performance compared to their counterpart configurations under different excitation levels. Finally, other factors influencing the performance of P-2RMNESs due to experimental constraints are also investigated through numerical simulation. The results of the research reported here sheds light on the design of effective parallel NESs without increasing mass for impulse response mitigation.

中文翻译：

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脉冲激励下并联磁非线性吸能器的振动抑制性​​能


非线性吸能器（NES）是一种具有代表性的非线性减振器。尽管存在激励阈值，但与线性减振器相比，它已被证明在工作频率范围和/或振动抑制幅度方面具有优越性。近年来，对于单自由度NES，人们已经探索了多稳态配置。然而，目前对于不同激励水平下具有多稳定性的多自由度NES仍缺乏全面的理解和优化。这项工作通过理论建模和仿真、基于遗传算法的优化和实验，研究了具有两个排斥磁体的可调并联磁NES（P-2RMNES）在不同脉冲激励水平下的最佳振动抑制性​​能。提出了一个涉及弯曲梁的模型。考虑到安装有磁体的梁尖端的弯曲和随之而来的旋转，基于偶极-偶极模型来表示磁力，以建立整个系统的动态模型进行数值模拟。 P-2RMNESs和其他减振器（即线性减振器和单个2RMNES）的关键结构参数通过遗传算法在不同脉冲激励水平下进行优化。根据仿真和实验结果，在相同的等效质量下，优化后的P-2RMNES在不同激励水平下表现出比对应配置更优越的性能。最后，还通过数值模拟研究了由于实验限制而影响 P-2RMNES 性能的其他因素。 这里报告的研究结果揭示了有效的并行 NES 的设计，而无需增加质量来减轻脉冲响应。