Inertia Damper Using MR Fluid With Spiraled By-Pass Pipe

Authors develop a unique type damper using MR fluid in order to obtain a series inertia effect for vibration suppression. The damper consists of a cylinder, a piston, and a long by-pass pipe. A rectangular gap is spirally formed at outer side of the cylinder as like a long by-pass pipe, and covered with an outer cylinder by interference fitting. Series inertia effect is caused by quickly movement of the fluid inside the by-pass pipe, and proportional to a length, density, and a ratio of cross sectional areas between the cylinder and the by-pass pipe. It is obvious from former study that not only a resonance frequency can be shifted toward low frequency, but also vibration can be cut off at an anti-resonance frequency by series inertia effect. The test damper is manufactured, and dynamic properties are investigated when it is subjected to sinusoidal wave. Force and Displacement curves are measured, and compared with theoretical results. Seismic vibration tests using 3-story benchmark structure with the damper installed are carried out. The effect of vibration suppression is evaluated, and the validity of the inertia effect is confirmed experimentally.