Evaluation of eddy current damper for vibration control of a frame structure

In this study, an eddy current damper (ECD) prototype model is presented. The ECD consists of three principal components: Neodymium Iron Boron (NdFeB) permanent magnets, a copper plate (conductive material) and an aluminium frame. The magnets have a rectangular design, and can be assembled with magnetic pole projection in either alternative or unidirectional orientations and in two orthogonal directions. The key merit of this type of ECD is its non-contact characteristic; thus there is a complete absence of mechanical friction. This study examines the use of this prototype damper when applied to suppress structural vibration in multi-storey frame structure. To effectively estimate the damping performance of the ECD, simple analytical calculations involving both infinite and finite boundaries are proposed and illustrated in this paper. These can be compared against the results of more sophisticated finite element analysis (FEA). The conductive material can be defined to move in two orthogonal directions. Therefore, based on the four magnet configurations and two directions of motion of conductive material, a total of eight models were created for analysis and validated by the proposed designed formule. It was found that analysis based on the method of images provides a satisfactory estimation of the damping force, similar to that estimated using the FE model. This study also includes experimental testing of a prototype ECD applied to suppress vibration within a six-storey aluminium frame structure. This testing shows that the prototype ECD is able to provide a significant level of damping with performance comparable to that of an ideal conventional linear viscous damper. (paper)