Development of a Passive Type MR Damper with Variable Damping Characteristics Dependent on the Displacement and Velocity

Abstract

A novel MR damper which has the same variable damping characteristics as an existing semi-active control but no active component has been proposed and developed. The damping force changes in response to the sign of the displacement and the velocity, which is effective in reducing vibrations. Moreover, the damper has an advantage in high reliability, since the damper is composed of only passive components such as MR fluid, permanent magnets, and check valves. The prototype has been manufactured and the dynamic performance has been verified experimentally by an excitation test and a shaking table test with single-degree-of-freedom (SDOF) system. The experimental results show that the damping force changes depending on the displacement and the velocity and the damper has excellent performance in reducing the vibration of the SDOF system over a wide range of frequency. In addition, the analytical evaluation method for the damping characteristics is developed, in which the static magnetic field analysis and the algebraic equations of simplified fluid flow model are employed. Comparing the analytical results with the experimental results, it is found that the developed evaluation method can adequately simulate the characteristics of the damper.