Design and modeling of a magnetic shock absorber based on eddy current damping effect

This paper describes the design, modeling, and analysis of a novel magnetic spring-damper. This cost-effective, self-powered magnetic spring-damper utilizes two permanent magnets and a conductive aluminum plate to generate both spring and variable damping effects. Eddy currents are generated in the aluminum plate due to its relative motion with respect to the magnets. These eddy currents produce a repulsive force that is proportional to the velocity of the conductor such that the moving magnet and conductor act as a viscous damper. The structure of the proposed passive magnetic spring-damper is simple, and does not require an external power supply or any other electronic device. An accurate, analytical model of the system is obtained by using the electromagnetic theory to estimate the electromagnetic forces, induced in the system. The newly developed model can be used to design high-performance dampers for various applications. To optimize the design, simulations are conducted and the design parameters are evaluated. After a magnetic spring-damper prototype is fabricated, experiments are conducted to verify the accuracy of the theoretical model. The eddy current model exhibits a 7.5% RMS error for the damping ratio estimation, and a damping ratio as high as 40 N s/m is achieved by the fabricated prototype. (c) 2008 Elsevier Ltd. All rights reserved.