Damping and response characteristics of passive type MR damper

The characteristics of a passive type MR damper were evaluated experimentally. The damper has variable damping characteristics as well as an existing semi-active damper, although it is fully passive device without any sensor, power supply and power controller. A prototype of the damper was manufactured in order to verify the damping and response characteristics. The excitation tests with sinusoidal displacement demonstrate that the damping force changes in response to the sign of the product of the velocity and displacement, which is analogous to one of semi-active control. The base excitation tests with a single-degree-of-freedom system show that the passive type MR damper has excellent damping effect in a wide range of frequency. In particular, the advantage is noticeable at resonance frequency. It is also shown that the base isolation system with the present damper is quite effective in a reduction of the response to earthquake excitation.