Stable and Efficient Vibration Suppression of a Coupled Beam System via Series-Coupled Nonlinear Energy Sinks

Coupling beam systems are common simplified models for complex engineering structures prone to vibration. While Nonlinear Energy Sinks (NESs) are effective for vibration suppression, their application to coupled structures can induce undesirable complex responses, compromising system stability. To address this issue, this paper proposes a novel series-coupled NES configuration, where NES units on different substructures are nonlinearly connected. A theoretical model of a coupling beam system equipped with multiple series-coupled NESs is established, and its dynamic responses are predicted using the Lagrange method. The results demonstrate that the series-coupled NES effectively suppresses vibration across multiple resonance regions while avoiding the quasi-periodic responses often generated by traditional, uncoupled NESs, thereby enhancing system stability. The performance is sensitive to key parameters such as the essential and connecting nonlinear stiffness, which must be carefully selected. Furthermore, a distributed design scheme with multiple series-coupled NESs is shown to significantly improve suppression efficiency without requiring remanufacturing. This study reveals that the most effective suppression from a global perspective can be achieved by optimizing the locations of the NESs. Overall, the proposed series-coupled NES presents a promising strategy for achieving high-efficiency and stable vibration control in coupled engineering structures.