Nonlinear dynamic behavior research of a coupling thin beam system by designing a magnetic internal beam-type coupling nonlinear energy sink in theoretical and experimental

Elastic beam systems are usually composed of various sub-beams, which can be divided into main, secondary, and internal beams according to their importance. This research aims to use internal beams of a coupling beam system more effectively, where a magnetic-type coupling NES model that aligns more closely with engineering practices is proposed. The internal beam, combined with nonlinear connections, is defined as a novel beam-type coupling NES. The theoretical and experimental model of an elastic beam system with nonlinear connections is established and studied. Results show that the beam-type coupling NES can be realized by utilizing the internal beam combined with nonlinear connections, where the equivalent stiffness of such a system presents smoothly cubic nonlinear characteristics. The proposed beam-type coupling NES presents multiple low-order linear and nonlinear suppression modes, where the vibration of each sub-beam of the beam system is synchronously suppressed. However, under unsuitable vibration phases, the beam-type coupling NES will enter the vibration suppression failure mode. Additionally, synchronously adjusting the nonlinear stiffness of each nonlinear connection can more effectively improve the vibration suppression effect of the beam-type coupling NES. Overall, this research proposes and manufactures a magnetic beam-type coupling NES. On one hand, the magnetic beam-type coupling NES model aligns more closely with engineering practices compared with the traditional magnetic-type coupling NES. On the other hand, the design concept of the magnetic beam-type coupling NES provides a feasible way to utilize existing structures to control the overall vibration of coupled systems in engineering.