Department of Electrical Engineering, Faculty of Engineering, Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashi-ku, Fukuoka 811-0295 Fukuoka, Japan. 1
The purpose of this study is to design a structure of a linear-motion type semi-active damper which can reduce the vibration caused by an earthquake. This paper proposes the more effective structure of the linear motion semi-active damper by magnetic-structure interaction analysis of finite element method using ANSYS.The semi-active damper has a simple structure that a linear mover, a magnet bar, reciprocates in coils of a stator. Nd Fe-B magnets in the magnet bar are placed so that the same magnetic poles face each other, in order to make the large change in magnetic flux in the coils of the stator. The coils are wound in opposite directions to each next coil and are connected in a series. The stator was covered with a magnetic material cover, so that the magnetic flux is extended through the cover and reduces cancellation of the flux in the coils of the stator. The motion of the mover is changed according to resistance connected to the coils. When the value of the resistance is large, the mover moves fast. On the other hand, the mover moves slowly when the value of the resistance is small. Therefore, the viscous damping coefficient of the mover can be directly changed by the value of the connected resistance. The size of the coils and the size of the magnetic material cover to produce the maximum damping force are simulated under the condition that the mover is constant. The electromotive force is calculated based on the change of the produced magnetic field according to the change of the given velocity of the mover in a short time. The damping force is calculated according to the electric current which the electromotive force applies to the connected resistance. By the simulations, more than 120 [N・s/m] of the maximum damping coefficient is acquired when the coil is wound up from 28.0[mm] of the inner diameter to 60.0 [mm] of the outer diameter.
Keywords:
Semi-active damper，Finite element method，Magnetic-structure interaction Analysis，Viscous damping coefficient.
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