Development and performance tests of an eddy-current tuned mass damper with permanent magnets

To get rid of the low durability owing to easier oil leak in damping unit of classical tuned mass dampers(TMD),a novel vertical TMD employing the eddy current damping is developed and tested.The eddy-current damping has several advantages: 1) it belongs to contactless damping devices,thus there is not any friction between the damping devices and the main mass in a TMD system;2) the magnetic field is generated from the permanent magnets,thus without any external power supply;3) all the components are made with metallic materials,thus no degradation is induced.In addition,damping ratios of TMD can be easily adjusted by varying the distance between the permanent magnets and the conductive plates with no effect on stiffness parameter.Both the theoretical and experimental results show that the developed TMD has excellent damping characteristics.Moreover,the eddy-current damping ratios predicted from the simplified theoretical model fit very well with those identified from the test results when the magnetic gap is relatively small.