Application Of Magnetorheological Fluids Research Articles

Mulberry-like NiFe2O4 nanospheres for smart magnetic fluid: Facile synthesis, magneto-responsive performances and sedimentation stability study

Magnetorheological (MR) fluids have been extensively studied and utilized in various fields but are still restricted for their broad applications owing to the relatively poor sedimentation stability. Herein, mulberry-like NiFe2O4 nanospheres were fabricated via a facile solvothermal route to fight against the sedimentation challenge. Different analytical approaches were employed to thoroughly characterize the fabricated mulberry-like NiFe2O4 nanospheres. The resultant NiFe2O4 nanospheres were suspended in silicone oil to produce the model MR suspension and its magneto-responsive properties and sedimentation stability were investigated in detail. It was revealed that the NiFe2O4 nanospheres-based suspension demonstrated sufficient MR responses, which can be interpreted as evidence that the increased rheological and viscoelastic properties were observed as the magnetic field intensity increased. Furthermore, the designed novel MR suspension demonstrated a superior sedimentation stability in comparison with the carbonyl iron particles-based MR system, which was positive in the practical application of MR fluids to microfluidic devices.

Dimensional analysis for sedimentation behavior of magnetorheological fluids

Magnetorheological fluids (MRFs) are primarily composed of magnetic particles suspended in carrier liquids, exhibiting a remarkable capacity to respond dynamically to external magnetic fields. However, the phenomenon of solid–liquid phase separation, attributable to particle sedimentation, represents a formidable barrier to the real-world application of MRFs in engineering contexts. As a result, it becomes critically imperative to conduct a thorough investigation into the sedimentation behavior of MRFs under static conditions, to significantly enhance their practical utility. In the study, computational analysis through COMSOL was utilized to elucidate the sedimentation dynamics of MRFs. The findings indicated that particle sedimentation harbored the potential to induce localized turbulence within the flow field, thereby significantly impacting the sedimentation dynamics of MRFs. The motion of particles consistently followed a pattern where sedimentation rates decreased as the viscosity of the carrier liquids increased. Moreover, the elucidation of the settling behavior of MRFs was facilitated by the introduction of two dimensionless numbers. These dimensionless numbers were employed to systematically characterize the temporal evolution of the supernatant height throughout the settling process. This investigation further explored the intricate interdependence between these dimensionless parameters via a comprehensive series of settling experiments. The outcomes of this research uncovered a unique pattern in the solid–liquid separation process of MRFs, marked by a phase of gradual initiation, followed by acceleration, and culminating in deceleration. However, as the viscosity of the carrier liquids increased, this pattern became less pronounced, gradually shifting toward a more uniform settling trajectory.

A capacitive method and experiment for measurement of sedimentation of magnetorheological fluid

Sedimentation is one of the key issues in the practical engineering applications of magnetorheological fluids (MRFs). Testing and evaluation of the suspension stability of MRFs should be a prerequisite procedure before their applications. There are a few reported methods of measurement of sedimentation of MRFs. The opaque zone below the mudline, especially the sediment zone at the bottom in the MRF column, is the true key factor that affects the applications of MRF due to the possible irreversibility caused by the caking of the sediment zone. This study proposes a novel capacitive method on the basis of the change in dielectric constant resulting from the change in concentration of the magnetic metal particles of MRF upon sedimentation. First, an analytic model was established to present a positive correlation between the dielectric constant and volume fraction of particles throughout the entire MRF column and the theoretical expression of the dielectric constant of MRF in a test tube was obtained. Second, a capacitive sensor and the relevant experimental set-up were designed and fabricated. Especially, the effect of eccentricity error of the capacitor sensor structure on the measurement was analyzed. Then, a sedimentation experiment for prepared MRF samples was carried out, and the testing results were discussed and verified by a visual mudline observation of the supernatant zone, indicating the feasibility of testing and evaluating the suspension stability of MRF by the capacitive method.

Study on the influence of composition parameters of magnetorheological fluid on its vibration transmission characteristics

As an intelligent material, magnetorheological fluid (MRF) is used in various applications, such as vibration dampers and automotive engine mounts. In order to study the influence of MRF composition parameters on vibration transfer characteristics, this paper proposes an MRF vibration transmission equivalent model based on the analysis of the interaction between carbonyl iron particles and carrier liquid, calculates the vibration transfer power flow level difference (PLD) of MRF with different composition parameters, and performs experimental verification. The results show that when only the particle diameter changes, the PLD peak increases with increasing particle diameter, and the PLD peak frequency shifts to lower frequencies. When the particle volume fraction gradually increases, and the remaining parameters are kept constant, the PLD peak increases first and then decreases, and the peak frequency shifts to high frequencies. When changing only the carrier liquid viscosity, the PLD peak decreases as the viscosity increases, while the peak frequency is shifted toward the high frequency. The MRF has a maximum frequency shift of 61.6 Hz when the particle diameter, particle volume fraction, and carrier liquid viscosity are 8 μm, 20% and 0.3 Pa·s, respectively. It is shown that adjusting the composition parameters can change the PLD and vibration suppression band of MRF, and using this feature can help improve the broadband vibration suppression performance of MR devices and the vibration suppression efficiency under specific working conditions, further expanding the application of MRF in the field of vibration control.

Research on the application of magnetorheological fluids in artillery buffer system

Magnetorheological fluids are an important direction in the research of smart materials. Their high damping force, wide dynamic range, high frequency response and controllable stiffness characteristics make their innovative application in the field of artillery firing technology helpful in solving many technical problems faced during artillery firing. A simulation model of the dynamics of the magnetorheological buffer system is established, the material properties of the magnetorheological fluid performance parameters actively controlled by current are investigated, and a feed-forward control of the operating current in the magnetorheological buffer system is used to analyse the artillery firing recoil and vibration under different operating conditions.The results of the study show that the adoption of a feed-forward controlled magnetorheological buffer system reduces the maximum firing recoil of the artillery and the “platform effect” of the whole recoil process is obvious, which enables active control of the artillery firing process.

Characterization of magnetorheological fluids based on capillary magneto-rheometer

Magnetorheological fluids (MRFs) are a class of smart magnetic controlled materials whose rheological properties can be controlled by a magnetic field. These materials have advantages of short response time, high dynamic range and low energy consumption. Due to their excellent properties, MRFs have a widely application potential in the field of impact mitigation. As the shear rate dependent viscosity of MRFs is astonishing for the shear thinning effect, thus it is crucial to study the rheological properties cross a wide range of shear rates for guiding the design and application of MRFs based adaptive impact absorbers. Commercial rotational rheometers are usually used to test the rheological properties of MRFs, but their range of measuring shear rates are limited. Commercial capillary rheometers are designed to measure the rheological behavior over a wide range of shear rates, but they’re usually lack of ability to measure with magnetic field. In order to study the rheological properties of MRFs under higher shear rate and applied magnetic field, a lab-made speed-controlled capillary magneto-rheometer is developed in the presnt work; The expressions for equivalent shear rate and apparent viscosity of MRFs under the dimensional constraint of the set-up are derived. In addition, the theoretical expression of shear rate of MRFs is modified by Rabinowitsch correction. Then, the rheological properties of three particle volume fractions (10%, 15%, and 20%)of MRFs with different magnetic field strengths (6 mT, 13 mT, 20 mT, and 25 mT)are tested and analyzed, and the rheological characteristic curves of MRFs with shear rate range of 101s−1–105s−1 are obtained with the normalized characterization using Mason number. According to the experimental results, the MRFs show an obvious shear thinning phenomenon as shear rate increases, and in the Mason number based normalized characterization, the curves of different particle volume fractions are collapse to a master curve.

Performances of Planetary Magnetorheological Transmission Devices

Magnetorheological transmission devices (MRTDs) are a type of power transmission device using magnetorheological fluids (MRFs) as the transmission medium, which have the advantages of rapid response and continuously adjustable output performances. A new type of structure of planetary MRTDs is proposed to improve the performances of MRTDs in this study. A planetary MRTD was fabricated, and the performances of it were tested on the self-made testing system. The experimental results show that the continuously variable transmission of MRTDs under constant torque can be realized by adjusting the excitation current. The output speed or torque can be adjusted by adjusting the control current when the input speed is constant. The output torque increases with the increase in the input speed when the excitation current is constant. The performances of the MRTD were analyzed according to the properties of MRFs in complex flow and magnetic field. MRFs in complex flow and magnetic fields can produce more stable and higher responses to external magnetic fields than being simple sheared; thus, the planetary MRTDs have better performances and are useful structures for the application of MRFs in transmission.

An overview on properties and applications of magnetorheological fluids: Dampers, batteries, valves and brakes

This paper presents a review of literature that introduces the properties and applications of Magnetorheological fluids(MRFs). first, magnetic particles (iron or cobalt), base fluids(oil (mineral-synthetic) or water), and how to prepare magnetorheological fluids are discussed. Then, in the continuation of this research, considering that magnetorheological fluids are smart and soft liquids, the methods of stability and properties (viscosity, hysteresis loop, Shear yield stress, etc) Of these magnetorheological fluids are discussed. Due to the different properties of Magnetorheological fluids, the behavior of these fluids in different states is discussed. These intelligent fluids change their properties when exposed to an external magnetic field. The most important and obvious feature of magnetorheological fluids is their reversibility from liquid to semi-solid state or vice versa in the Presence or the absence of a magnetic field in a fraction of a second. This change in state and properties is known as the magnetorheological effect. This effect depends on various factors, such as the concentration of magnetic particles, the distribution of magnetic particles, the strength of the magnetic field, additives, and so on. The low magnetic effect and instability of magnetorheological fluids are the most important problems against their widespread use in modern industries. According to research, carbonyl iron particles are the most promising particles for the dispersed phase in MRF. The choice of carbonyl iron particles contributes to their high saturation magnetism, relatively low cost, low coercion, and widespread availability. Finally, according to the different properties and behaviors of these fluids, different applications of magnetorheological fluids are discussed. MRF-based control systems are increasingly used in engineering applications such as rheological magnetic electrolytes in batteries, anti-lock braking systems, magnetic clutches, vibrating dampers, shock absorbers, control valves, and various types of vibrating dampers. One of the newest applications of magnetic fluids is the magneto-rheological electrolyte. The use of MRFs in batteries introduces a new class of magnetic field-sensitive electrolytes that has the potential to increase impact resistance, safety, thermal conductivity, and energy storage in electronic devices through reversible active switching electrolyte mechanical properties.

Applying the models of magneto-rheological substances in the study of exoskeleton variable-length link with adjustable stiffness

The article considers the existing mathematical models of magneto-rheological substances and describes some of their properties. As a result of the open sources analysis, it was found that there are no exoskeleton models with variable-length links with adjustable stiffness, based on the application of magneto-rheological fluids. Therefore, the application of these fluids in other technical systems is considered. A mathematical model of an exoskeleton variable-length link with adjustable stiffness is proposed. This link can be used for supporting and strengthening the lower limbs of the human musculoskeletal system. The difference between the proposed mathematical model of the link and the existing ones lies in the fact that the section that changes its length is considered weighty. Therefore, the mathematical model of the link with a variable inertial characteristic, the moment of inertia relative to the axis perpendicular to the longitudinal axis of the link symmetry and passing through its beginning – the point where the link is fixed to the stationary mount with a cylindrical hinge, is considered. A method of motion control based on the assignment of differentiable functions is applied. The trajectory of the link movement is found, linear and angular velocities and accelerations are calculated. To showcase the link motion, the computer-animated visualization of the link motion control problem solution is presented. The control actions required for the implementation of the given motion have been calculated in the numerical experiment. The drag coefficient range of the magneto-rheological substance has been identified during the implementation of the proposed link motion. The software implementation of the proposed mathematical model of the exoskeleton variable-length link with adjustable stiffness has been done in the Wolfram Mathematica 11.3 universal computer math environment. The software package including the unit for deriving the differential equations of motion in analytical form, the kinematic trajectory synthesis unit, the computational experiment unit, and the unit for animated visualization of the model motion and its export in the wide-spread 'gif' video format has been developed.

MAGNETO-RHEOLOGICAL (MR) DAMPER – PARAMETRIC MODELLING AND EXPERIMENTAL VALIDATION FOR LORD RD 8040-1

Magneto-rheological (MR) fluid technology has significantly developed during the past decades. The application of MR fluids has proliferated in various engineering fields with the development of MR fluid-based devices, especially MR fluid dampers. MR dampers are semi-active devices used for vibration reduction in many engineering applications. The MR dampers could offer an outstanding capability in semi-active vibration control due to excellent dynamical features such as fast response, low power consumption, and simple interfaces between electronic input and mechanical output. Modelling of MR damper is crucial in describing MR damper’s behaviour. It is critical to comprehend the dynamic behaviour of these devices, as nonlinear hysteresis is a rather complex phenomenon. The Modified Bouc-Wen model represents the MR damper mathematically since this model is capable of performing as precisely as the non-parametric model. The Modified Bouc-Wen model parameters are damper dependent and must be defined for further simulation studies before utilising the damper. Validation of MR damper experimentally is one of the tasks required to confirm the parametric model performance. The specified parameters are believed to be worthwhile for this MR damper’s use in further studies of real-time semi-active (SA) suspension systems. The small values of percentage difference for force (0.5-3.5%) indicate that the parameters implemented in the Modified Bouc-Wen model accurately portray the characteristics and behaviour of the MR damper.

Enhancing Effect of Fe3O4/Nanolignocelluloses in Magnetorheological Fluid.

Magnetorheological fluid (MRF) is an intelligent material, which can be controlled by an external magnetic field. It is widely used in damping, finishing, mechanical transmission, sealing, and other engineering fields due to its magnetorheological (MR) effect. However, despite decades of research and experimental development, the wide application of MRF is still restricted by its serious settlement problem owing to the density difference between the magnetic particles and carrier liquid. Here, using the coprecipitation method, a kind of Fe3O4-modified nanolignocellulose (Fe3O4/NLC) composite fiber was characterized by its unique advantages such as low density, soft magnetism property, and high specific surface. These Fe3O4/NLCs were used as a kind of reinforcing particle with carbonyl iron powder in the new bidisperse MRF system. The performances of MRF samples were enhanced by these superior properties. We found that all MRF samples with composite fibers exhibited excellent antisettlement and dynamic mechanical characteristics and cooperativity between Fe3O4 and NLCs. Furthermore, redispersibility of MRF is qualitatively evaluated by a shearing test in this paper, explaining the high property of antihardening. This composite fiber improves the comprehensive performance of MRF and has the potential to be repeatedly used in engineering applications.

A review on multi-physics numerical modelling in different applications of magnetorheological fluids

Magnetorheological fluids involve multi-physics phenomena which are manifested by interactions between structural mechanics, electromagnetism and rheological fluid flow. In comparison with analytical models, numerical models employed for magnetorheological fluid applications are thought to be more advantageous, as they can predict more phenomena, more parameters of design, and involve fewer model assumptions. On that basis, the state-of-the-art numerical methods that investigate the multi-physics behaviour of magnetorheological fluids in different applications are reviewed in this article. Theories, characteristics, limitations and considerations employed in numerical models are discussed. Modelling of magnetic field has been found to be rather an uncomplicated affair in comparison to modelling of fluid flow field which is rather complicated. This is because, the former involves essentially one phenomenon/mechanism, whereas the latter involves a plethora of phenomena/mechanisms such as laminar versus turbulent rheological flow, incompressible versus compressible flow, and single- versus two-phase flow. Moreover, some models are shown to be still incapable of predicting the rheological nonlinear behaviour of magnetorheological fluids although they can predict the dynamic characteristics of the system.

Characterisation of Natural Oils as Carrier Fluids for Magnetorheological Fluids

The field of application of Magnetorheological fluids (MRF) is widening. The carrier fluids being used now are synthetic, expensive and non-biodegradable. Hence, there is a need for looking for better and inexpensive alternatives. This study was intended to uncloak alternatives to the synthetic carrier fluids by taking four natural oils and conducting various tests. The four natural oils, viz, Simarouba Oil, Mahua Oil, Groundnut oil, Flaxseed oil and synthetic Silicone oil were taken and tests concerning Magnetorheological fluids like density, kinematic viscosity, flash and fire point, pour point, etc., were conducted according to standards in a licensed laboratory. Based on the various tests conducted, the four natural oils have shown remarkable potential compared with commonly used silicone oil to be used as carrier fluids.

Analysis of Magneto Rheological Fluid Journal Bearing

Magneto Rheological (MR) fluids are a class of smart materials where the shear stress is not directly proportional to rate of shear. The viscosity of fluid changes as magnetic field changes and hence this phenomenon is very useful in bearing-rotor system for attenuating the vibrations. In the present study the application of MR fluid as lubricant instead of Newtonian fluid in the journal bearing is explored through steady state, dynamic characteristics and stability. MR fluid film has been modeled as per Bingham rheological model. FEM with three node triangular elements has been used to solve the Reynolds equation both for the Newtonian fluid film and MR fluid film. The results show the load carrying capacity in the case of MR fluid journal bearing is higher than that of using the Newtonian fluid. The load carrying capacity increases with the increasing magnetic field for all eccentricity ratios. The results also show better stability of the bearing using MR fluid at higher eccentricity ratios. The unbalance response of the rotor mounted on the journal bearing using MR fluid is also estimated to be lower than that of with the Newtonian fluid.

A Simulation Study on the Behavior of Magnetorheological Fluid on Herringbone-Grooved Hybrid Slot-Entry Bearing

In recent years, extensive use of smart lubricants has been made in order to control the tribological performance of fluid film bearings. The grooved surfaces of the journal bearing greatly influence the performance of bearings. In the present work, various geometric shapes of herringbone grooves (rectangular, triangular, and parabolic) with groove angles (30° and 60°) have been considered to numerically simulate the performance of slot-entry bearings. The work reported in this article deals with the numerical simulation of magnetorheological (MR) fluid–lubricated slot-entry herringbone-grooved hybrid journal bearings. Dave equation, a constitutive relation of the Bingham model, was employed to simulate the flow behavior of MR fluid. Using the finite element method (FEM), the governing Reynolds equation for a hybrid slot-entry bearing model was solved. The result shows that the use of a herringbone-grooved surface and application of MR fluid in a slot-entry bearing offers better stability and higher fluid film stiffness and minimizes frictional torque.

A Review on the Magnetorheological Fluid, Damper and Its Applications for Seismic Mitigation

Magnetorheological (MR) fluids and dampers have wide advances as smart materials because of its unique properties, notably, viscosity increases in the presence when magnetic field applied MR Fluids composed of three key components, including carrier fluid, surfactants and metal particles. The major applications of MR Fluids are in brakes, dampers, journal bearings, fluid clutches, pneumatic artificial muscles, aerospace etc. where electrical energy is converted to mechanical energy (Damping Force) in a controlled manner. Within a few milliseconds the fluid converts from liquid to semi solid state. Over the years, researchers were concerned on the ways to enhance the modelling precision. Though the proposed Dynamic models of MR Dampers represent displacement and force behaviour. In this review paper, the advances of MR Fluids, MR Damper, Damper Models, Energy harvesting and their applications for seismic resistance of structures are briefly discussed in the present study.

Controllability of magnetorheological shock absorber: I. Insights, modeling and simulation**Part of work was done while Xian-Xu ‘Frank’ Bai was a joint PhD student of Chongqing University and University of Maryland, College Park.

The smart fluids—magnetorheological (MR) fluids show the potentials for high-speed shock mitigation applications because of their fast response and large controllable damping range. In order to match the high-speed applications of MR fluids, the structural design and controllability evaluation of MR actuators are of great significance. Controllability of MR actuators are defined to be evaluated by the mechanical behaviors (i.e. damping force controllability), including the controllable damping force range, dynamic range and constant stroking load velocity range, and response time performance (i.e. real-time controllability). We proposed an internal bypass MR shock absorber (MRSA) (Bai et al 2013a IEEE Trans. Mag. 49 3422–5), which presents the possibility in vibration control and shock mitigation applications. In the internal bypass MRSA, the gap formed by the coaxially assembled inner and outer cylinders is the flow channel for MR fluids. The electromagnetic coil windings evenly wound on the outer wall of the inner cylinder and the active rings contribute to the MR effect, and continuous adjustable damping is realized through applying current into the electromagnetic coil windings. In Part I of this paper, the principle and the mechanical behaviors of the internal bypass MRSA is further in-deeply investigated via theoretical modeling and simulations. Based on the fluid dynamics—parallel plate models and the finite element analysis software ANSYS/Fluent, the mathematical model and the fluidic entities of the internal bypass MRSA are established, respectively. Response time model of the internal bypass MRSA under a voltage driver is established. The static magnetic field distributions of the internal bypass MRSA under different current excitations are obtained via ANSYS/Workbench. The response times of the internal bypass MRSA under transient impulse current excitation and transient impulse voltage excitation are obtained by transient electromagnetic simulation. The damping force performance of the conventional unicoil MRSA with an electromagnetic coil winding in positon, multicoil MRSA with five electromagnetic coil windings in positon and the internal bypass MRSA are compared and analyzed. As compared with the conventional unicoil and multicoil MRSAs with coupled structures of the piston and the electromagnetic coil windings, the internal bypass MRSA with decoupled arrangement shows much better damping force controllability. Experimental test and controllability evaluation of the internal bypass MRSA will be conducted and presented in Part II of this paper.

Application of magnetorheological fluids in the design of a leg prosthesis with active damping

The article is about of research of the behavior of magnetorheological materials (MR), later it will be implemented in a prototype leg prosthesis with active damping for people who have suffered amputations in lower extremities, which considers the use of an actuator with Magnetorheological Fluids (MRF) LORD MRF – 140 CG, whose control is based on the adjustment of the magnetic field applied to the MRF using in its design the main parameters of anatomy and biomechanics of the foot-leg system, so that the force applied in the course of the gait cycle it can be absorbed by the prosthesis, reducing the impact on the user's column thus allowing the prosthesis to be subjected to tests for emulation in different positions according to the applied load.

Thermal conductivity enhancement and sedimentation reduction of magnetorheological fluids with nano-sized Cu and Al additives

This work presents enhanced material characteristics of smart magnetorheological (MR) fluids by utilizing nano-sized metal particles. Especially, enhancement of thermal conductivity and reduction of sedimentation rate of MR fluids those are crucial properties for applications of MR fluids are focussed. In order to achieve this goal, a series of MR fluid samples are prepared using carbonyl iron particles (CIP) and hydraulic oil, and adding nano-sized particles of copper (Cu), aluminium (Al), and fumed silica (SiO2). Subsequently, the thermal conductivity is measured by the thermal property analyser and the sedimentation of MR fluids is measured using glass tubes without any excitation for a long time. The measured thermal conductivity is then compared with theoretical models such as Maxwell model at various CIP concentrations. In addition, in order to show the effectiveness of MR fluids synthesized in this work, the thermal conductivity of MRF-132DG which is commercially available is measured and compared with those of the prepared samples. It is observed that the thermal conductivity of the samples is much better than MRF-132DG showing the 148% increment with 40 vol% of the magnetic particles. It is also observed that the sedimentation rate of the prepared MR fluid samples is less than that of MRF-132DG showing 9% reduction with 40 vol% of the magnetic particles. The mixture optimized sample with high conductivity and low sedimentation was also obtained. The magnetization of the sample recorded an enhancement of 70.5% when compared to MRF-132DG. Furthermore, the shear yield stress of the sample were also increased with and without the influence of magnetic field.

Magnetorheological and Wedge Mechanism-Based Brake-by-Wire System With Self-Energizing and Self-Powered Capability by Brake Energy Harvesting

Magnetorheological (MR) fluid is a widely used smart material due to its outstanding properties. This paper presents the design, development, modeling, and prototype testing of a self-energizing and self-powered MR brake-by-wire system, whose aforementioned capabilities are enabled by brake energy harvesting. The system is composed mainly of a typical T-shaped drum-type MR brake and a wedge mechanism for self-energizing purpose. Into the system, we also install a generator that harvests regenerative energy during braking, thereby creating a self-power capability that cannot be found in common vehicular brake-by-wire systems. Brake torque analysis is conducted, and the braking process is simulated in a MATLAB/Simulink environment. Finite element analysis of the magnetic field, temperature field, and mechanical strength of critical components is carried out. The simulation results are used to optimize design parameters and material selection. Finally, prototypes and a corresponding test rig are established. The experimental results show that only about 30 W of power is required to generate a 315 N·m brake torque and that the regenerative power produced by the generator can be used for braking, thus fulfilling the self-power requirement. The investigation of different wedge angles indicates that considerable self-energizing occurs under a small wedge angle. The findings demonstrate that the brake actuator, which has a relatively small volume, can significantly enlarge brake torque while harvesting brake energy. This feature enables the promising application of MR fluids in automotive brake systems.