Types Of Magnetorheological Fluid Research Articles

Simplified inverse dynamics models for MR fluid dampers

The magnetorheological (MR) damper is considered to be one of the most promising semi-active control devices for reduction of structural vibration. Due to the damper’s nonlinear characteristics, its inverse dynamics model is difficult to obtain. In this paper, a simplified approach, namely the simplified inverse dynamics (SID) model, has been developed for both the Bingham plasticity model and the Bouc–Wen hysteresis model. SID models have then been used to calculate the optimal fluid yield stress or input current, in order to realize the desirable control forces obtained from various optimal control algorithms. For each model, a piston velocity feedback (PVF) algorithm and a damper force feedback (DFF) algorithm have been formulated. The proposed model has been shown to be applicable to both small-scale and large-scale MR dampers. Also, different configurations of MR dampers, such as ones with different dimensions, coil resistances, types of MR fluid, have been employed to show the generic nature of the SID model. The effectiveness of force tracking using the SID model has been demonstrated through a series of numerical simulations. A multi-storey frame structure with MR damper–brace systems, using a large-scale 20-ton MR damper, has been adopted. Numerical results show that the MR damper with the proposed SID model can produce forces very close to the optimal control forces, and that the response reduction is very close to that for the case of fully active control. Also, equally high accuracy of force tracking for different shaking levels and frequency contents of ground motions can be observed. The results demonstrate that the SID model can be a simple, yet effective, tool for both research and application purposes.

20502 MR流体の基本特性の測定とMRデバイスの設計(OS7 知能流体・構造システム)

Working modes of shear deformation and pressure flow typically appear in devices using Magnetorheological (MR) fluids. In this paper, rheometers, which can apply shear deformation and pressure flow respectively, have been developed. As typical characteristics of MR fluids, shear stress and pressure difference have been measured on changing flow rate, magnetic flux density, types of MR fluids, and gap length through which MR fluids flow in MR devices. Considering the magnetic circuit in these rheometers, relationship between magnetic flux density and magnetic field strength of an MR fluid has been shown. Using these results, designing method of MR devices has been shown.

Measurements of Typical Characteristics of MR Fluids and Their Application to Design of MR Devices Considering Working Modes

Magnetorheological (MR) fluids can vary the rheological characteristics according to applied magnetic field strength and have been applied to various kinds of devices such as dampers, cluches, etc. In this paper, typical characteristics of MR fluids were measured under two types of working modes, shear mode and pressure mode, which typically appear in MR devices. Shear stress in shear mode and pressure difference in pressure mode were measured on changing flow rate, magnetic flux density, types of MR fluids and gap through which MR fluids flowed in MR devices. Using the experimental result, the force generated by MR devices was modeled to each mode. As a result, it was shown that MR devices could be designed in respect of the gap and magnetomotive force of the magnetic coil in the devices on the condition that the maximum controllable force of MR devices was given.

せん断変形および圧力流れに対するMR流体の基本特性(OS.4 機能性流体と先端融合化)

Working modes of shear deformation and pressure flow typically appear in devices using Magnetorheological (MR) fluids. In this paper, rheometers, which can apply shear deformation and pressure flow respectively, have been developed. As typical characteristics of MR fluids, shear stress and pressure difference have been measured on changing flow rate, magnetic flux density, types of MR fluids, and gap length through which MR fluids flow in MR devices. Considering the magnetic circuit in these rheometers, relationship between magnetic flux density and magnetic field strength of an MR fluid has been shown. Using these results, designing method of MR devices has been shown.

Behaviour of MR fluids in squeeze mode

The behaviour of three types of magnetorheological fluids under squeeze mode was investigated. A special device was designed and fabricated to perform these experiments which were carried out on an Instron Multiaxial Testing Machine. The hysteresis loops of the MR fluids were studied for different intensities of magnetic field, frequency, strain amplitude and angular amplitude. The results showed that the damping force and the area of the hysteresis loop of MR fluids increase with the magnetic field (or electric current i) and displacement amplitude (x0). Changes to the frequency (f) produced different behaviour of the various MR fluids. The peak compressive force was found to increase with the increase in number of cycles (N).