非线性能量阱刚度优化计算与振动台试验

Stiffness optimization and shaking table tests for nonlinear energy sink

Nonlinear energy sink (NES) was proposed and its main feature to mitigate vibrations in a broad frequency band range was explored here.Firstly,the expressions for the relation between frequency and energy under 1∶1 resonance were derived using the analytical method.According to the expressions,the frequency-energy plot was drawn.This plot intuitively revealed that when a NES is attached to a linear oscillator,its vibration frequency relative to the linear oscillator has a direct relation to the energy level of the system.Then,the formulas for the relationships among the stiffness of NES and energy,frequencies and modal shapes of linear oscillators were derived with the analytical method in the model space of a multi-DOF vibration system.The optimal solution to NES stiffness was calculated with these formulas under a certain energy level of the vibration system.Based on the optimal stiffness calculation method,the NES vibration control test was designed and the corresponding shaking table tests were conducted.To test the wide frequency vibration control features of NES,a set of springs with different stiffness were employed and dynamic properties of the controlled frame were changed through adding the mass of the frame.The test results demonstrated that NES has a good broad frequency band vibration control effect,it can work well even though its stiffness deviates from the optimal value or there are some changes in dynamic features of the controlled target.