Characteristics Of Magnetorheological Fluid Research Articles

Effect of Magnetic Nanoparticle Additive on Characteristics of Magnetorheological Fluid

Magnetorheological (MR) fluids, suspension of magnetic pure carbonyl iron (CI) in non magnetic carrier, were prepared with and without magnetic CI nanoparticle additive in this study. Initially, the magnetic CI nanoparticle additive was synthesized in a rather simple process of decomposition of penta carbonyl iron (Fe(CO)5) using oleyl amine and kerosene. Magnetic property and morphology of the synthesized magnetic CI nanoparticles were confirmed via vibration sample magnetometer (VSM) and transmission electron microscopy (TEM), respectively. MR fluids, prepared as a mixture of pure CI and CI nanoparticle additive of different weight ratio in carrier fluid, was investigated under different external magnetic field strengths via a rotational rheometer. Sedimentation of the MR fluid was characterized by an optical analyzer, Turbiscan. Their flow behaviors at a steady shear mode were examined with and without magnetic CI nanoparticle additive under magnetic field strength. The MR fluids with magnetic CI nanoparticles added demonstrated slightly higher yield behaviors, suggesting that pure CI and CI nanoparticle additive were being oriented in the magnetic field direction under an applied magnetic field and with much strengthened structure.

Development of a Magneto-Rheological Fluid Tension Control Device

Based on the characteristics of magneto-rheological fluid, a new type of transmission device has been developed in this paper, in which output torque can be controlled accurately by adjusting electric current. It can be applied to replace magnetic particle clutch widely used at present to achieve tension control in some small-sized winders. A structure design of prototype has been proposed. By using the Bingham plastic constitutive model, the output torque of the device has been derived. Electromagnetic finite element analysis has been employed to simulate the magnetic circuit of this magneto-rheological fluid tension control device. It is shown that this magneto-rheological fluid tension control transmission has its significant advantages comparing with traditional magnetic particle clutch. The new one can produce higher controllable torques, and may be applied widely in the future.

Study on Characteristics of Magnetorheological Fluids Based on Iron Particles and Application(Protection Cloth for Human Body)

Study on Characteristics of Magnetorheological Fluids Based on Iron Particles and Application(Protection Cloth for Human Body)

Autoregressive bispectrum characteristics of magneto-rheometer

The operating principle of measuring rheological properties of magnetorheological(MR) fluid was expounded by means of a new rheometer with double driving discs rotating at the same speed in the opposite directions. The constitutive equation of MR fluid was established with theoretical analysis from experimental data. The conventional power spectrum approach was unable to detect the existence of quadratic phase coupling for dynamic rheological measurement. Bispectrum analysis is emerging as a new powerful technique in signal processing, which can describe nonlinear coupling, restrain Gaussian noise and reserve phase component. An autoregressive(AR) model of the third order cumulant, the bispectra and bispectral contours were utilized for analyzing the dynamic characteristics of the MR rheometer by merely using the sampled output torque signals when a zero mean non-Gaussian white noise interferes with the rotary disc system. The measurement and analysis process based on virtual instruments were automatically controlled by computer in this paper. The experimental and theoretical results show that rheological properties and dynamic characteristics of MR fluid can be measured with this double disc rheometer.

Metrology of the experimental investigation of the dynamics of magnetorheological fluids

In order to verify the theoretical and experimental dependences of the dynamic characteristics of magnetorheological fluids and to determine their magnetic properties, the mean flow velocities versus the magnitude of an external magnetic field were measured. Problems of the methodology of experimental research are discussed and requirements for measurement and control apparatuses are formulated.

A two-dimensional material removal model in magnetorheological finishing

Magnetorheological Finishing (MRF) is a new advanced optics and precision mould manufacturing technology. According to the sharp rheological characteristics of magnetorheological fluid in the magnetic field, and based on earlier research, the Preston equation, the Reynolds equation and its boundary conditions are revised and extended. The material removal model in two-dimensional directions is built and analysed by simulation. Especially the influence of workpiece materials is considered. Finally, the MRF experiment is carried out, and the influence rules of the immersed depth and material kinds are studied. The experimental data are compared with the material removal model result, which confirms the mathematical model validity. The model establishment and the processing experiment will provide the important theory and experimental references for deterministic Computer Numerical Control (CNC) nanometer process of complex optics parts.

Theoretical Calculation and Testing of Damping Characteristics for Magetorheological Damper on Vehicle

From the view point of practical research and feasible structure,the establishment of an accurate mechanical model for the magnetorheological damper is one of the key factors for designing control strategy to obtain good control effect.According to various requirements of the vehicle suspension,computation and analysis of the effects of all parameters of magnetorheological damper on the damping characteristic are necessary for the design of modern vehicles.According to the requirements of vehicle damper and the principle of magnetic circuit,a magnetorheological damper of single output bar and damping hole type is designed. Based on the fluid mechanics theory and the theological characteristics of magnetorheological fluid,a theoretical calculation model for the damping force of magnetorheological damper is deduced.The characteristics of the magnetorheological damper are analyzed and calculated,and the influence of the damper structural parameters on the damping characteristics is studied.The velocity characteristics of the magetorheological damper from the experiment are adopted and the damping force-velocity curves at different current outputs are obtained.The test results are in agreement with the theoretical calculation values.The mechanical model of magnetorheological damper deduced by adopting fluid mechanics theory can provide reliable theoretical direction for the establishment of the damper control model.

A Mechanistic Model of Material Removal in Magnetorheological Finishing (MRF)

According to the sharp rheological characteristics of magnetorheological fluid in the magnetic field, the principle and mechanism of magnetorheological finishing is analyzed. Based on the Preston equation, the Reynolds equation and its boundary conditions, the two-dimensional material removal model is built and simulated. Furthermore, a series of MRF experiments are carried out, and the influence of the immersed depth and material kinds on material removal rate are clarified respectively. The experimental results are compared with the modeling results of material removal rate to confirm the mechanistic model validity.