Eddy Current Damping in Structures

Abstract

When a conductive material is subjected to a time-varying magnetic flux, eddy currents are generated in the conductor. These eddy currents circulate inside the conductor generating a magnetic field of opposite polarity as the applied magnetic field. The interaction of the two magnetic fields causes a force that resists the change in magnetic flux. However, due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat and the force will die out. As the eddy currents are dissipated, energy is removed from the system, thus producing a damping effect. There are several different methods of inducing a time-varying magnetic field, and from each method arises the potential for a different type of damping system. Therefore, the research into eddy current and magnetic damping mechanisms has led to a diverse range of dampers, many of which are detailed in this paper. The majority of the research in eddy current damping has taken place in the area of magnetic braking. A second topic that has received significant interest is the use of eddy current dampers for the suppression of structural vibrations. However, much of this research is not concentrated in one area, but has been applied to a variety of different structural systems in a number of distinct ways. In this paper, we review the research into various types of eddy current damping mechanisms and we discuss the future of eddy currents with some potential uses that have not yet been studied.

General 2-D Transient Eddy Current Force Equations for a Magnetic Source Moving Above a Conductive Plate

“…The results present in this paper will be useful for gaining a deeper understanding of the transient effects encountered in eddy current damping [21], braking [22], and maglev transportation [19,23,24] as well as for Lorentz force eddy current non-destructive testing [25] applications.…”

Vibration Suppression of a Cantilever Plate Using Magnetically Multimode Tuned Mass Dampers

“…Sodano and Bae [9] and Bae et al [10,11] have already presented a good literature review. Kwak et al [12] introduced an eddy current damper (ECD) and applied it to the vibration suppression of a cantilever beam.…”

Design and Damping Analysis of a New Eddy Current Damper for Aerospace Applications

“…Since it is rather difficult to implement maintenance and the operational environment is severe in aerospace, the damping device should be advanced in long function fatigue life, high reliability, and good applicability in vacuum and heat transformation conditions. Eddy current dampers (ECDs), with instinct natures such as Engineering, Beihang University, PR China non-contact, non-leakage and easy implementation, become a candidate to suppress vibrations of a system for aerospace applications (Sodano and Bae, 2004).…”

“…In his research, the dynamic behavior of the ECD is analyzed and it is found that the force/velocity ratio of the damper significantly varies with temperature. Sodano and Bae (2004) review various types of eddy current damping mechanisms used in different structures and systems, including the applications utilized in space field. In addition, the future of eddy current dampers with some potential uses that have not yet been studied is discussed in his article.…”