Use Of Magnetorheological Fluids Research Articles

Magnetorheological fluids: A comprehensive review

The magnetorheological (MR) fluids contain magnetic micro-sized iron particles, non-magnetic-based fluid, and some additives in order to mitigate sedimentation and agglomeration. The various carrier fluids used in the preparation of MR fluids are mineral oil, silicon oil, castor oil, soybean oil, kerosene, synthetic oils, honge oil, organic oil, water-based oils, etc. However, for obtaining better vibration control, silicone oil is the most preferred one due to its higher viscosity index, lower friction characteristics, higher flash point, and higher shear strength. The MR fluids have various application areas such as dampers, prosthetic knees, valves, brakes, clutches, finishing processes etc. The dampers containing MR fluids are used in automobile cushioning for enhancing passenger comfort and MR suspensions significantly improve steering stability in vehicles. In case of MR brakes, the braking torque on the rotating disks is controlled using the generated shear stress. The carbonyl iron (CI) particles exhibit better rheological characteristics as compared to electrolytic iron (EI) particles. The use of MR fluids produces stable and natural limb movement in orthoses, lower limb prostheses, and exoskeletons. The MR fluids also prove to be very significant in polishing applications. There are various issues with preparation methods and difficulties in the storage of MR fluids. The problems encountered in the synthesis of MR fluids include sedimentation, agglomeration, in-use thickening, corrosion, erosion, etc. The impact of particle proportion, particle shapes, and size has been influential in evaluating MR characteristics. The viscosity and shear stress of MR fluid have been mitigated at higher values of temperature and even CI particles get oxidized at higher temperatures. The CI particles as compared to EI particles are the majority favourable particles used for dispersing state within the MR fluids due to their higher value of saturation magnetization, more availability, and lesser cost. The small-sized particles led to lower wettability, whereas larger-sized particles accounted for an increased sedimentation rate. The currently available MR fluids cost is still on the higher side and the preparation of economical MR fluid is still a big challenge for the researchers. The MR fluids storage is also a big concern. The future scope of MR fluid may be in heavy industries such as nuclear, shipbuilding, oil and gas, space and aviation, etc. to achieve the desired damping response.

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.

Study of the Attenuation Force Generated by a Magnetorheological Fluid in Industrial Robot Grippers Shock Absorbers

The attenuation force generated by the use of magnetorheological fluid (FMR) during the expansion and compression of the shock absorber in robot grippers has been studied. The shock absorber has a stroke of 25 mm and a volume of 4 071.50 mm3 in which the FMR made up of ferric micro-particles and nanoparticles is housed; this fluid modifies its rheological properties when exposed to a magnetic field of variable intensity generated by an electromagnet. The intensity of the magnetic field is gradually varied in order to obtain an attenuated and controlled dynamic force in the dissipation of energy. The research includes an analysis of magnetic field generation with the purpose that the particles of the fluid are aligned according to the polarity of the flow lines, thus forming a fibrillary structure chained in a few milliseconds. This magnetic field modifies the viscosity of the fluid, taking it from a low viscosity to a higher density state without altering its chemical composition and shape. The results are reflected in the direct correlation and in the obtaining of data where the saturation of the fluid is given to a maximum intensity of magnetic flux (B) of 0.01 Tesla; and a damping force of 6, 12 Newtons. This concludes that the theoretical and experimental analysis of attenuation in FMR based buffers serve to mitigate impact excitations, in order to provide a buffered velocity of motion.

Development and Testing of MR Damper

Conventionally systems are designed to resist the causes of vibrations through a combination of strength, deformability, and energy absorption. Use of Magnetorheological fluids in vibration absorbing dampers is one of the methods available for smart damping now days. The essential characteristic of MR fluids is their ability to reversibly change from free-flowing, linear viscous liquids to semi-solids having controllable yield strength in milliseconds when exposed to a magnetic field. Theoretical analysis was carried out for MR Damper, resulting equations are solved in MATLAB. Analytical model and experimental analysis results are compared.

A review of challenges and solutions in the preparation and use of magnetorheological fluids

This review of MRF (magnetorheological fluids or MR fluids) brings out the challenges in methods of preparation, difficulties encountered in storage and use, and possible solutions to overcome the challenges.Magnetorheological fluid in the rheological fluid domain has found use due to its ability to change its shear strength based on the applied magnetic field. Magnetorheological fluids are composed of magnetizable micron-sized iron particles and a non-magnetizable base or carrier fluid along with additives to counter sedimentation and agglomeration.Magnetorheological fluids can respond to external stimuli by undergoing changes in physical properties thus enabling several improved modifications in the existing technology enhancing their application versatility and utility. Thus, magnetorheological fluid, a rheological material whose viscosity undergoes apparent changes on application of magnetic field, is considered as a smart material. Such materials can be used for active and semi-active control of engineering systems.Many studies on the designs of systems incorporating MR fluids, mainly for vibration control and also for other applications including brakes, clutches, dynamometers, aircraft landing gears, and helicopter lag dampers, have emerged over last couple of decades. However, the preparation as well as the maintenance of magnetorheological fluids involves several challenges. Sedimentation is a major challenge, even when stored for moderate periods of time. A comprehensive review is made on the problems confronted in the preparation of magnetorheological fluids as well as sustenance of the properties, for use, over a long period of time. Other problems encountered include agglomeration and in-use thickening (IUT) as well as rusting and crusting. Of interest is the mitigation of these problems so as to prepare fluids with satisfactory properties, and such solutions are reviewed here. The control of magnetorheological fluids and the applications of interest are also reviewed.The review covers additives for overcoming challenges in the preparation and use of magnetorheological fluids that include incrustation, sedimentation, agglomeration, and also oxidation of the particles. The methodology to prepare the fluid along with the process for adding selected additives was reviewed. The results showed an improvement in the reduction of sedimentation and other problems decreasing comparatively. A set of additives for addressing the specific challenges has been summarized. Experiments were carried out to establish the sedimentation rates for compositions with varying fractions of additives.The review also analyzes briefly the gaps in studies on MR fluids and covers present developments and future application areas such as haptic devices.

Experimental Characterization of Surface Roughness Using Magnetorheological Abrasive Flow Finishing Process on AISI D3 Steel

The main objective of the present work is to develop a novel finishing process to polish the die steel materials with the use of magnetorheological fluid and also to investigate the effects of the input process parameters such as concentration of CIPs and abrasive particles (Al2O3), magnetizing current, speed of rotating tool, feed rate, working gap and hardness of workpiece on the response of surface roughness (Ra). In view of this, a novel MR fluid-based finishing setup is developed to characterize the process performance. Based on the method of full factorial design with two levels, 64 experiments are conducted on CNC vertical machining center with the customized setup. The results of the response are formulated by applying the ANOVA, and a mathematical model is established using linear regression to predict the response Ra. Capacity of the newly developed process is proven to achieve the surface finish on the hardness of 65 HRC D3 materials from 0.156 to 0.081 µm with the duration of polishing 10 min. The result of the experiments reveals that the major contributions of the parameters to improve the surface finish are working gap, magnetized current, and the hardness of the work piece, and followed by the rotating speed of tool, the ratio of CIP to abrasive, and feed rate of the work piece. The average percentage deviation between the predicted and observed surface roughness values is 3.56 within the band of 5% error. Scanning electron microscopy (SEM) is applied to characterize the integrity of the surface and testifies the efficacy of the developed MR fluid process to obtain a nano-level surface finish on the die steel material.

Two-Dimensional rGO-MoS2 Hybrid Additives for High-Performance Magnetorheological Fluid

Magnetorheological fluids (MRF) that undergo a change in their viscoelastic properties under the magnetic fields have been considered as one of most important smart functional materials for vibration dampers and shock absorbers in several engineering applications. However, the use of magnetorheological fluids in practical applications has been limited by poor sedimentation ratio and on-state yield stress. Herein, we report hybrid rGO-MoS2 additives for a high-performance magnetorheological fluid. Two different kinds of hybrid additives, which are called non-magnetic rGO-MoS2 and magnetic Fe-rGO-MoS2, were synthesized by using a hydrothermal method. The rGO-MoS2 added suspensions remained stable for the first 90 min whereas the CIP MRFs settled down quickly (65%) in the first 10 minutes. The Fe-rGO-MoS2 additives showed a 24% higher on-state shear stress as compared to CIP MRFs. On the other hand, an increase of 60% in the on-state yield stress for Fe-rGO-MoS2 MRF can be attributed to the gap-filling by the hybrid additives during columnar-structure formation. Among two-dimensional (2D) materials, Molybdenum Disulphide (MoS2) is a member of transition metal dichalcogenides (TMDCs), traditionally used as solid lubricant, while reduced graphene-oxide (rGO) is a well-known 2D material with supreme mechanical properties. We believe that this study will blaze the new way for developing a high-performance magnetorheological fluids based on various 2D material hybrids.

Investigation on Current Excitation of Magnetorheological-Fluid-Based Microbrake for Microturbine Generator

The microturbine generator performs highly efficiently and reliably in energy conversion. It has been widely used as a physical power source for microminiature flying objects. However, the rotational speed of the microturbine generator may exceed its rated speed when it moves at high speeds. A magnetorheological-fluid-based rotary brake is proposed to reduce the rotational speed of the microturbine generator. The microbrake demonstrates a favorable speed-reduction effect as a series of currents is applied to the coil. Moreover, the current excitation of the magnetorheological-fluid-based microbrake under the wind speed of is experimentally investigated. The decreasing rate of rotational speed ranges from 27.9 to 38.2%. A hybrid model for the magnetorheological-fluid-based microbrake was developed to explain the speed-reduction mechanism. The current-induced magnetic field distribution in the microbrake is calculated with a COMOSOL Multiphysics-based simulation method. The comparison between calculated curves and experimental results shows that the speed-reduction effect can be explained well by the developed model. The authors believe the proposed model is significant for designing the magnetorheological-fluid-based microbrake, expanding the scope of wind speed for the microturbine generator and promoting the use of magnetorheological fluid in aerospace and energy.

Magnetorheological Fluid Assisted Photochemical Machining

The advancement in the field of micro and nonconventional machining is provoking the manufacturers to improve the machining process and eventually optimize the process. The betterment of the process is thus being inevitable. Photochemical machining (PCM) is a technique where material removal takes place with control corrosion phenomenon. Chemical etching is performed over the chosen areas through the perforated photoresist layer, which results in machining of chosen areas. Surface roughness and undercut produced through the PCM process are still need to be improved as they hamper the quality of workpiece being machined. Magnetorheological (MR) fluid is one of the smart materials, encompasses microsized abrasive particles along with ferromagnetic particles utilized in polishing of the optical lenses to minimize the surface roughness. In this paper, the use of MR fluid to minimize undercut and surface roughness associated with the PCM process is discussed.

The Investigation of the Work-fluid Characteristics of Precision Hydraulic Active Vibration Control Module

Vibration control in the systems of precise positioning is an important problem that nanotechnology sector is facing. This problem challenges the engineers to develop advance positioning mechanisms such as hydraulic magnetorheological (MR) actuators or MR modules. These modules combine the characteristics of hydraulic systems and electromagnetic control because of the use of magnetorheological fluids instead of traditional hydraulic fluid. This allows to avoid using inertial valves that results in higher accuracy and dynamic characteristics as compared with conventional systems. The main element of a MR valve is a solenoid that creates a magnetic field to control viscosity and rheological behavior of the fluid due to structuring of the disperse phase of magnetic particles in magnetic field.The positioning error of the MR module depends, to great extent, on the minimum current which should be applied to the coil to start the motion. This work is aimed at the experimental study of the response of the MR module on the applied current. The response was measured as the pressure drop in the fluid at the exit of the MR module.It was found that the maximum magnetic field in the working gap of the module of 0.04 T corresponded to the pressure drop 0.12MPa. The results form the base for design of MR modules of automatic control systems operating under semi-active and active vibration control modes.

Boring Tool Chatter Suppression Using Magneto-Rheological Fluid Damper through Regression Models

Chatter is a problem of instability in the metal cutting process, especially in boring operation when the length of the hole to be bored is high. The phenomenon is characterized by violent vibrations, loud noise and poor quality of surface finish. Chatter causes a reduction of the life of the tool and affects the productivity by interfering with the normal functioning of the machining process. Many academic and industrial engineers reported the chatter suppression in turning operation; however, for boring operation, there is a lot of scope for studying the chatter suppression problem. This paper presents the use of magneto-rheological fluid for active chatter suppression through regression models. The vibration signals corresponding to different machining conditions were captured. The relevant features of the signals were extracted. The characterized magneto-rheological fluid was taken and regression models were built to suppress the tool chatter based on on-line vibration measurement. The models built in the study are linear regression model, support vector regression model and artificial neural network model. The regression model results are validated.

Design of shear gaps for high-speed and high-load MRF brakes and clutches

Magnetorheological fluids (MRF) are smart fluids with the particular characteristics of changing their apparent viscosity significantly under the influence of a magnetic field. This property allows the design of mechanical devices for torque transmission, such as brakes and clutches, with a continuously adjustable and smooth torque generation. Especially the use of MRF in devices for applications with the demand on high rotational speeds and high loads can offer advantages, because more dissipation energy and thermal load peaks can be compensated by the torque generating fluid volume. However, high rotational speeds can cause a centrifugation of the particles contained in the MRF especially in idle mode when no magnetic field is applied. This can yield on the one hand to labile and unpredictable behavior of the torque response and on the other hand to a higher wear of the MRF or in the worst case to a destruction of the MRF with respect to a long-term view. For ensuring reliable braking or coupling conditions, in this contribution the development of a Taylor-Couette flow with axisymmetric toroidal vortices in axial shear gaps of MRF brakes and clutches is considered. The developing flow profiles in these shear gaps are modeled and analyzed in detail and finally design rules for axial shear gaps are introduced. Measurements at high rotational speeds up to 6000min−1 with a test actuator based on this design prove the positive influence of the vortex flow on the homogeneity of the MRF suspension and on the consistency and predictability of the braking or coupling torque even under long-term conditions.

Theoretical and experimental analysis of MR valve

The properties of magnetorheological (MR) fluid can be rapidly varied by the application of a magnetic field. This behaviour allows the designer to construct a machine that's quality can be changed in action, according to the variation of the surround and to the expectations. The commercial use of MR fluid is already not limited in dampers and breaks. Thanks to the advantageous quality – that requires low voltage – is on the increase. Using the MR fluid in a valve, the pressure drop can be adjusted by the intensity of the magnetic field, without moving parts. In this work a MR valve has been designed, that can supply a hydrostatic bearing lubricated with magnetic fluid. Its behaviour has been simulated with three models. The analytical model based on the Bingham law of the magnetic fluid flow, the Buckingham model (Bingham modified) and the dimensional model suggested by Lord Corporation, the manufacturer of used MR fluid, MRF 122 2EG. The results of the simulations are compared with the experimental data.

Magnetorheological finishing process for hard materials using sintered iron-CNT compound abrasives

The use of magnetorheological fluids for finishing is one of the most promising smart processes for the fabrication of ultra-fine surfaces, particularly three-dimensional millimeter or micrometer structures. This process is not readily applicable to hard-surface materials, like an Al 2O 3–TiC hard disk slider, if a conventional rotating tool is used. This is due to the rotational speed and the resulting actual impressed abrasion energy limits, and the consequent low efficiency of the material removal rate. In this study, the main mechanism responsible for the decrease of the material removal rate on hard materials for a wheel-type magnetorheological finishing process is examined, both theoretically and experimentally, and a solution to this problem is devised via two approaches. The first uses a rectilinear alternating motion to improve processing conditions, and the second focuses on the use of more effective abrasives, namely magnetizable abrasives made of iron powders sintered with carbon nanotubes, which are new abrasives that have not yet been introduced in the field of surface finishing. Furthermore, it is shown that these abrasives increase the lifetime of consumables (magnetorheological fluid and abrasives) and the material removal rate.

A new leather

The use of magnetorheological fluids for finishing is one of the most promising smart processes for the fabrication of ultra-fine surfaces, particularly three-dimensional millimeter or micrometer structures. This process is not readily applicable to hard-surface materials, like an Al2O3–TiC hard disk slider, if a conventional rotating tool is used. This is due to the rotational speed and the resulting actual impressed abrasion energy limits, and the consequent low efficiency of the material removal rate. In this study, the main mechanism responsible for the decrease of the material removal rate on hard materials for a wheel-type magnetorheological finishing process is examined, both theoretically and experimentally, and a solution to this problem is devised via two approaches. The first uses a rectilinear alternating motion to improve processing conditions, and the second focuses on the use of more effective abrasives, namely magnetizable abrasives made of iron powders sintered with carbon nanotubes, which are new abrasives that have not yet been introduced in the field of surface finishing. Furthermore, it is shown that these abrasives increase the lifetime of consumables (magnetorheological fluid and abrasives) and the material removal rate.

Width of hard-surface roads

The use of magnetorheological fluids for finishing is one of the most promising smart processes for the fabrication of ultra-fine surfaces, particularly three-dimensional millimeter or micrometer structures. This process is not readily applicable to hard-surface materials, like an Al2O3–TiC hard disk slider, if a conventional rotating tool is used. This is due to the rotational speed and the resulting actual impressed abrasion energy limits, and the consequent low efficiency of the material removal rate. In this study, the main mechanism responsible for the decrease of the material removal rate on hard materials for a wheel-type magnetorheological finishing process is examined, both theoretically and experimentally, and a solution to this problem is devised via two approaches. The first uses a rectilinear alternating motion to improve processing conditions, and the second focuses on the use of more effective abrasives, namely magnetizable abrasives made of iron powders sintered with carbon nanotubes, which are new abrasives that have not yet been introduced in the field of surface finishing. Furthermore, it is shown that these abrasives increase the lifetime of consumables (magnetorheological fluid and abrasives) and the material removal rate.