振动频率对电涡流阻尼非线性行为的影响

The eddy current damper is a non-contact damping device to realize vibration attenuation with wide application prospects in the field of structural vibration control. However, the eddy current damping shows obvious vibration frequency dependency with nonlinear damping characteristics, and there are no thorough research methods to quantitatively analyze and theoretically explain the phenomenon. Therefore, taking the eddy current damper with a plate configuration as the research object, the simplified calculation method of the eddy current damping force is proposed considering the effects of the time-varying opposing magnetic field caused by eddy currents based on the distribution of the dynamic magnetic field. Moreover, the validity of the simplified method is verified by the fully coupled magnetic-mechanical finite element simulations and experiments. Compared to the traditional linear eddy current damping model based on the distribution of the static magnetic field, the simplified method is available to characterize the nonlinear changing trend of the damping force under different vibration frequencies effectively. Within 100 Hz, there is a good agreement between the calculation results by the simplified method and that by the fine finite element method with the error no more than 10%. Furthermore, the correlation between the opposing magnetic field intensity and the dynamic magnetic field phase delay both induced by motions and vibration frequency is analyzed, and then the competitive effect mechanism of them on eddy current damping is revealed. The results show that in the low frequency range, the nonlinearity of eddy current damping mainly depends on the dynamic magnetic field phase delay caused by the increase of frequency. As the frequency continues to increase, the influence of the dynamic magnetic field phase delay is gradually weakened, and the nonlinearity of eddy current damping is mainly determined by the influence of the opposing magnetic field on the static magnetic field. Finally, the conclusion provides a beneficial theoretical reference for the design of eddy current dampers in broadband vibration suppression.