Characteristics Of Magnetorheological Fluid Research Articles

RESEARCH INTO THE PROPERTIES OF MAGNETIC FLUIDSPRODUCED BY MILLING TECHNOLOGY

Magnetic fluids are substances with controllable rheological properties, containing nano- or micro- sizedparticles with magnetic properties suspended in a carrier fluid. The production of such fluids poses variouschallenges, but the critical issue is the fabrication of magnetically active particles of known size and requiredproperties. They are usually produced using the ‘bottom-up’ method, where larger structures are formedduring chemical synthesis and physical processes. This method is the most economical and practical in termsof efficiency, mainly when producing nanoparticles. The essence of the second method, ‘top-down,’ involvesthe fragmentation of the material, mainly through chemical-mechanical processes like milling. This methodtakes more time but does not involve the generation of environmentally harmful substances. It is characterizedby simplicity and provides greater control over the sizes of the produced particles. The paper presents theresults of research on the production of magnetic fluids based on carbonyl iron powder, which was fragmentedusing a planetary micro-mill. Powders differing in particle size and magnetic properties were considered.Oleic acid and oleoyl sarcosine were used as surfactants. Particle size and rheological properties of theobtained magnetic fluids were examined. The aim of the study was to determine the feasibility of producingmagnetic fluids on a laboratory scale with designed physicochemical parameters. The research outcome isdeveloping a procedure for obtaining a magnetic fluid that combines ferrofluid and magnetorheological fluidcharacteristics.

Modeling, heat dissipation design, and force tracking control for temperature-dependent hysteresis of magnetorheological damper

The temperature-dependence (T-dependence) characteristics of magnetorheological fluids (MRFs) cause the damping force of magnetorheological dampers (MRDs) to change with temperature. The rapid temperature rise can lead to performance degradation or even failure of MRFs, reduced damping force of MRDs, and decline in control performance. In this paper, numerical simulations and predictions of the temperature rise characteristics of the MRD are performed and heat sinks are designed and optimized. The experimental results verify the efficiency of the simulations and predictions, and the heat sinks can significantly reduce the rate of temperature increase and improve the ability of the damper to operate for long hours. In order to accurately compensate for T-dependence characteristics of the MRD, a T-dependence hysteresis model and a model-based feedforward force tracking control method with disturbance observation of the MRD are proposed and validated by experiments. The experimental results indicate that the proposed T-dependence model has better prediction accuracy than the general hysteresis model, and the feedforward control method achieves good force tracking performance even without expensive force sensors.

The Roles of Magnetorheological Fluid in Modern Precision Machining Field: A Review

Owing to some of its specific advantages, magnetorheological fluid (MRF) has drawn significant attention in a broad range of modern precision machining fields. With the diversification and increase in demand, many novel structural configurations and processing methods have been applied to mechanical machining equipment. Although different applications using MRF have been proposed in the existing literature, the classification, latest approaches, and further trend are not understood clearly for the machining field. Therefore, the current applications such as machining auxiliary equipment and surface polishing equipment that used MRF are summarized from 2016 to 2020, in this article. Especially, some detailed structures of equipment are investigated, and relative limitations are analyzed based on the characteristics of MRF. Finally, in view of the current equipment, advantages and defects are briefly reported; the developing trends of modern precision machining with MRF are discussed. Therefore, in the state-of-the-art review, the significant role of MRF in the machining field is emphasized, which paves the way to innovative development and market selection.

Influence of different fumed silica as thixotropic additive on carbonyl particles magnetorheological fluids for sedimentation effects

The present work reports the influence of different types of surface area, hydrophobic, and hydrophilic fumed silica mixed in silicone oil as a thixotropic additive on carbonyl particles based magnetorheological fluids (MRFs) were prepared. Scanning electron microscopy analysis confirms the fumed silica particles attached to the surfaces of CIPs. The vibrating sample magnetometer result shows the MRF4 and 5 have a better magnetic saturation value of 30.12 emu/gm and 40.12 emu/gm, respectively. The experimental rheological flow curve behaviours are investigated using the magnetorheometer. The Herschel–Bulkley rheological model is found to be in good agreement with the experimental curves and suggested shear thinning property is observed. The results showed that the hydrophilic silica with larger surface area type presented (i.e.MRF 4 and 5) better magnetorheological fluid characteristics in terms of shear stress, with a high value of dynamic yield stress, and have much-improved sedimentation ratio up to seven days.

Single-double chains micromechanical model and experimental verification of MR fluids with MWCNTs/GO composites coated ferromagnetic particles

Magnetorheological (MR) fluid is a typical intelligent material which is widely adopted in the mitigation of civil engineering structures, and it is normally composed of nano-sized or micro-sized iron particles, carrier fluids and additives. Because of the complexity of its composition, it is one of the research hotspot to propose a micromechanical model which can effectively describe the micromorphological transformation as well as characteristics of MR fluids. In this study, a single-double chains micromechanical model of MR fluids is proposed by taking into consideration of the influence of volume fraction and magnetic induction on the microstructure evolution of MR fluids based on the coupled field as well as magnetic dipole theory. Additionally, the shear yield stress test of the self-prepared MR fluids with multi-wall carbon nanotubes(MWCNTs) and graphene oxide (GO) composites coated ferromagnetic particles is carried out by MCR302 rotational rheometer and the results have been compared with the theoretical values of the single-double chains micromechanical model to verify the effectiveness and accuracy of the proposed model.

Characteristics of Magnetorheological Fluids under New Formulation

Abstract Magnetorheological fluid (MRF), an intelligent material with controllable properties, has been widely used because of its unique magnetorheological effect and excellent rheological properties. Therefore, studying the preparation and performance of the system is crucial. First, the related equipment and raw materials were prepared at four volume percentages of MRF specimens—20 %, 33.3 %, 45.9 %, and 58.9 %. Then, on the basis of the pull method principle, we built a stress-testing device for an MRF yield. Furthermore, the yield stress values of the four kinds of MRFs were tested by the yield stress test device. Finally, the effect of temperature on the yield stress of the MRF was investigated. The experimental results show that the yield stress of the MRF decreases with increase of the temperature.

Design of a novel 6-DOF haptic master mechanism using MR clutches and gravity compensator

This work presents design and dynamic analysis results of a novel 6-degrees-of-freedom (6-DOF) haptic master mechanism featured by magneto-rheological (MR) devices and gravity compensator. The design target of the haptic master mechanism is determined on the basis of the possible application to the robotic-assisted minimally invasive surgery (RMIS) system in which a certain magnitude of the force or moment is required to feel by the surgeon. The dynamic torque/force models associated with MR clutches and brakes are derived considering the geometry and Bingham characteristics of MR Fluid. In the mechanism geometry, the wrist part is designed with a symmetrical structure such that the center of gravity is at the center of the handle. This makes the dynamic model of the proposed mechanism to be decoupled between the wrist motion and the translation motion. In addition, a gravity compensator is designed to enhance tracking performances of the desired repulsive forces/torques. It is demonstrated that the proposed 6-DOF MR haptic master can sufficiently generate desired rotational and translational forces/torques required in RMIS system.

Influence of Initial Surface Roughness on Tribological Characteristics of Magnetorheological Fluid Based on Damper Design

Influence of Initial Surface Roughness on Tribological Characteristics of Magnetorheological Fluid Based on Damper Design

Friction characteristics of magneto-rheological fluid on DLC- and PTFE-coated surfaces

In this study, the friction characteristics of a magneto-rheological fluid are examined with different surface process technologies such as polytetrafluoroethylene coatings and diamond-like carbon coatings by using a reciprocating friction tester. The friction characteristics of the magneto-rheological fluid are also examined with diamond-like carbon coatings at various temperatures. The substrate material (plate) used for coating with diamond-like carbon and polytetrafluoroethylene is aluminum (Al6061), which is widely used in engineering applications. The descending sequence of the coefficients of friction is Al6061 > diamond-like carbon > polytetrafluoroethylene. The surfaces are observed by scanning electron microscopy before and after the experiment. In addition, the chemical compositions of the worn surfaces were analyzed using energy-dispersive X-ray spectroscopy. By comparing the results, the friction characteristics of the magneto-rheological fluid are analyzed based on the different coating methods.

Research on Principle and Torque Transmission Model of Magneto-rheological Fluid Dual-clutch

Magneto-rheological fluid dual-clutch transmission (MRDCT) uses Magneto-rheological fluid (MRF) to replace the traditional friction to transmit torque. By controlling the current in the coil of the dual clutch, the magnetic flux density is changed, and the separation and combination of the dual clutch is realized. Based on the characteristics of MRF and MFC, MRDC is proposed. The principle of MRDC is introduced. The torque transmission models of plate-style and cylindrical MRDC are established and the torque transmission formulas are driven.

Repulsive torque control of a robot-assisted surgery system using a magnetorheological haptic master

In this work, a repulsive torque control of a robot-assisted surgery system using a 4-degree-of-freedom haptic master which is operated using the properties of magnetorheological fluid is undertaken. The proposed haptic master can generate a repulsive torque along 4-degree-of-freedom motion and provide command signals to the slave robot. This is possible due to controllability of the torque by applying the magnetic field (or current) to magnetorheological fluid domain of the clutch system. For the realization of the master-slave robot-assisted minimally invasive surgery system, an encoder is integrated with the haptic master, and the motion command of the haptic master is realized by the surgical slave robot in the robot-assisted minimally invasive surgery architecture. The haptic master–slave system is then established by incorporating the slave robot with the master device, in which the repulsive torque and position commands are transferred to each other. In order to demonstrate superior performance of the proposed haptic master in terms of torque-tracking controllability between the master and surgical positions, a sliding mode controller is designed and experimentally implemented. It is validated via tracking experiment that superior torque-tracking control performance can be achieved by commanding dynamic motions of the haptic master featured by the inherent characteristics of magnetorheological fluid.

Testing of magnetorheological fluids for shock loadings

The problem of applying magnetorheological fluids in damping systems of shock loadings is considered. The physical prerequisites of controlling the characteristics of magnetorheological fluids with internal electromagnetic fields are examined. Processes occurring in magnetorheological fluids under shock loadings are studied. The criterion for selecting a magnetorheological fluid for such problems is the appearance of electromagnetic pulses on windings of solenoid designed to generate an internal controlling magnetic field. The amplitude and duration of these pulses is a function of shock loadings. It is necessary to take their influence into account when developing magnetorheological dampers for shock loadings.

A new measurement method of magnetic flux density using magnetorheological fluid characteristics and a variable resistor circuit

This work proposes a new approach with which to measure the magnetic flux density using the characteristics of magnetorheological fluid (MRF) that is integrated with a variable resistor. For convenience, it is called a magnetorheological fluid variable resistor (MRF-VR) system in this study. The mechanism of the MRF-VR is based on the interaction between ferromagnetic iron particles of the MRF due to an external magnetic field, which causes its electrical resistance to be field dependent. Using this salient principle, the proposed MRF-VR system is constructed with electrodes and MRF, and its performance is demonstrated by evaluating its electrical resistive characteristics such as dimensional influence, response time, hysteresis and frequency response. After evaluating the performance characteristics, a feedback control system with a proportional–integral–derivative (PID) controller is established, and resistance-trajectory control experiments are carried out. Based on this MRF-VR system, a magnetic field–sensing system is constructed using a Wheatstone bridge circuit, and a polynomial model for calculating the magnetic flux density is formulated from the measured voltage. Finally, the accuracy and effectiveness of the proposed sensing system associated with the empirical polynomial model is successfully verified by comparing the calculated values of magnetic flux density with those measured by a commercial tesla meter.

Development and Experimental Investigation of MRF Damper Behavior under Triangular Excitation of Damper Input Current

Magneto-rheological (MR) fluids are materials that respond to an applied magnetic field with a dramatic change in rheological behavior. An MR fluid will be in a free-flowing liquid state in the absence of magnetic field, but under a strong magnetic field its viscosity can be increased by more than two orders of magnitude in a very short time (milliseconds) and it exhibits solid-like characteristics. The strength of an MR fluid can be described by shear yield stress. Moreover, the change in viscosity is continuous and reversible, i.e. after removing the magnetic field the MR fluid can revert to a free-flowing liquid. Using these characteristics of MR fluids, MR fluid devices have the ability to provide simple, quiet, rapid-response interfaces between electronic controls and mechanical systems. Hence scholars and industrialists have shown extensive interest in MR fluids and their applications. The devices based on MR fluids, including dampers, clutches, polishing devices and hydraulic valves, etc., have a very promising potential future; some of them have been used commercially in engineering applications such as automobiles, polishing machines, exercise equipment, etc. The focus of this research is to develop a fundamental understanding of MR dampers for the purpose of designing and implementing these “smart” damping devices in automotives and structures for vibration mitigation. The damper is to be designed, developed and tested for different configurations i.e. changing the MR fluid, changing the material of the housing, changing the gap dimension, changing the coil wire diameter and increasing the number of steps of the coil. The study in this research is intended to provide insight into the behavior of MR fluid dampers and their potential applications to various vibration problems. This work is expected to accelerate the implementation of these dampers in the areas of vibration mitigation in mechanical and civil engineering applications.

Research on the Dynamometer Temperature Characteristics of Magneto-Rheological Fluid Dynamometer

The dynamometer measuring device through the magnetic rheological fluid self-designed, analyzes the basic characteristics of magneto rheological fluid, and then through the experimental study on the temperature characteristics of magneto rheological fluid. Dynamometer with magneto rheological fluid (MRF) was tested, in different conditions, when the system reached the steady state, temperature changes in the key points of the rotary. And through the analysis, the temperature distribution of the device was obtained, which provides the theoretical basis for the effect of temperature on transmission performance. Then, the obtained results, which can provided a good reference for the design of MRF gearing to optimum design and intelligent cooling system.

The Research of Capacitance Characteristics of MRF

With the development of theory that research on Magneto-Rheological Fluids (MRF), the MRF have been used in many fields in our life. The electrical characteristics of MRF can be widely used in automatic control, medical, automotive, aircraft manufacturing and many other areas .Firstly, this article have derived the formula of MRF between capacitance and Dielectric constant, made the Capacitors which can load the MRF. And then we measure the change of capacitance which is filled with the MRF when the time of magnetic field change, And we also measure the sensitivity of the dielectric constant of different concentrations of MRF as the magnetic field changes. And at last, we have made the curve of the capacitance - magnetic induction intensity the experimental results have been analyzed. We have the conclusion that when the magnetic field increases, the dielectric constant is also increases, resulting in increased capacitance of the conclusions of MRF. Introduction

An Experimental Investigation on Tribological Characteristics of Magnetorheological Fluids: Wear and Friction

An Experimental Investigation on Tribological Characteristics of Magnetorheological Fluids: Wear and Friction

Tension and Shearing Characteristics of Magneto Rheological Fluid under Magnetic Fields

The mechanical properties of a magneto rheological (MR) fluid in tension and shearing have been studied in the magnetic field which is generated by a coil carrying different magnitudes of DC electrical current. An experiment setup was designed and fabricated to perform this operation. The magnetic behavior of the equipment was analyzed using software of ANSYS/Multiphysics. The shear yield stress represents the effect of the interaction force along the shear direction (perpendicular to the direction of the magnetic field). The tensile yield stress of MR fluids represents the effect of the interaction force between the polarized particles along the direction of the applied magnetic field. The shearing tests showed that the shear yield stress is proportional to the external magnetic flux density with an exponent of 1.19. The tensile yield stress is about four times of shear yield stress.

Wear and Friction Characteristics of Magnetorheological Fluid under Magnetic Field Activation

In this article, wear and friction characteristics of a magnetorheological (MR) fluid were studied under different magnetic fields. Using a pin-on-disc tribometer, the wear loss and friction coefficient were obtained with and without a magnetic field. The friction and wear of three typical materials under magnetic field were investigated at various normal loads and rotating speeds. After the wear tests, the worn surfaces of specimens were observed using a scanning electron microscope (SEM) in order to investigate the wear mechanisms, and the contacting surfaces were analyzed by energy-dispersive X-ray spectroscopy (EDS) to investigate the variation of elemental composition on the worn surface. Test results showed that the MR fluid exhibits better tribological characteristics under a magnetic field compared to the case without a magnetic field. The general morphology of the MR particles and wear debris was observed to assist with the analysis of friction and wear. The SEM micrographs and EDS spectra of the worn surfaces showed that the predominant wear mechanism in the case of the steel and brass specimens was abrasive wear by asperities and MR particles on the worn surfaces, whereas a mixed wear mechanism that included adhesive wear and abrasive wear was observed in the case of the aluminum specimen.

Design and Performance Evaluation of Magnetorheological Fluids Under Single and Mixed Modes

Magnetorheological (MR) fluids are capable of providing continuously variable damping forces in response to a magnetic stimulus. Most MR devices have exploited the variable shear or flow characteristics of MR fluids. Greater potential application in vibration control/isolation may be sought if these fluids are utilized in the squeeze mode in which displacement levels are limited to few millimeters, but large force levels are available. In this article, the results of an experimental assessment of the comparative performance of MR fluids in dynamic squeeze, shear-flow, and mixed modes are presented. A mixed-mode MR cell comprising a cylinder which provides the reservoir for the fluid and a piston was designed and fabricated. The cylinder is subjected to an oscillatory sinusoidal motion while the piston is fixed. This motion simultaneously subjects the fluid sandwiched between the parallel circular-planes of the cell to compressive and tensile loadings, and the fluid contained in the cylindrical gap to a combined shear and flow loading. The magnetic field required to energize the fluid is provided by a pair of toroidally shaped coils, disposed symmetrically about the cylinder/piston centreline. This arrangement permits a separate excitation of the fluid contained in the circular or cylindrical gaps to simulate either a squeeze mode or a shear-flow mode, respectively, in addition to a simultaneous excitation of the fluid to simulate a mixed squeeze and shear-flow mode. The cell was tested under various loadings and magnetic field intensity conditions. Comparisons between the different modes of operation were carried out and the transmitted force level was seen to be greatly enhanced when the fluid was employed under the mixed mode. In addition, the implications of the results to vibration control, where MR fluids are utilized in short-stroke damping applications, are discussed.