Design and experimental characterization of a twin-tube MR damper for a passenger van

The smart behavior of magneto-rheological (MR) fluid is used in the present work in designing, experimentally characterizing and analyzing a MR damper for automotive application using the twin-tube damper concept. A commercially available passive damper of a passenger van was tested to find the characteristic damping requirement of the vehicle. With this as reference, a twin-tube MR damper working in valve mode was designed and fabricated. The magnetic flux density induced in the fluid flow gap is maximized using Taguchi analysis and finite element method magnetics (FEMM) software. The FEMM results are validated by verifying with results obtained analytically using electromagnetic circuit theory. The MR damper filled with commercially available MR fluid was experimentally tested in damper testing machine. The results demonstrate that the force developed by the MR damper is indeed increasing with the value of the current supplied. At various frequencies of input oscillation, the energy dissipated by the MR damper in a single cycle increases significantly with current supplied. The novelty of this work is that a twin-tube MR damper working in valve mode was designed as a replacement for the passive damper used in a passenger van. The MR damper thus developed is capable of producing practical levels of damping force at actual operating frequencies and amplitudes of the passive damper in the passenger van. For further analysis, the behavior of the MR damper is modeled by using the Bouc-Wen model for hysteretic systems. A proportional-integral-derivative controller is used to track the desired damping force in time domain to demonstrate the application of the MR damper in a semi-active suspension system.