Showing papers on "Magnetorheological fluid published in 2014"
TL;DR: In this paper, the authors present a state-of-the-art review on the recent progress of magnetorheological elastomer technology, with special emphasis on the research and development of MR elastomers and their applications.
Abstract: During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors’ knowledge and experience.
498 citations
TL;DR: It is found that the Payne effect significantly increases in the presence of an external magnetic field and varies with the cyclical loading which reaches saturation after several cycles.
Abstract: The dynamic modulus and the loss factor of magnetorheological elastomers (MREs) of various compositions and anisotropies are studied by dynamic torsion oscillations performed in the absence and in the presence of an external magnetic field. The emphasis is on the Payne effect, i.e. the dependence of the elastomer magnetorheological characteristics on the strain amplitude and their evolution with cyclically increasing and decreasing strain amplitudes. MREs are based on two silicone matrices differing in storage modulus (soft, G′ ∼ 103 Pa, and hard, G′ ∼ 104 Pa, matrices). For each matrix, the concentration of carbonyl iron particles with diameters of 3–5 μm was equal to 70 and 82 mass% (22 and 35 vol%, respectively) in the composite material. Samples for each filler content, isotropic and aligned-particles, are investigated. It is found that the Payne effect significantly increases in the presence of an external magnetic field and varies with the cyclical loading which reaches saturation after several cycles. The results are interpreted as the processes of formation–destruction–reformation of the internal filler structure under the simultaneously applied mechanical force and magnetic field. Impacts of matrix elasticity and magnetic interactions on the filler alignment are elucidated.
132 citations
TL;DR: In this paper, a new concept for MR damper with a combination of shear and squeeze working modes was presented, and the experimental tests were performed under quasi-static loading in three different conditions; shear mode, squeeze mode and combination of both modes.
106 citations
TL;DR: In this paper, the interaction between two particles made of an isotropic linearly polarizable magnetic material and embedded in an elastomer matrix is studied, and an interpolation formula for the resistance of the elastic matrix to the field-induced particle displacements is proposed.
Abstract: The interaction between two particles made of an isotropic linearly polarizable magnetic material and embedded in an elastomer matrix is studied. In this case, when an external field is imposed, the magnetic attraction of the particles, contrary to point dipoles, is almost wraparound. The exact solution of the magnetic problem in the linear polarization case, although existing, is not practical; to circumvent its use, an interpolation formula is proposed. One more interpolation expression is developed for the resistance of the elastic matrix to the field-induced particle displacements. Minimization of the total energy of the pair reveals its configurational bistability in a certain field range. One of the possible equilibrium states corresponds to the particles dwelling at a distance, the other—to their collapse in a tight dimer. This mesoscopic bistability causes magnetomechanical hysteresis which has important implications for the macroscopic behavior of magnetorheological elastomers.
89 citations
TL;DR: In this paper, a multi-functional polymer composite (MPC) with both excellent shear stiffening (ST) performance and magnetorheological (MR) effect is prepared by dispersing magnetic particles into shear-stiffening polymer matrix.
Abstract: A novel multi-functional polymer composite (MPC) with both excellent shear stiffening (ST) performance and magnetorheological (MR) effect is prepared by dispersing magnetic particles into shear stiffening polymer matrix. Besides having the magnetically dependent mechanical properties (MR effects), this multi-functional MPC automatically changes its rheological behavior in response to external shear stimuli. The mechanical properties of this smart composite can be alternatively achieved by varying the particle's types and contents. Upon applying a shear stress with excitation frequency from 1 Hz to 100 Hz, the storage modulus (G′) of the MPC increases from 102 to 106 Pa, demonstrating an excellent ST effect. Interestingly, the ST effects of the MPC are also tunable by varying the external magnetic field, and the area of G′ could be greatly increased and precisely controlled. Based on the experimental results, a possible mechanism is proposed and discussed. It is believed that the “cross bonds” and the particle chains induced by the magnetic field are due to the excellent multi-functional stimulus-response properties.
83 citations
TL;DR: In the presence of a magnetic field, the presented MAEs exhibit a strong magneto-induced change in storage modulus resulting in a colossal magnetorheological effect of >106 % which is ∼30 times higher than previously reported values as discussed by the authors.
Abstract: Highly compliant elastomers with a shear storage modulus as low as 25 Pa are prepared using commercially available silicone, plasticizer, and tactile mutator silicone additive. They are used as matrix material for magneto-active elastomers (MAEs) with carbonyl iron contents between 0 and 85 wt %. In the absence of an external magnetic field, the storage modulus of MAEs based on two selected mixtures ranges between ∼100 Pa and ∼2000 Pa. Addition of a mutator to the matrix mixture results in a long post-cure period depending on the curing temperature and the initial mixture. In the presence of a magnetic field, the presented MAEs exhibit a strong magneto-induced change in storage modulus resulting in a colossal magnetorheological effect of >106 % which is ∼30 times higher than previously reported values. The results are of interest in applications using such elastomers as cell substrates with magnetically tunable rigidity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39793.
80 citations
TL;DR: In this paper, the authors developed a compact squeeze MRE absorber and its subsequent performance in various magnetic fields characterized under various frequencies by a vibration testing system, which revealed that the natural frequency of the MRE absorbing working in squeeze mode can be tuned from 37 Hz to 67 Hz.
Abstract: In the past, adaptive tuned vibration absorbers (ATVAs) based on magnetorheological elastomers (MREs) have mainly been developed in a shear working mode. The enhancing effect of MREs in squeeze mode has already been investigated, but ATVAs in squeeze mode have rarely been studied. This paper reports the development of a compact squeeze MRE absorber and its subsequent performance in various magnetic fields characterized under various frequencies by a vibration testing system. The results revealed that the natural frequency of the MRE absorber working in squeeze mode can be tuned from 37 Hz to 67 Hz. Following this, a theoretical model based on magnetic dipole theory was developed to investigate the dynamic performance of the squeeze MRE absorber, and the vibration attenuation of the squeeze MRE absorber was then verified by mounting it on a beam with supports under both ends. The results revealed that the squeeze MRE absorber extended its vibration attenuation range from 37 Hz to 67 Hz while the passive absorber was only effective around 53 Hz.
80 citations
TL;DR: In this paper, a numerical and an experimental study of the dynamic behavior of sandwich plates consisting of two aluminum skins and a magnetorheological elastomer core of different loads of micron-size ferromagnetic particles elaborated under the action of a magnetic field is presented.
79 citations
TL;DR: The behavior of magnetic particles inside elastomeric matrices is a complex issue and can be influenced in many ways, e.g. by applying a magnetic field or external mechanical stimuli.
Abstract: The behavior of magnetic particles inside elastomeric matrices is a complex issue and can be influenced in many ways, e.g. by applying a magnetic field or external mechanical stimuli. It is of fundamental interest for theoretical descriptions and technological applications to study processes like structure formation of these particles in a magnetic field. For a better understanding of the microstructure and the motion of particles in magnetorheological elastomers (MRE), x-ray micro-computed tomography (Xμ-CT) investigations were carried out. A MRE with a quantity of 2 wt.% of iron powder and an isotropic allocation of the particles inside the matrix was prepared. By means of quantitative analysis with image processing software, information regarding the geometrical properties of the particles and their individual motion under the influence of a magnetic field was obtained. Therefore a set of three tomograms—a reference taken without magnetic field, a second tomogram in presence of an applied field and third one again taken at B = 0 mT—has been taken and compared. It is shown that the combination of Xμ-CT and digital image processing provides a tool for a quantitative analysis of single particle motion in a MRE forced by external stimuli.
79 citations
TL;DR: In this paper, the effect of particle shape (flakes) on the magnetorheological (MR) properties of an iron-based MR fluid, constituted of two different volume fractions of particles dispersed in a liquid carrier, is studied.
Abstract: In this work, the effect of particle shape (flakes) on the magnetorheological (MR) properties of an iron based MR fluid, constituted of two different volume fractions of particles dispersed in a liquid carrier, is studied. To compare the MR effect, spherical iron carbonyl particle based MR fluid is studied. In both MR fluids, linear viscoelastic behavior has been extensively investigated using small amplitude oscillatory analysis and magnetic sweep tests, in the presence and absence of a magnetic field (H). The amplitude sweep tests reveal that flake-based MR fluid shows a higher storage modulus compared to sphere-based MR fluid and saturates at a lower magnetic field strength. The variation of storage modulus with magnetic field strength shows an Hn dependence, where n varies from 2.2 to 2.4 for 20% volume fraction while it varies from 1.6 to 2 for a dilute sample. In the case of sphere-based MR fluid, at 20% volume fraction the variation of storage modulus is nearly linear with the magnetic field at low strain amplitude, and with increasing strain amplitude shows H2 dependence. At lower volume fraction in both cases, the loss modulus increases linearly with the magnetic field strength. The observed enhancement in the MR effect in the flake-based MR fluid is likely due to the stronger particle–particle interaction which results in higher friction between the particles. The sedimentation rate decreases by nearly 50% when flakes are used. The study reveals that one can use the irregular shaped particles for MR applications at low fields (~80 kA m−1).
73 citations
TL;DR: In this paper, a complete modeling in terms of torque density, efficiency, bandwidth, and controllability of magnetorheological (MR) brakes is presented. But the authors focus on a single disc and a single drum brake and highlight the interdependence of the measures of performance as a function of the dimensions.
Abstract: Design considerations for magnetorheological (MR) brakes are discussed for different geometries. A complete modeling in terms of torque density, efficiency, bandwidth, and controllability is presented. The model assigns a desired magnetic flux density over the fluid surface. The magnetic circuit dimensions and the necessary power can be calculated in consequence. The analysis focuses on a single disc and on a single drum brake and highlights the interdependence of the measures of performance as a function of the dimensions. The proposed models have been validated using finite-element analysis, the results demonstrate that both brakes are equivalent in terms of torque density but drum brakes are more reactive and require less power. The analysis has subsequently been extended to multiple-layered brakes with several fluid gaps in parallel. The performance are globally improved by increasing the number of gaps. Finally, the paper considers the influence of the MR fluid characteristics and housing material.
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27 Dec 2014
TL;DR: In this article, the magnetorheological shock absorbers can be used to solve the problem of where to get the ideas for a novel, which can be one of the right sources to develop a writing skill.
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TL;DR: In this paper, the authors present a general homogenization framework with application to magnetorheological elastomers under large deformation processes, where the macroscale and microscale magnetomechanical responses of the composite in the material and spatial description are presented and the conditions for a well-established homogenisation problem in Lagrangian description are identified.
Abstract: The aim of this work is to present a general homogenization framework with application to magnetorheological elastomers under large deformation processes. The macroscale and microscale magnetomechanical responses of the composite in the material and spatial description are presented and the conditions for a well-established homogenization problem in Lagrangian description are identified. The connection between the macroscopic magnetomechanical field variables and the volume averaging of the corresponding microscopic variables in the Eulerian description is examined for several types of boundary conditions. It is shown that the use of kinematic and magnetic field potentials instead of kinetic field and magnetic induction potentials provides a more appropriate homogenization process.
TL;DR: In this article, a low sedimentation magnetorheological fluid (MRF) was used to investigate the effect of plate-like iron particles on rheological properties such as yield stress and flow behavior.
Abstract: This study presents a new kind of low sedimentation magnetorheological fluid (MRF). Its salient properties are evaluated using a small-sized damper. The proposed MRF is characterized to investigate the effect of plate-like iron particles on rheological properties such as yield stress and flow behavior. Plate-like micron size iron particles play an important role in improving stability against rapid sedimentation as well as in enhancing the value of the yield stress. This study also considers a bidisperse MRF because this can produce a higher yield stress compared with a monodisperse suspension. Since the field-dependent yield stress is the key factor in mechanical applications, the physical properties of the MRF proposed in this work are evaluated and applied to the design of a small-sized damper which can be used for vibration control in washing machines. In order to verify the smaller effect on the damping force due to the particle sedimentation, the field-dependent damping forces are measured under two different operating conditions; one is just after filling the MRF and another after operating for 48 h. The proposed MRF is shown to be very effective in reducing adverse effects due to particle sedimentation.
TL;DR: In this article, the authors present results from experimental study to characterize fluid viscous dampers when subjected to half-cycle sine shock excitation, and a numerical study to evaluate the relative performance of structures with non-linear fluid drivable dampers subjected to short-duration shock (impulse) loading.
TL;DR: In this paper, the linear viscoelastic behavior of magnetorheological elastomers is analyzed according to their formulation and working conditions using a Physica MCR 501 rheometer from Anton Paar.
Abstract: The linear viscoelastic behaviour of magnetorheological elastomers is analysed in this work according to their formulation and working conditions. This study comprised both the synthesis of different magnetorheological elastomers and the strain and frequency sweep characterization under different magnetic fields and temperatures. The characterization was performed by a Physica MCR 501 rheometer from Anton Paar, equipped with a magnetorheologic cell 70/1T MRD. In the synthesis with a given elastomeric matrix, samples with different magnetic particle content are studied with two types of curing conditions: under the action of a magnetic field (anisotropic magnetorheological elastomers) and without a magnetic field (isotropic magnetorheological elastomers). The working conditions are excitation frequency, temperature and the applied external magnetic field. In this work, a new procedure to determine the linear viscoelastic behaviour is proposed; the loss factor is analysed in addition to analysing the storag...
TL;DR: In this paper, a meandering flow path is formed by combining multiple annular, radial and orifice flow channels to increase the effective area so that the MR fluid can be regulated within a small-sized valve.
Abstract: The huge developments in the field of magnetorheological (MR) fluid-based devices will have a great influence on the future of mechatronic applications due to the ease of interfacing between electronic controls and the mechanical components that they provide Among various MR fluid-based devices, an MR valve would be particularly significant for the development of other devices, if it could be successfully achieved One of the most challenging obstacles to MR valve development is the difficulty of achieving device miniaturization while, at the same time, improving the achievable performance This study demonstrates a novel design for an MR valve, using the meandering flow path approach in order to increase the effective area so that the MR fluid can be regulated within a small-sized valve The meandering flow path is formed by combining multiple annular, radial and orifice flow channels In order to analyze the valve performance, a mathematical model of the proposed MR valve is derived and combined with numerical simulation using the finite element method, with the intention of predicting the achievable pressure drop that can be generated by the valve The predicted MR valve performances are then experimentally evaluated using an oscillation-disturbed bypass hydraulic cylinder The simulation results show that the proposed MR valve design could yield substantial pressure drop improvement, which is confirmed by the experiment
TL;DR: It is shown that the orientation of resultant magnetic field and principal stress directions change with time owing to viscoelastic evolution.
Abstract: Iron-filled magnetorheological polymers, when cured in the presence of a magnetic field, result in having a transversely isotropic structure with iron particles forming chains along the direction of applied magnetic induction. In this work, we model the magneto-viscoelastic deformation (and magnetization) process of such polymers. Components of the deformation gradient and the applied magnetic induction in the direction of anisotropy are considered to be additional arguments of the energy density function. The existence of internal damping mechanisms is considered by performing a multiplicative decomposition of the deformation gradient and an additive decomposition of the magnetic induction into equilibrium and non-equilibrium parts. Energy density functions and evolution laws of the internal variables are proposed that agree with the laws of thermodynamics. In the end, we present solutions of some standard deformation cases to illustrate the theory. In particular, it is shown that the orientation of resultant magnetic field and principal stress directions change with time owing to viscoelastic evolution.
TL;DR: In this paper, the authors measured the normal and shear forces generated in the polishing zone during polishing of borosilicate glass and investigated the distribution of material removal rate.
TL;DR: In this article, the authors investigated the effect of a magnetic field on the variation of the natural frequencies and loss factors of a laminated composite magnetorheological (MR) fluid sandwich plate under various boundary conditions.
Abstract: This study investigates the dynamic properties of a laminated composite magnetorheological (MR) fluid sandwich plate. The governing differential equations of motion of a sandwich plate embedding a MR fluid layer as the core layer and laminated composite plates as the face layers are presented in a finite element formulation. The validity of the developed finite element formulation is demonstrated by comparing the results in terms of the natural frequencies derived from the present finite element formulation with those in the available literature. Various parametric studies are also performed to investigate the effect of a magnetic field on the variation of the natural frequencies and loss factors of the MR fluid composite sandwich plate under various boundary conditions. Furthermore, the effect of the thickness of the MR fluid layer and the ply orientation of the composite face layers on the variation of the natural frequencies and loss factors are studied. The free vibration mode shapes under various boundary conditions of a MR fluid laminated composite sandwich plate are also presented. The forced vibration response of a MR fluid composite plate is investigated to study the dynamic response of the sandwich plate under harmonic force excitations in various magnetic fields. The study suggests that the natural frequency increases with increasing magnetic field, irrespective of the boundary conditions. The reduction in peak deflection at each mode under a harmonic excitation force with variation of the applied magnetic field shows the effectiveness of the MR fluid layer in reducing the vibration amplitude of the composite sandwich plate.
TL;DR: In this paper, a kind of magnetoresistance material was prepared, named as magnetorheological gel (MRG), which was fabricated by dispersing carbonyl iron particles (CIP) into the polyurethane gel, and several experimental devices were prepared to investigate the magnetorsistance characteristics of MRG.
Abstract: A kind of magnetoresistance material was prepared, named as magnetorheological gel (MRG). The MRG samples were fabricated by dispersing carbonyl iron particles (CIP) into the polyurethane gel, and several experimental devices were prepared to investigate the magnetoresistance characteristics of MRG. The magnetoresistance characteristic was systematically tested and the influence of the magnetic field was analyzed. It is found that the resistance value of MRG with the CIP content of 70 wt % can be decreased from 7.56 to 2.44 MΩ with increasing of magnetic field from 0.1 T to 1 T. The experimental results have also proved that CIP content and the composition of matrix have a greater impact on the magnetoresistance characteristics. Because of the interaction between the magnetic force of CIP and motion resistance under a magnetic field, the obvious hysteresis phenomenon was observed and recorded. Lastly, it was observed that the magnetoresistance can be changed reversibly by controlling the magnetic field.
TL;DR: In this paper, a multi-objective optimization problem was formulated by considering the mechanical model of the recoil absorber employing a spring and a magnetorheological (MR) damper.
Abstract: Optimal control of a gun recoil absorber is investigated for minimizing recoil loads and maximizing rate of fire. A multi-objective optimization problem was formulated by considering the mechanical model of the recoil absorber employing a spring and a magnetorheological (MR) damper. The damper forces are predicted by evaluating pressure drops using a nonlinear Bingham-plastic model. The optimization methodology provides multiple optimal design configurations with a trade-off between recoil load minimization and increased rate of fire. The configurations with low or high recoil loads imply low or high rate of fire, respectively. The gun recoil absorber performance is also analyzed for perturbations in the firing forces. The adaptive control of the MR damper for varying gun firing forces provides a smooth operation by returning the recoil mass to its battery position (ready to reload and fire) without incurring an end-stop impact. Furthermore, constant load transmissions are observed with respect to the recoil stroke by implementing optimal control during the simulated firing events.
TL;DR: In this article, the effects of temperature on the material properties of magnetorheological (MR) fluid components are revealed, including the magnetization properties of the magnetic particle, as well as the shear viscosity and thermal expansion of the carrier fluid.
Abstract: Material properties of the components of magnetorheological (MR) fluids are critical to their control accuracy and service life. The aim of this study was to reveal the effects of temperature on the material properties of MR fluid components. In this paper, a detailed introduction to the components of MR fluids, including main performance indicators and commonly used materials, was presented at first. Then, theoretical analysis and experimental investigation were performed on the temperature-dependent material properties of MR fluid components. These material properties included the magnetization properties of the magnetic particle, as well as the shear viscosity and thermal expansion of the carrier fluid. Experimental results indicated that both the mass magnetization and coercivity of MR particles decreased as the temperature increased and the phenomenon was particularly obvious at high temperatures. Moreover, an increasing temperature could lead to a severe decrease of the shear viscosity and a relatively large thermal expansion of the carrier fluid. Research results from this study may serve to provide a theoretical and an experimental basis for the preparation of MR fluids with high thermal stability.
01 Feb 2014
TL;DR: In this paper, a magnetorheological fluid-based damper to attenuate vibration due to unbalanced laundry mass from a front-loaded washing machine is proposed and optimally designed with experimental validation.
Abstract: In this research, a magnetorheological fluid-based damper to attenuate vibration due to unbalanced laundry mass from a front-loaded washing machine is proposed and optimally designed with experimental validation. First, rigid vibration mode of the washing machine due to an unbalanced mass is analyzed, and an optimal positioning of the suppression system for the washing machine is figured out. In order to attenuate vibration from the washing machine, several configurations of magnetorheological damper are proposed considering available space and the required damping force of the system. Based on the Bingham rheological model of magnetorheological fluid, damping force of the proposed magnetorheological dampers is then derived. An optimal design problem for the proposed magnetorheological damper is constructed considering its zero-field friction force and the maximum damping force. The optimization objective is to minimize the zero-field friction force of the magnetorheological damper while the maximum value...
TL;DR: In this article, a multiphysics finite-element dynamic model for a small-scale magnetorheological (MR) damper is presented. But the model is not suitable for the case of tremor attenuation in patients suffering from pathological tremor.
Abstract: This paper introduces a multiphysics finite-element dynamic model for a small-scale magnetorheological (MR) damper. The model includes the analysis of the magnetic flux lines, field intensity, non-Newtonian fluid flow, and evaluation of the resistance force under prescribed motion and standard electrical test signals. A new regularized viscosity definition, which improves model solvability, is employed to describe the quasi-Bingham plastic behavior of the MR fluid. Extensive model validation was performed through comparison with the analytic model presented in the previous work and with the data from experimental testing. This model is intended to be used in the optimization of the MR dampers employed in the development of an upper limb orthosis, for tremor attenuation in patients suffering from pathological tremor.
TL;DR: In this article, an experimental investigation was carried out to study yield stress and viscosity of MR fluid based on the Bingham Plastic model by varying concentration of magnetorheological fluid constituents and magnetic flux density.
Abstract: The magnetorheological (MR) fluid-based finishing process is a well-known deterministic process for nanofinishing of soft, as well as brittle, materials. The quality of the finished surface mainly depends on the constituents of magnetorheological fluid and applied magnetic field. Rheological properties (yield stress and viscosity) of MR fluid significantly affect the quality of the final finished surface. An experimental investigation was carried out to study yield stress and viscosity of MR fluid based on the Bingham Plastic model by varying concentration of MR fluid constituents and magnetic flux density. The rheological properties are correlated with final surface roughness and material removal rate of single crystal silicon by MR fluid based finishing process. Viscosity and yield stress increased with an increase in percentage content of magnetic particles and magnetic flux density. Higher values of yield stress and viscosity increased the material removal rate and surface finish. Yield stress and vis...
TL;DR: In this article, an analytical model is proposed to simulate the theoretically expected behavior of electric resistance vs. the applied induction field gradient, so to predict the magneto-piezoresistive response and explain the obtained material tailoring.
Abstract: Composite material constituted by Fe micro-particles homogeneously dispersed in a silicone matrix, at a volume concentration slightly above the percolation threshold but separated by a thin silicone layer, was produced. The particle magnetic softness and their average size, have been properly improved with respect to previous investigations in order to maximize the piezo-resistive and the piezo-magnetic effects. The optimal combination of magneto-elasticity and piezo-resistivity enables to achieve a record value of magneto-piezo-resistivity sensitivity. An analytical model is proposed to simulate the theoretically expected behavior of electric resistance vs. the applied induction field gradient, so to predict the magneto-piezoresistive response and explain the obtained material tailoring. The experimental results have been in good agreement with the theoretically predicted behaviors, so validating the employed model and the interpretation of the phenomenon. A simple basic application in position sensing is also reported. The analytical model presented in this paper has demonstrated its potentiality to project further improvements, while the experimental results allow for different innovative applications.
TL;DR: In this article, the influence of nanosized particle concentration on rheological properties when mixed with a magnetorheological (MR) fluid was investigated, showing that the addition of nanoparticles to MR fluids increases the viscosity as well as the fluid stability under a magnetic field.
Abstract: We have investigated the influence of nanosized particle concentration on rheological properties when mixed with a magnetorheological (MR) fluid. We have also studied the structural, morphological and magnetic properties of ferrofluid-based MR fluids (F-MRFs). Field-induced rheological and viscoelastic properties of F-MRFs with varying shear rate and strain amplitude have been investigated. The Herschel–Bulkley model was found to fit well with the flow behaviour of F-MRFs. In the oscillatory strain sweep test, F-MRFs show linear viscoelasticity at low strain and the storage modulus (G′) is higher than the viscous modulus (G′′), which indicates the existence of strong links among the particles that form the microscopic structures. The storage modulus increases with increasing weight fraction of nanosized particles. Furthermore, the loss factor (ratio of G′′ and G′) was also investigated as a function of magnetic field strength. In addition, time-dependent relaxation behaviour of magnetically induced chain-like structures has also been described. The study reveals that the addition of nanoparticles to MR fluids increases the viscosity as well as the fluid stability under a magnetic field.
TL;DR: In this paper, the magnetorheological fluids (MRFs) based damper was evaluated in squeeze mode. The operation direction of this damper is parallel to the direction of the e...
Abstract: This research is focused on evaluation of the magnetorheological fluids (MRFs) based damper which works in squeeze mode. The operation direction of this damper is parallel to the direction of the e...
TL;DR: In this article, the magnetorheological properties of bimetallic alloy nanocomposites based on cross-linked polydimethylsiloxane elastomer and ferromagnetic FeCo3 nanoparticles were investigated.
Abstract: We investigate for the first time the magnetorheological (MR) properties of bimetallic alloy nanocomposites based on cross-linked polydimethylsiloxane elastomer and ferromagnetic FeCo3 nanoparticles. The nanoparticles (∼30 nm), with a saturation magnetization value of 166 emu/g, are synthesized by hydrazine reduction of Fe2+ and Co2+ metal ions. Isotropic and anisotropic nanocomposite films are prepared by a solution casting technique with 5, 10, and 20 wt % FeCo3 in the absence and presence of 0.2 T magnetic field, respectively. The structural, morphological, and magnetic properties of nanoparticles and their composites are characterized by X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, confocal and optical microscopy, and vibrating sample magnetometer analysis. Steady-state and dynamic mechanical properties of the nanocomposite under a magnetic field are evaluated by rotary shear, strain amplitude sweep, angular frequency sweep, and magnetic flux densit...