Parameter Analysis And Application Of Eddy Current Dampers

Due to the fact that conventional oil dampers have the shortcomings such as oil spill, hard to maintain, non-linear viscous damping, additional shear stiffness and so on, we investigated a kind of plane type eddy current dampers using permanent magnets which can be applied to fields of civil engineering. This damping have many advantages such as no contact, linear viscous damping, excellent durability, convenient to erect and so on which are suitable to suppress vibration of structures in fields of civil engineering.Zhangjiajie suspension footbridge will use this kind of dampers to suppress its secondorder and third-order vibrations induced by human( frequency is 1.00 Hz and 1.39 Hz respectively). In order to design this kind of dampers, we studied its characteristics from three aspects which are theoretical, simulated and experimental, and we deduced theoretical formulation of frequency of its stiffness. Finally, we studied an entire set of methods of designing this kind of dampers. The main research contents and achievements are introduced as follows:(1) A theoretical formulation to compute the coefficient of eddy current damping was deduced based on the assumptions of uniform magnetic field and infinite plate dimension and a correction factor of magnetic field intensity was introduced in consideration of the uneven magnetic field intensity and finite plate dimension.(2) The theoretical formulation of practical magnetic flux intensity was studied, and the simulation of it have been done in order to lay the foundation of subsequent studies.(3) The simulation of plane type eddy current dampers using permanent magnets was studied, and the variation regularity of the coefficient of eddy current damping was investigated under situations like whether there is a fixed iron plate or not, different dimensions of magnetic conductive plate and electrical conductive plate, different material of electrical conductive plate, different air gap between the copper plate and the magnets, relative velocity and different magnet spacing.(4) The experiments of factors of this kind of dampers which could be controlled in simulation and in reality have been operated. And we fitted the function of coefficient of eddy current damping of the air gap between the copper plate and the magnets and discussed range of value of the correction coefficient, which could be used for the preliminary design of the dampers.(5) The design method of dampers used on Zhangjiajie suspension footbridge was studied, and we deduced the theoretical formulation and edited a program for parameters design when the stiffness element of the dampers is trapezoid cantilever. Then the whole process of designing this kind of dampers was presented, which could be used to guide analogous dampers.