Viscosity Of Magnetorheological Fluid Research Articles

Simultaneous Thermo-Magnetorheological Response of Magnetorheological Fluids: Effect of Concentration and Composition

The rheological behavior of magnetorheological fluids (MRFs) is greatly influenced by many key parameters such as concentration, composition, temperature, and magnetic field. As magnetic particles are dispersed in a non-magnetic liquid, MRFs exhibit an increase in viscosity with increasing magnetic fields due to the formation of chain-like structures. However, this viscosity change has often been studied as a function of any one or two of the key parameters. Herein, we studied the simultaneous effect of temperature, magnetic field, concentration of dispersed phase, and MRF composition on the viscosity of MRFs. Understanding the simultaneous effect of tunable parameters such as temperature and magnetic field allows for optimization of MRF performance and enhanced viscosity in commercial applications. Rheological experiments were performed on MRFs over a wide range of temperatures (15–65 °C) under magnetic fields between 0.1 and 1 T. The thermo-magnetorheological response was also studied with varying magnetic particle concentration (1 vol%–25 vol%) and MRF composition (both dispersed phase and carrier liquid). The results demonstrated a strong influence of magnetic particle composition and concentration on the MRF viscosity along with temperature while the carrier liquid composition had relatively negligible influence.

An experimental and artificial neural network investigation on the laminar flow of magnetorheological fluids through circular pipes

Fluids can change their physical properties when they are exposed to magnetic fields. Magnetorheological (MR) fluids are classified as smart materials because their viscoelastic properties can increase by the application of the magnetic field. Accordingly, they are used in different engineering applications such as flow control and vibration damping. In this study, three different types of MR fluids flow in circular pipes with diameters of 10 and 15 mm and length of 300 mm were experimentally investigated with and without applying the magnetic field. An electromagnetic device was designed and manufactured in order to create a magnetic field induction for experiments. Throughout the experiments, the range of magnetic field induction value was B = 0–0.15 T, increased to 0.01 T. Based on the results obtained by the experimental study, it can be asserted that applying the magnetic field prompted an increase in the viscosity of MR fluids, leading to decreasing flow velocity. At B = 0.15 T, which is the highest value of the magnetic field, the flow velocity values dropped by 95%. Subsequently, the artificial neural networks algorithms are used in accordance with the obtained results to develop a correlation that clarifies the effect of the magnetic field on the flow velocity. The results show that the experimental and ANN models perform very similarly, and the ANN algorithm yields better results as a tool to predict the MR fluid flow behavior.

Design, validation, and application of a hybrid shape memory alloy-magnetorheological fluid-based core bracing system under tension and compression

Civil infrastructures are vulnerable to catastrophic failures when exceeding the limit loading, requiring a reliable structural control mechanism, such as bracing systems, to enhance the integrity and stability of the structure. Bracing systems improve the performance of the structures by increasing the stiffness/strength of structures, the damping coefficient, and/or the energy absorption capacity. However, the functionality of these bracing systems is not controllable and may be altered after strong seismic events. Recently, the smart bracing systems based on multifunctional materials, particularly the shape memory alloy (SMA) and the magnetorheological fluid (MRF) have been developed. The superelasticity properties of SMA give the capability of recovering the original state after remarkable deformation. Furthermore, the SMA dissipates the energy of the applied load in the loading-unloading mechanism. The viscosity of MRF is variable and depends on the intensity of the applied magnetic fields. In the present study, a state-of-art hybrid SMA-MRF-based core bracing system is designed and in-house fabricated to enhance the structural behavior of the bracing system, including energy dissipation capacity and equivalent damping coefficient. Experimental tests have been conducted to illustrate the functionality of the system and the benefits of the SMA and the MRF systems. Finally, the seismic performance of the three-, six- and nine-story buildings equipped with the proposed SMA-MRF damping system is numerically assessed using nonlinear response history analyses. The results reveal that the proposed damping system significantly improves the seismic performance of the archetype buildings.

Enhancement effect of nonferromagnetic particles on the viscosity of magnetorheological fluid under a dynamic magnetic field

This study aims to investigate the effect of nonferromagnetic particle content on the properties of the magnetorheological fluid (MRF) under a dynamic magnetic field. A magnetic-induced viscosity calculation model under the temperature field was built. The influence on the viscosity of the MRF made in-house was analyzed by adding different proportions of nonferromagnetic particles, such as glass powder. Experiments show that a certain proportion of glass powder can increase the viscosity of the MRF. When the powder content is less than 10%, viscosity increases as the glass powder content increases. Conversely, viscosity decreases as the glass powder content increases when the content is more than 10% but less than 20%. These results indicate that adding micron glass powder to the MRF can increase the magnetic saturation limit of the MRF under the dynamic magnetic field and improve its settlement resistance by 25.6%.When 10% glass powder is added to the MRF containing 60% iron powder, sedimentation resistance increases by 25.6%. When the magnetic field intensity is 640 mT, the viscosity of the MRF increases by 6.6 times.

The heat flow coupling effect of laser-assisted magnetorheological polishing

During the magnetorheological polishing process of concave workpieces, the magnetorheological fluid tends to accumulate at the entrance of the polishing zone, resulting in a decrease in the polishing efficiency and quality. To solve this problem, in this paper, laser-assisted magnetorheological polishing technology was proposed. Based on the theory of fluid mechanics and heat transfer, a three-dimensional temperature field distribution model of the spherical polishing film was established to achieve local temperature control at the entrance of the polishing zone. Then, the functional relationship between the viscosity of the magnetorheological fluid and the temperature was obtained experimentally. On this basis, the shear force and hydrodynamic pressure models of the polishing zone were established, which reveal that the heat flow coupling effect can increase temperature at the inlet of the polishing zone and reduce the viscosity of the local magnetorheological fluid, thereby reducing the shear stress in the polishing zone. The results show that when the laser power is 3 W and the magnetorheological fluid flow rate is 6 ml/s, the viscosity of the magnetorheological fluid at the entrance can be effectively reduced, and the shear force in the polishing zone decreases slightly.

Frequency Method of Measuring the Viscosity of Magnetorheological Fluids in a Rotary Viscosimeter

A frequency method of measuring the dynamic viscosity of rheological media is outlined for the example of a magnetorheological fluid. The method is based on the operational principle of a rotary viscosimeter, in which the torsion angle depends on the characteristics of the viscoelastic medium.

Multi-objective optimization of magneto-rheological mount structure based on vehicle vibration control

Considering the influence of mount structure parameters on the quality of vehicle noise, vibration and harshness (NVH), a multi-objective optimization method of the magneto-rheological (MR) mount based on vehicle vibration control was proposed. A lumped parameter model was used to establish the relationship between the structure parameters of the MR mount and the NVH performance of the vehicle. Considering the influence of current on the magneto-rheological fluid viscosity and flow rate in damping channel, the dynamic characteristics of MR mount was obtained by the lumped parameter model. Then, a 10 degrees of freedom (DOF) vehicle model with MR mounting system was established. Finally, a co-simulation optimal platform was developed by the ISIGHT, MATLAB, and ANSYS software, and the non-dominated sorting genetic algorithm II was used to optimize the design of the mount magnetic circuit with the goal of improving the quality of vehicle NVH. The results showed that under the start/stop and the constant speed conditions, the root mean square values of vibration acceleration of the driver’s seat rail of the vehicle with the optimal design magneto-rheological mount decreases by 31.6% and 7.8%, respectively compared with the initial design mount, improved the ride comfort of the vehicle.

Metrological characteristics of the frequency method for measuring the viscosity of magnetorheological fluids in a rotary viscometer

A frequency method for measuring the dynamic viscosity of rheological media is described using the example of a magnetorheological fluid. The method is based on the principle of operation of a rotary viscometer, in which the torsion angle depends on the characteristics of the viscoelastic medium. Keywords frequency method, dynamic viscosity, torque, beat signal, methodical error, resolution, accuracy, twist angle, torsion. gord349@mail.ru; oxulkovs@mail.ru

Effect of Hard Magnetic CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles Additives on Improving Rheological Properties and Dispersion Stability of Magnetorheological Fluids

Increasing dispersion stability is the main issue in recent research at magnetorheological (MR) fluids. The presentation of nanoparticle addictive in MR fluids is an effective method not only to increase dispersion stability but also increasing performance in MR fluids. In this study, the effect of hard magnetic CoFe2O4 nanoparticles addition on rheological properties and dispersion stabilization had been studied. Rheological properties were investigated using a rheometer at room temperature. The result showed that the addition of CoFe2O4 nanoparticles 1wt% in particles of MR fluids were improving the shear stress and viscosity of MR fluids. Both MR fluids with and without nanoadditives behaving like a Newtonian fluid at the off-state condition and act like Bingham fluid at the on-state condition. Moreover, MR fluid with CoFe2O4 additives had a higher sedimentation ratio than MR fluids without additives.

Optimal design and experimental evaluation of magneto-rheological mount applied to start/stop mode of vehicle powertrain

Magneto-rheological mount is one of the most effective vibration isolation devices for the vibration isolation system of vehicle powertrain. In this article, a flow type of magneto-rheological mount was proposed to control the vibration and the torque excitation of the engine when vehicle was in start/stop mode. A mathematical model for the flow type of magneto-rheological mount was formulated with consideration of the influence of current on magneto-rheological fluid viscosity and the relationship between liquid resistance effect and flow rate in damping gap. Then, a co-simulation optimal platform was developed by the Isight and the ANSYS, and the non-dominated sorting genetic algorithm II was used to optimize magnetic circuit. Subsequently, two prototypes of magneto-rheological mounts were manufactured according to the initial design and the optimal design model, and the dynamic performance test of magneto-rheological mount monomer and the vibration isolation performance test of the whole vehicle under start/stop mode were carried out, respectively. The experimental results showed that the controllability and the vibration isolation performance of the optimal design magneto-rheological mount were significantly improved compared with the initial design.

Research on Theoretical Modeling and Parameter Sensitivity of a Single-Rod Double-Cylinder and Double-Coil Magnetorheological Damper

For the single-rod double-cylinder and double-coil magnetorheological (MR) damper studied in this paper, the damping force model of the damper is established by adopting multidisciplinary domain modeling method bond graph theory. Firstly, combined with the structure of the MR damper, the bond graph model of the MR damper was established, the damping force model of the damper was derived through the bond graph theory, and the influence factors, such as the displacement, velocity, and acceleration of the damper were considered in the model. Based on the simulation of force-displacement and force-velocity characteristics of the damping force carried out by the damper theoretical model under different currents and velocities as well as the comparison with the damper bench test results, it was found that the force-displacement and force-velocity characteristic experiment curves of the damper agreed well with the simulation results. Under different working conditions, the maximum error of damping force of the MR damper was 7.2%. The damping force model of the MR damper studied in this paper was compared with that of the damper without considering the inertia force of MR fluid, and the influence of the inertia force of MR fluid on the damping force of the MR damper was analyzed. The results show that when the frequency of the damper is large, the inertial force of MR fluid has an important influence on the damping force; therefore, considering the inertial force of MR fluid in the model can greatly improve the accuracy of the model. The influence degree of key parameters on the damping force of the MR damper was studied through the theoretical model; such key parameters ranging from large to small were the channel clearance, energizing current, piston diameter, motion velocity, channel length, zero-field viscosity of MR fluid, and nitrogen pressure. This provides a basis for the adjustment of the damping force of the MR damper.

Predicting the Material Removal Rate (MRR) in surface Magnetorheological Finishing (MRF) based on the synergistic effect of pressure and shear stress

Although the pressure and shear stress are motivations of the material removal of optical component surface in magnetorheological finishing, pressure is often ignored as the shear stress is the dominant factor in the removal rate prediction. To develop a more precise prediction removal function model, the role of pressure should be considered. Herein, a material removal rate (MRR) model involving the pressure and shear stress is proposed. Experiments were carried out to verify the validity of the MRR model under various process parameters, including the immersion depth, viscosity of magnetorheological fluid, and rotational speed of the polishing wheel. The pressure is shown to be indispensable in predicting the peak and volumetric removal rate. In addition, the MRR model including pressure allows for a better agreement of the removal function topography in comparison with the only shear stress-induced material removal model. This work fills in gaps relating to fundamental MRF mechanisms and provides a new perspective for the study of material removal behaviors of MRF on optics.

Contribution of magnetic nanoparticle in thermal conductivity of flake-shaped iron particles based magnetorheological (MR) fluid

Magnetorheological (MR) fluids were prepared in transformer oil as well as transformer oil based magnetic fluid having 2 wt. % of Fe3O4 particles. The thermal conductivity enhancement (w.r.t. carrier) in the case of transformer oil based MR fluid under a field was found to vary from 219%, 304%, and 356%, respectively, from 15 vol. %, 20 vol. %, and 25 vol. % of iron concentration. These values are much higher than that obtained for spherical-shaped iron particles based MR fluids. This is further enhanced by another 30% at the same magnetic field when the same flakes were dispersed in transformer oil based magnetic fluid. In addition, the magnetic fluid based MR fluids exhibit minimum hysteresis in thermal conductivity when the field is removed. The increase in the thermal conductivity of transformer oil based MR fluid is due to the shape effect as well as the reduction in thermal resistance due to a higher particle-particle interaction compared to spherical particles. In addition, on adding nanoparticles, the friction between the particles reduces and nanoparticles facilitate flake-shaped particles to form a stronger chain. This results in an enhancement in thermal conductivity. The observed reduction in the viscosity of MR fluids with nanoparticles supports the concept of the increased orientation of flakes in the direction of the field.

Torque on a Shaft Connected to the Driveshaft by a Magnetorheological Coupling

New approaches to measuring the viscosity of magnetorheological fluids in two or more shafts in the presence of a magnetic field are considered. These approaches are based on torque measurement. It proves expedient to replace all the choke channels in magnetorheological transformers by a single channel between coaxial cylinders.

Parametric Analysis of Magnetorheological Strut for Semiactive Suspension System Using Taguchi Method

Magnetorheological (MR) strut is among the leading advanced applications of semi-active suspension systems. The damping force of MR damper is controlled by varying the viscosity of MR fluid. In this work, the viscosity of MR damper varies by changing the current from 0.5A to 0.7A. The design of experiments is taken into account in concert with the product/process development as one completely advanced tool. The parameters used for ride comfort optimization are sprung mass, spring stiffness, tire pressure, current, and cylinder material with two levels of each. Taguchi orthogonal array method is used to select the best results by parameter optimization with a minimum number of test runs. In this paper, from Taguchi L16 array and S/N ratio analysis, it is observed that the cylinder material with Al and CS for damper cylinder is a key parameter for performance measure of semi-active suspension system. From regression analysis, a linear mathematical model is developed for Al and CS as cylinder materials. The interaction of cylinder materials with all four parameters is plotted. The methodology implemented for measurement of acceleration as a ride comfort is as per IS 2631-1997. The more economical model of magnetorheological damper will motivate Indian auto industry to broader applications.

One-way sound propagation via spatio-temporal modulation of magnetorheological fluid.

This manuscript details the possibility of achieving one-way sound propagation using a smart fluid such as magnetorheological fluid (MRF) by subjecting it to a spatio-temporally varying magnetic field. The local speed of sound in MRF is dependent on applied magnetic field as demonstrated in several experimental works and this property of MRF has been leveraged, in this work, to induce one-way bandgaps. Initially, a general wave equation pertaining to fluid with space-and-time-varying material properties was derived. Assuming plane wave propagation in one dimension, an approximate Floquet solution was imposed and the dispersion relationship was obtained. A comprehensive finite element analysis was conducted and good agreement was noted between the numerical and theoretical dispersion relations. It was concluded that space-time periodic modulation of fluid density and local sound speed is necessary to induce asymmetry in the band diagram around the ω axis. The feasibility of real-world implementation using MRF has been discussed. A parametric study detailing the effect of viscosity on the one-way bandgaps has been undertaken. It was found that one-way bandgaps formed at relatively lower frequencies are more robust to viscous corruption. A real-world implementation may be feasible if the viscosity of MRF is less than 3000 Pa-s.

Design of magneto-rheological brake for optimum dimension

Online control of braking performance of magneto-rheological (MR) brake by bridling the apparent viscosity of MR fluid and by amending magnetic field is considered as an effective and smart option to replace the conventional disc brake. The magnetic field procreated by electromagnet in MR brake is reliant on dimensions and material properties of MR brake (casing, rotor and MR fluid region). Extensive works have been reported on enhancing the magnetic properties of MR fluid to achieve maximum braking performance; however, scarce works are available that reflects that the dimensions of MR brake influence the braking performance. Prior works on MR brakes focus on designing for meticulous outer dimensions of brakes, and thus, their results find little utility to a new designer. Therefore, the objective of the present work is to propose a methodology to determine the dimension of MR brake for a given outer dimensions, which shall provide maximum braking performance. The, braking performance is evaluated by assessing the effective torque and brake density. Magneto-static analysis using ANSYS is employed for determining the magnetic field in the MR region, and thereafter, the braking torque is calculated. From the obtained results, curve fit equations are proposed to estimate the values of (i) MR brake casing thickness, (ii) height of the MR brake to rotor, (iii) thickness of core, and (iv) thickness of MR fluid region, for achieving maximum torque. To validate the proposed methodology, MR brake with two different electromagnets and rotors is developed. The static performance of MR brake is evaluated by measuring the braking torque for different currents using a torque wrench and the dynamic performance of the MR brakes is performed on an MR brake test setup. The dynamic performance is evaluated by measuring viscous torque. Finally, the comparisons of the theoretical and experimental results are performed and the obtained results are presented.

Design and Evaluation of a Semi-Active Magneto-rheological Mount for a Wheel Loader Cabin

In this study, a semi-active magneto-rheological (MR) mount is designed and manufactured to minimize unwanted vibrations for the cabin of heavy vehicles. Normally, working conditions in heavy vehicles are extremely rugged. Usually, the heavy vehicles use passive rubber mounts for the reduction of vibrations from road. However, the passive mount has definite performance limitations because the passive mount has a fixed resonance frequency when the design is finished. An MR application is one of the solutions because the viscosity of MR fluid can be controlled. As a first step, an experimental apparatus was established for performance evaluation of the mounts. The apparatus has hydraulic excitatory, force, and displacement sensors. Performance of two different passive mounts used in industrial fields were evaluated. The passive mount data of force-displacement, force-velocity, and displacement transmissibility were collected and tested. After that, an MR mount was designed and manufactured that provides better performance using the passive mount data. The MR mount uses two different flow paths, annular duct and radial channels, for generating the required damping force. The field-dependent damping forces were then evaluated with respect to the moving stroke and input current. In this work, in order to control the damping force, an on-off controller associated with the fast Fourier transform (FFT) was used. The control results of the MR mount were compared with the results of passive rubber mounts. It was shown that the semi-active MR mount can attenuate vibrations more effectively at all frequency ranges compared with the passive rubber mount.

Design and performance evaluation of a haptic interface based on MR fluids for endovascular tele-surgery

In this paper, a magnetorheological (MR) fluids based haptic interface has been developed in master site to provide the haptic sensation to the interventionalist during endovascular tele-surgery. The novel design of haptic interface allows the interventionalist to apply conventional axial and radial motions to a rigid catheter which goes through the MR fluids. In addition, the haptic feedback in the axial direction can be generated by altered the viscosity of MR fluids. The actual force measurement is provided to assess the effectiveness of this haptic feedback. While to evaluate the performance of this master device, the virtual-reality (VR) simulator is as the slave side to execute the replicated motions, pull, push and twist of the virtual catheter, which is applied by interventionalist in master site. The ten operators are recruited to navigate a catheter through virtual cerebral-vessel. Experimental results indicate that the use of the proposed haptic interface has a benefit to avoiding the collision and improving the safety of endovascular tele-surgery.

Magnetic effect in viscosity of magnetorheological fluids

In this work the study of viscosity is presented for a magnetorheological fluid made from iron oxides micrometre, under an external magnetic field. The material was characterized by magnetic loops in a vibrating sample magnetometer and its crystal structure by X-ray diffraction. The results show that saturation magnetization and coercive field have dependence with the powder size. The material has different crystal structure which lattice parameters were determined by Rietveld refinement. The viscosity of the magnetorheological fluid was measured by a viscometer with rotational symmetry with and without external field. This result evidence a dependency on the size, percentage iron oxide and the applied magnetic field, it is due to the hydrodynamic volume of iron oxide interacts with the external magnetic field, increasing the flow resistance.