Simplified damping model of the eddy current damper with a double-annular-plate configuration

The eddy current damper has plenty of advantages, such as non-contact energy dissipation, stable damping performance, and high reliability and durability, which is a novel damping device with great potential to apply in various fields. However, there are still many challenges in the applications of eddy current dampers for vibration suppression, especially in confined installation environments of aerospace structures, such as the insufficient energy dissipation efficiency of miniaturized eddy current dampers and the nonlinear characterization of eddy current damping under high frequency conditions. This study aims to propose a new design scheme for the eddy current damper to achieve high energy dissipation efficiency from lightweight and miniaturized eddy current dampers. By comparing with the composite planar configuration (which provides the highest energy dissipation efficiency in the literature) designed by Chen's group through the finite element analysis, the proposed double-annular-plate configuration achieves much better damping performance in the miniaturized version for the applications in confined installation spaces. To help the future design of the damper and uncover the underlying principle resulting in the nonlinear effect, based on the generation mechanism of eddy current damping, a simplified damping model for the double-annular-plate eddy current damper is established considering the nonlinearity of eddy current damping at high frequencies. The simplified model shows that the nonlinearity of eddy current damping mainly depends on the phase delay between the damping force and the excitation displacement. Moreover, based on the time-varying electromagnetic field theory, a mechanical-magnetic coupling finite element model is established to simulate the damping performance of the proposed damper. After validating the simplified damping model by the finite element analysis, a prototype of the double-annular-plate eddy current damper is manufactured and its dynamic behaviors and damping characteristics are measured by experiments. The results show that there is good agreement among the calculation results by the simplified model, the calculation results by the finite element analysis simulation, and the experiment results. The damping force amplitude of the double-annular-plate damper is approximately proportional to the frequency, and the delayed initial phase is slightly less than -π/2 and decreases with the increase of the frequency. The equivalent linear damping coefficient of the damper also decreases with the increase of the frequency, which shows the nonlinear effect of eddy current damping. Therefore, the proposed simplified theoretical model and the finite element model can efficiently characterize the nonlinearity of eddy current damping and can be well utilized for the mechanical and damping characteristics analysis and optimization design of eddy current dampers, which provides theoretical reference and technical support for the application of the novel damper in the aerospace field.