Optimum design of an eddy current damper considering the magnetic congregation effect

When permanent magnets are surrounded by ferromagnetic materials, the magnetic field lines are rerouted in the air gap between them, which provides an approach for the optimum design of the eddy current damper. To improve the conventional tubular eddy current damper design, an enhanced eddy current damper with a ferromagnetic shaft and a ferromagnetic layer is successfully developed in this study. It is passive, cost-efficient and reliable, significantly boosting the damping effect without occupying extra space. To explore the benefits of the ferromagnetic material, analytical models of the magnetic field distributions are derived to estimate the damping coefficient. In addition, the ferromagnetic material configuration and dimensions of the proposed eddy current damper are optimized for better vibration suppression. The experiment results agree reasonably well with the theoretical models and finite element predictions, and demonstrate the effectiveness and efficiency of this innovative design, which realizes a remarkable improvement in the damping coefficient, from 70.5 N s m−1 to 143.2 N s m−1.