Abstract
This paper describes an application study of Magneto-Rheological (MR) grease damper to a structure with three stories. MR fluid is known as one of successful smart materials whose rheological properties can be varied by applied magnetic field strength, and has been applied to various kinds of device such as dampers, clutches, engine mounts, etc. However, the sedimentation of ferromagnetic particles dispersed in MR fluid may take place due to the density difference between the particles and their career fluid. In order to overcome this defect, we developed new type of controllable working fluid using grease as the career of magnetic particles which might be held in its thickener network. No or little sedimentation was observed in MR grease whose characteristics could be controlled by the applied magnetic field strength. MR grease was introduced into a cylindrical damper and its performance was studied. As a result, it was confirmed that the damping force of MR grease damper could be controlled by the applied electric current to the coil in the cylinder. Furthermore, vibration response of a three-story model structure equipped with MR grease damper was investigated experimentally, and it was shown that MR grease damper works effectively as a semi-active damper.
