As one of the semi-active vibration control devices for mechanical or civil structures, magneto-rheological fluid dampers have been enthusiastically studied and developed since the 1990s. A new magneto-rheological material for such dampers has been developed to provide a practical solution to the significant common drawback of sedimentation of ferromagnetic fine particles in the fluid. Industrial grease is used as the dispersion medium in this material. The thickener to be added in the grease to control the rheological properties seems to prevent separation of the particles from the dispersion medium. Several performance tests were carried out with a proto-type of the damper with the newly developed magneto-rheological grease, namely, the magneto-rheological grease damper. Based on the test results, the energy dissipation capabilities of the damper and the basic characteristics of the magneto-rheological grease were verified to provide semi-active vibration control. Moreover, the analytically-derived design formulae for the damper were improved on the basis of the test results.
Semi-active vibration control of horizontal seat suspension by using magneto-rheological damper
