Electromagnetic Design of a Magnetorheological Damper

This study presents an electromagnetic design methodology for the magnetorheological (MR) damper. To improve the performance of the MR damper, the magnetic field should be effectively supplied to the MR fluid. Therefore, it is important that the magnetic circuit composed with the MR fluid, the ferromagnetic yoke for forming the magnetic flux path, and the electromagnetic coil are well designed from the electromagnetic viewpoint. For this purpose, two effective approaches are proposed; one is to shorten the magnetic flux path by removing the unnecessary bulk of the yoke in order to improve the static characteristic of the MR damper, and the other is to increase the magnetic reluctance of the magnetic circuit by minimizing the cross-sectional area of the yoke through which the magnetic flux passes in order to improve the dynamic and hysteretic characteristics. After designing and manufacturing two MR dampers, the conventional type and the proposed type, their performances are evaluated and compared through the magnetic field analysis and a series of basic experiments. These results show that the proposed design methodology can be effectively used as a fundamental design material for expanding application fields of the MR damper.