Performance of Magnetorheological Fluids in a Novel Damper with Excellent Fail-safe Behavior

A novel magnetorheological (MR) damper, whose magnetic circuit contains two permanent magnets apart from an electromagnet, is described and tested. Without any consumption of electric energy, a medium damping force is achieved, which ensures an excellent fail-safe behavior in case of an electric power loss. This medium damping force can be increased or decreased, depending on the polarity of the current in the coil. The influence of the composition of the MR fluid in terms of the concentration of iron particles between 20 and 50 vol.% on the damping force and frequency dependency could be evaluated. Finally, the damping force after various storage times of the damper was studied and indicated a good redispersibility of the MR fluid.