Fabrication and Testing of Modified Magnetorheological Damper Fitted with External Permanent Magnet Assembly

Many vehicle systems and industrial equipment face the issue of vibrations. As such, vibration control devices like classical hydraulic dampers are utilized to minimize vibrations. In this context, magenetorheological fluid is introduced as a damper fluid to improve the damper's vibration reduction capability. This damper is known as the MR damper in which the magnetic field required to activate MR fluid is produced by using an electromagnet over the piston inside the damper cylinder. However, some severe problems are observed due to internal electromagnetic piston configuration in the conventional MR damper. Therefore, modification is suggested in the damper in the form of an external permanent magnet assembly's fitment.The proposed model consists of a damper cylinder filled with MR fluid and an external assembly of permanent magnets positioned near the cylinder. The conventional and modified MR dampers have been tested on a test rig by changing the MR fluid configuration, excitation frequency of exciter, and excitation current. The MR effect on velocity and damping force in conventional and modified dampers has been recorded and compared. The results convincingly indicate that the modified MR damper delivers good performance by generating sufficient damping capacity that can be utilized for necessary applications. Importantly, it resolves the problems associated with conventional MR dampers like electric current unavailability at field, clumping, hard cake formation, remanence phenomenon, and excessive heat formation.