Design and analysis of plate-type eddy-current damper with high energy-dissipation capability

A plate-type eddy-current damper with high energy-dissipation capability is designed and analyzed. The damper is configured in a dimension of 270 mm × 500 mm × 80 mm by employing 16 pairs of rectangular magnets and a rectangular copper plate. The paired magnets are arranged as two rows of 4-by-4 arrays with polarities alternating along the moving direction, while the copper plate is embedded inside two rows of magnets. A finite-element model is developed to investigate eddy-current force. The damping coefficient of damper under a constant velocity of 0.2 m/s is 24.44 kN-s/m. The eddy-current force under harmonic motion can be fitted as a sum of a linear elastic force and a linear damping force. The stiffness coefficient is increased by 77 times and the damping coefficient is reduced relatively by 19%, for vibration frequency increased from 0.5 to 10.0 Hz. The sensitivity of stiffness and damping coefficients on the physical dimensions of magnet and copper plate are discussed. The phase lag is sensitive to copper-plate thickness but insensitive to clear gap between two rows of magnets. The damper is implemented on a based-isolated structure. It is shown that the damper could reduce the peak of base drift and absolute acceleration response spectra by 71.9% and 73.1%, respectively.