We investigated the polishing effect of magnetic polishing liquid (MPL) made of abrasive particles and a newly developed magnetic responsive fluid, magnetic compound fluid (MCF) as intelligent or smart fluid. By applying steady and fluctuating magnetic fields, we investigated the polishing effects of the magnetic fields, varying the kinds of polishing material and the components of the MPL. In order to explain the cause of the experimental results, we investigated the apparent viscosity of the MCF and MPL, and used microscopic to investigate behavior of the particles in the MCF and MPL. We clarified the mechanisms governing the polishing effects through the use of a model based on the observation of the particles.
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.
We clarified the characteristics of rotating-disk and rotating-concentric-cylinder braking device types using ERF (electro-rheological fluid) with smectite particles. Concerning the steady characteristics of the both braking devices, the current density of the rotating-disk type is smaller than that of the concentric cylinder type. In addition, the input electric power per increment of torque has the same ratio as the enhancement of the shear rate. In contrast, regarding the transition characteristics, the rise time of the torque for the rotating-disk type is shorter than that for the concentric-cylinder type, though the current’s rise time is almost the same in both braking devices. It can be considered that the current density of the rotating-disk type is small and the rise time of the torque of the one type is small due to the influence of the secondary flow. The microscopic tendency of the electric charge can be guessed from the transition characteristic of the electric current.