Junji Ogawa

New magnetic viscous damper with intelligent or smart fluid for the next generation

We propose a new viscous damper using magnetically responsive fluids, whose viscous damping factor can be changed by application of a magnetic field. The used fluids are intelligent or smart fluids; MF (magnetic fluid), MR fluid (magneto-rheological fluid), and MCF (magnetic compound fluid). The damper was developed in order to avoid the sedimentation of the fluid particles and to allow the viscous damping factor to be changed by using a fluctuating magnetic field as a semi-active damper. This solves the most important problem of the previous MR fluid damper, that is, sedimentation of the particles of the fluids. We experimentally investigated the dynamic characteristics of the newly developed damper having magnetically responsive fluids. The damper is a spring and mass single-degree-of-freedom system. We dealt with the vibration in a low frequency range, less than 10Hz, for the purpose of damping in architectural applications. A comparison of the differences of the damping effects of the three kinds of the fluids, MF, MR fluid, and MCF, showed that MCF has the largest damping effect. MCF is a new intelligent fluid developed by us for the purpose of having more apparent viscosity than MF and more stable particle dispersion than MR fluid. The experimental results can be explained by the cluster of particles aggregating in the form of a chain or necklace, as observed by microscope.

Outline of Investigation and Damage

On March 11, 2011, at 2:46 pm Japan standard time, a magnitude 9.0 earthquake struck off the eastern coast of Honshu, Japan’s main island, approximately 129 km east of Sendai. The earthquake and tsunami produced severe building damage and over 15,000 people were killed due to tsunami. This earthquake was later named “The 2011 off the Pacific coast of Tohoku Earthquake” by the Japan Meteorological Agency (JMA).