The application of multi-degree of freedom nonlinear energy sinks (MDOF-NES) to control the vortex-induced vibrations of a sprung cylinder passively is investigated in this paper. The flow-induced loads on the cylinder are modeled by the wake Van der Pol oscillator. The MDOF-NES consists of three oscillators connected in series, where the first mass is linked to the cylinder structure by a linear spring. The second mass is connected with the first and third masses by pure cubic springs and linear viscous dampers. The cylinder-MDOF-NES assemble model is analyzed in two scenarios involving lower and strong linear stiffness couplings. Numerical investigations of the bifurcation and limit cycle oscillation (LCO) behavior associated with parametric changes are performed. An appropriate design of the MDOF-NES parameters allows mitigating the sub-critical behavior and control LCO amplitudes. The MDOF-NES approach based on the lower linear stiffness coupling has shown to be more effective in controlling the LCO amplitudes. Moreover, it is verified that the MDOF-NES masses have a significant effect on the LCO stability, amplitudes, and synchronization frequency range. Comparison between the MDOF-NES and a classical Type I NES was also performed to ensure the superiority of the MDOF-NES in suppressing the vortex-induced oscillations.

本文研究了多自由度非线性能量汇（MDOF-NES）在被动控制弹簧圆柱体涡激振动中的应用。圆柱体上的流动引起的载荷由尾流范德波尔振荡器建模。MDOF-NES 由三个串联的振荡器组成，其中第一个质量通过线性弹簧连接到圆柱体结构。第二个质量块通过纯立方弹簧和线性粘性阻尼器与第一和第三个质量块连接。圆柱体-MDOF-NES 装配模型在涉及较低和强线性刚度联轴器的两种情况下进行分析。对与参数变化相关的分岔和极限循环振荡 (LCO) 行为进行了数值研究。MDOF-NES 参数的适当设计允许减轻次临界行为并控制 LCO 幅度。基于较低线性刚度耦合的 MDOF-NES 方法已显示在控制 LCO 幅度方面更有效。此外，已证实 MDOF-NES 质量对 LCO 稳定性、幅度和同步频率范围有显着影响。MDOF-NES 与经典型的比较还进行了I NES 以确保 MDOF-NES 在抑制涡流引起的振荡方面的优越性。