Abstract
We deal with the resisting force of a semi-active shock absorber with magnetorheological fluid. The MR shock absorber has coils. In theory, the resisting force of the shock absorber depends on some orifices and the magnetic field of coils of the MR shock absorber adjusted by the electric current. We use two types of electromagnets made of carbon steels for machine structural use. We examine the difference of the resisting force between S25C and S45C using a drop test. As a result, it is clarified that S45C is superior for material for electromagnets of MR Shock Absorber than S25C.
