Papers by Keyword: Magnetorheological Fluid (MRF)

Abstract: Magnetic characteristics of three magnetic polishing fluids such as magnetic fluid (MF), magnetorheological fluid (MRF), and magnetic compound fluid (MCF) under magnetic field are experimentally investigated and analyzed. Their magnetic cluster structures under action of magnet field are observed, and their magnetic cluster models are established. Magnetic flied assisted polishing experiments for tungsten carbide are developed used these three kinds of magnetic fluids, material removal and surface roughness are respectively measured. At last, the machining characteristic of three magnetic fluids are contrasted and discussed according to experimental results.

Abstract: In order to meet the needs for the precise polishing of free-form surfaces, a new compliant polishing tool system was designed based on a magnetorheological torque servo (MRT), and integrated into a CNC milling machine. Through analysis, it was pointed out that the key factor affecting the polishing quality of this system is the stability of the system. By means of the 3D geometric modeling software ProE, the finite element analysis software ANSYS, and the dynamic simulation software ADAMS, the rigid-flexible mixed model of the system was established and the stability of the polishing pressure and tool position was numerically analyzed.

Abstract: A MRF fluid engine mount with controlled annular access, inertia track and decoupler is designed. Through the experiment it can be seen that the low frequency performance of the mount is greatly improved. Then the dynamic low frequency performance of the mount using the fuzzy PID control method of two degrees-of-freedom system in different engine speed is simulated and the results show that the fuzzy PID control method is effective to reduce the body acceleration.

Abstract: Behavior of suspended magnetic and nonmagnetic micrometer-size particles in a micro-tube filled with a magnetic fluid is investigated by using the discrete particle method based on the simplified Stokesian dynamics in order to know the polishing process of inner wall of a tube. It is shown that the chain-like clusters of magnetic particles are surrounded by clusters of nonmagnetic particles in the presence of uniform magnetic field. The clusters are held in the field direction in case of rotation of the micro-tube and in case of rotation of magnetic field.

Abstract: The apparent viscosity of magnetorheological (MR) fluids changes in the presence of a magnetic field. The stronger the magnetic field applied, the more the apparent viscosity increases. An increase in the apparent viscosity increases the restriction on the flow of MR fluids. In this study, we perform a qualitative analysis to investigate the effect of a magnetic field on MR fluids under an impact load. An experimental apparatus that consists of a drop-test tower was developed to simulate the impact load, and an MR fluid in a U-pipe was subjected to the impact load via a piston rod. In the experiment, we measured the displacement and velocity of the piston rod. On the basis of the results, the influence of a given magnetic field on the behavior of MR fluids under an impact load is discussed.

Abstract: This paper presents the preparation of magnetorheological fluids (MRF) starting from iron powder in size of 4-6 µm, silicone oil and a few commercial additives. The structure and magnetic properties of iron powder are evaluated by X-rays diffractions and hysteresis curves. The MRFs were selected through gamma radiation transmission, upon the determination of the sedimentation rate in the gravitational field. The dispersion of MRFs particles is presented using the electron transmission microscopy. The magnetorheological behavior in dynamic conditions was tested in a device specially designed for that purpose

Abstract: For a better understanding of the hydroforming process using magnetorheological fluids as a medium it is necessary to gain basic information for an analytical and numerical description of the fluid behaviour under process relevant conditions. Therefore an experimental setup is build up, which consists of a pressure chamber and a rotational symmetric outlet. Different parameters like feed rate and magnetic flux density are varied. Afterwards an analytical approach and a numerical model are developed. To get the relevant material input data for the fluid description an additional numerical simulation of the created magnetic flux density with flux lines perpendicular to the symmetry line of the outlet is performed. The leakage rates, which are observed for the experiments, are compared to the analytically calculated ones and to the results of the numerical simulation.

Abstract: In this paper, effects of critical parameters, namely initial gap, squeezing speed and applied current were statistically investigated on the mechanical behaviour of MR fluid in squeeze mode. A set of 17 experiments was designed using Design Expert 7 software to gather data from response surface methodology (RSM). The responses in terms of compression modulus were then calculated. An MRF132-DG was used as a sample in each experiment. The experiments were conducted under compression stress mode using universal testing machine (UTM). Stress-strain curves were analysed using the machine integrated TestXpert analyser software package. The stress-strain curves of MR fluid under squeeze have produced a shear thickening behaviour at 13.54 MPa of the highest stress at 0.75 of strain. A correlation between the three parameters and the stress-strain properties was specified. The results showed that the initial gap and supplied current were significantly produced a high compression modulus for the MR materials. These findings are important to enhance the capability of the squeeze MR devices to operate at its best performance. High compressive stress is crucial for most magnetorheological (MR) materials, particularly in squeeze mode devices.

Abstract: This paper attempts to use a kind of smart material-magnetorheological fluid and magnetorheological jet polishing method to polish mould. Use self-preparation MR fluid conduct experiments on MR jet polishing setup which developed by ourselves. After polished by MR jet, surface roughness of the mould improved from 812nm to 88nm. The result shows that experiment and its setup are feasible.

Abstract: In this paper, experimental study of the microwave reflection behavior in MRF was carried out. The results showed that at the same frequency the microwave reflectivity of MRF decreased with the increasing of magnetic field strength; and with the increasing of particle concentration, microwave reflectivity decreased, monotonously. Under the given magnetic field, with the increasing of microwave frequency, it first decreased, there is a lowest point at 9.2GHz, and then it increased. Usually, it is considered that the change of internal structure of MRF under external magnetic field is the main reason for the regulation behavior of microwave reflectivity.