Showing papers on "Magnetorheological fluid published in 2015"
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TL;DR: In this article, a comprehensive review on different methods of preparation and stabilization of magnetorheological fluids is presented, and rheological models and application of MR fluids are discussed briefly in this study.
340 citations
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TL;DR: In this article, the magnetorheological fluids are classified as smart materials with controllable rheological properties, and the fast growing application of magnetors in recent years has increased the...
Abstract: The magnetorheological fluids are classified as smart materials with controllable rheological properties. The fast growing application of magnetorheological fluids in recent years has increased the...
129 citations
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01 Oct 2015-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this paper, a smooth mirror-like surface is achieved with improved finishing rate by controlling two motions (axial and rotational) simultaneously on stainless steel workpiece similar to knee joint implant.
Abstract: Freeform complex surfaces have become an inevitable part of many devices to perform specific functions. Some of these components require nanolevel surface roughness value to meet the desired requirements in their applications. Finishing of freeform surfaces to nanometer surface roughness value is always difficult for any process. Rotational-magnetorheological abrasive flow finishing (R-MRAFF) process has been applied so far for finishing internal surfaces of relatively simple geometry. In this work, an attempt has been made to improve external topography of freeform surfaces using this process. Large hydrodynamic pressure coupled with magnetic fluid is the principal idea behind these experiments. A smooth mirror like finished surface is achieved with improved finishing rate (nanometer/min) by controlling two motions (axial and rotational) simultaneously on stainless steel workpiece similar to knee joint implant. Magnetorheological polishing fluid with different mesh sizes of abrasive particles and at different extrusion pressures is used to reduce final surface roughness value, to increase uniformity of surface finish on the freeform surface and to enhance finishing rate. Surface roughness ranging from 35 to 78 nm is achieved at various locations as compared to larger variation in Ra value obtained in the earlier research work.
90 citations
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TL;DR: In this article, various electrolytic and carbonyl iron powder based MR fluids have been synthesized by mixing grease as a stabilizer, oleic acid as an antifriction additive and gaur gum powder as a surface coating to reduce agglomeration of the MR fluid.
88 citations
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TL;DR: In this paper, the authors proposed a novel compact shock absorber with both damping and stiffness variable characteristics, which is developed based on MR fluid through an innovative design and a prototype is tested by MTS to characterize the variable damping properties.
Abstract: A shock absorber is an important device for vehicle suspension. The semi-active suspension requires the damping or stiffness of the shock absorber to be controllable. This paper proposed a novel compact shock absorber with both damping and stiffness variable characteristics. The shock absorber is developed based on MR fluid through an innovative design. A prototype is tested by MTS to characterize the variable damping and stiffness properties. A mathematical model that incorporated the Bingham model is established and an optimization method is adopted to identify the parameters. The coherence of experiments and the proposed model verified the control ability of dual damping and stiffness of the shock absorber.
83 citations
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TL;DR: In this article, two control approaches for magnetorheological dampers on cables based on collocated control without state estimation are formulated, which generate amplitude and frequency independent cable damping: cycle energy control and controlled viscous damping.
Abstract: SUMMARY
Two control approaches for magnetorheological (MR) dampers on cables based on collocated control without state estimation are formulated, which generate amplitude and frequency independent cable damping: cycle energy control and controlled viscous damping (CVD). The force tracking is solved by the inverted Bingham model whose parameters are fitted as function of current and frequency. Cycle energy control and CVD are experimentally validated by hybrid simulations and free decay tests on stay cables of the Sutong Bridge, China, and the Eiland Bridge, the Netherlands. The implementation of CVD on the Russky Bridge, Russia, includes two novelties: the force tracking also takes the actual MR damper temperature into account to ensure precise force tracking for MR damper temperatures −40 to +60 °C and the decentralised real-time control units with pulse width current modulation are installed next to each MR damper to avoid long direct current (DC) power lines with associated losses and thereby minimise power consumption. Copyright © 2014 John Wiley & Sons, Ltd.
80 citations
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TL;DR: According to the results, for preparing a stable and efficient magnetorheological (MR) fluid, additives should be utilized and 3 wt% of stearic acid was added to the MR fluid which led to an enhancement of the fluid stability over 92% at 25 °C.
Abstract: In this study, the stability and rheological properties of a suspension of carbonyl iron microparticles (CIMs) in silicone oil were investigated within a temperature range of 10 to 85 °C. The effect of adding two hydrophobic (stearic and palmitic) acids on the stability and magnetorheological effect of a suspension of CIMs in silicone oil was studied. According to the results, for preparing a stable and efficient magnetorheological (MR) fluid, additives should be utilized. Therefore, 3 wt% of stearic acid was added to the MR fluid which led to an enhancement of the fluid stability over 92% at 25 °C. By investigating shear stress variation due to the changes in the shear rate for acid-based MR fluids, the maximum yield stress was obtained by fitting the Bingham plastic rheological model at high shear rates. Based on the existing correlations of yield stress and either temperature or magnetic field strength, a new model was fitted to the experimental data to monitor the simultaneous effect of magnetic field strength and temperature on the maximum yield stress. The results demonstrated that as the magnetic field intensified or the temperature decreased, the maximum yield stress increased dramatically. In addition, when the MR fluid reached its magnetic saturation, the viscosity of fluid depended only on the shear rate.
79 citations
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TL;DR: In this article, a new magnetorheological elastomer isolator in shear-compression mixed mode was designed, and two different dimensions of two different types of elastomers were utilized in the isolator.
Abstract: A new magnetorheological elastomer isolator in shear–compression mixed mode is designed in this article. Two pieces of magnetorheological elastomer fabricated with different dimensions are utilized in the isolator. One magnetorheological elastomer operates on shear mode, and the other operates on compression mode. Next, a finite element method magnetic package is used to analyze the designed magnetic circuit system, and a test system is established to obtain the frequency response of magnetorheological elastomer isolator with mixed mode. It is found that the natural frequency of magnetorheological elastomer isolator changes greatly with variable current applied, and the amplitude of vibration is attenuated widely. Compared with the natural frequency of 0 A, the increment of natural frequency is up to 103% with applied current reaches to 1.5 A. Finally, the dynamic model of isolator system is established, and the stiffness and damping coefficients of magnetorheological elastomer isolator are identified by ...
78 citations
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TL;DR: In this paper, the authors proposed a semi-active control of the vibrations of a cantilever sandwich beam filled with an elastomer, which can be directly applied to engineering vibrating structural elements, for example helicopter rotors, aircraft wings, pads under machines, and vehicles.
76 citations
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TL;DR: In this article, the authors investigated the use of magnetorheological dampers to semi-actively control wind induced vibrations of a 1/20 scaled wind tower model in order to reduce the structural demand imposed to the steel tower.
75 citations
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TL;DR: In this article, the sedimentation stability of a carbonyl iron (CI)-based magnetorheological (MR) fluid was improved by wrapping CI particles with a polystyrene (PS) foam layer.
Abstract: The sedimentation stability of a carbonyl iron (CI)-based magnetorheological (MR) fluid was improved by wrapping CI particles with a polystyrene (PS) foam layer. The PS layer on the CI particles was synthesized via conventional dispersion polymerization and was subsequently foamed using a supercritical carbon dioxide fluid to produce core–shell structured particles. The density of particles decreased after the PS-layer wrapping and subsequent PS-layer foaming. The surface morphology was observed by scanning electron microscope (SEM) and the specific surface areas were determined by Brunauer–Emmett–Teller (BET) adsorption measurements. Both modifications (PS-layer wrapping and foaming) increased the surface roughness of the particles, yet preserved particle’s spherical shape. The effect of the volume expansion after modification on the magnetorheological properties was investigated by using a vibrating sample magnetometer (VSM) and a rotational rheometer. All suspensions tested presented similar MR behavio...
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TL;DR: In this paper, it was shown that if microscopic and macroscopic forces are linearly related, then Bingham and Mason number are inversely related, or, alternatively, the product of the Bingham number and the Mason number is a constant.
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01 Oct 2015-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this article, the effect of BEMRF on surface roughness values in terms of arithmetical mean roughness (Ra) was studied by applying ANOVA, and the maximum contribution was made by the working gap on the surface finish.
Abstract: Ball end Magnetorheological Finishing (BEMRF) is a novel finishing process employed in the finishing of 2D and 3D surfaces. The magnetorheological effect imparted by the magnetic particles introduced through water or other carrier medium governs the finishing action of BEMRF. Abrasive and carrier medium play a vital role in the surface quality of the silicon material exposed to BEMRF process. In the present study, deionized water was used as a carrier medium while cerium oxide acted as an abrasive to finish the silicon wafer. An experimental study through statistical design of experiments were employed to predict the effect of process parameters such as core rotational speed, working gap, and magnetizing current on a percentage reduction in surface roughness of silicon wafer in BEMRF process. Individual effect on surface roughness values in terms of arithmetical mean roughness (Ra) was studied by applying ANOVA. The maximum contribution is made by the working gap on the surface finish was found to be the most critical aspect. Coming next was the magnetizing current while the last contribution was provided by the core rotational speed.
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TL;DR: In this paper, the authors proposed a meandering pattern formed by multiple annular and radial gaps in order to extend the flow path length of magnetorheological fluid, which is important to increase the density of effective area.
Abstract: A novel concept of a compact magnetorheological valve is proposed based on the advance characteristics of magnetorheological fluid. The structural design consists of a meandering pattern formed by multiple annular and radial gaps in order to extend the flow path length of magnetorheological fluid. Extending the flow path of magnetorheological fluid is important in order to increase the density of effective area, so that the rheological properties of magnetorheological fluid can be widely regulated in a small size magnetorheological valve. The main objective of this article is to show that the pressure drop as one of the key performance indicators in a magnetorheological valve can be significantly increased using multiple annular and radial gaps configuration. In order to demonstrate the magnetorheological valve performance, simulation work using magnetic simulation software called finite element method-based software for magnetic simulation is conducted and combined with the pressure drop calculation using the derived magnetorheological valve model. Simulation results show that the magnetorheological valve with multiple annular and radial gaps is able to improve the achievable pressure drop. The discussion on the effect of gap size variations on the achievable pressure drop and the operational range of magnetorheological valve is also presented.
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TL;DR: This review paper classifies the MR valve based on the coil configuration and geometrical arrangement of the valve, and focuses on four different mathematical models for MR valve: Bingham plastic, Herschel–Bulkley, bi-viscous and Herschel-Bulkly with pre-yield viscosity (HBPV) models for calculating yield stress and pressure drop in the MR valves.
Abstract: Following recent rapid development of researches in utilizing Magnetorheological (MR) fluid, a smart material that can be magnetically controlled to change its apparent viscosity instantaneously, a lot of applications have been established to exploit the benefits and advantages of using the MR fluid. One of the most important applications for MR fluid in devices is the MR valve, where it uses the popular flow or valve mode among the available working modes for MR fluid. As such, MR valve is widely applied in a lot of hydraulic actuation and vibration reduction devices, among them are dampers, actuators and shock absorbers. This paper presents a review on MR valve, discusses on several design configurations and the mathematical modeling for the MR valve. Therefore, this review paper classifies the MR valve based on the coil configuration and geometrical arrangement of the valve, and focusing on four different mathematical models for MR valve: Bingham plastic, Herschel–Bulkley, bi-viscous and Herschel–Bulkley with pre-yield viscosity (HBPV) models for calculating yield stress and pressure drop in the MR valve. Design challenges and opportunities for application of MR fluid and MR valve are also highlighted in this review. Hopefully, this review paper can provide basic knowledge on design and modeling of MR valve, complementing other reviews on MR fluid, its applications and technologies.
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TL;DR: In this paper, a magnetorheological fluid (MRF)-based damper was proposed to combine the attributes of variable stiffness and damping through the compact assembly of two MRF damping units and a spring.
Abstract: This paper reports a novel magnetorheological fluid (MRF)-based damper, which synergizes the attributes of variable stiffness and damping through the compact assembly of two MRF damping units and a spring. The magnetic field densities of the two damping units were analyzed. After the prototype of the new MRF damper, a hydraulically actuated MTS machine was used to test the damper's performance, including stiffness variability and damping variability, amplitude-dependent responses and frequency-dependent responses. A new mathematical model was developed to describe the variable stiffness and damping MRF damper. The successful development, experimental testing and modeling of this innovative variable stiffness and damping MRF damper make the true design and implementation of the concept of variable stiffness and damping feasible.
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TL;DR: In this paper, a force tracking control scheme for magnetorheological (MR) dampers is presented. But the authors focus on the nonlinearity of the MR damper force and use a control-oriented mapping approach to compensate for it.
Abstract: SUMMARY
This paper describes a novel force tracking control scheme for magnetorheological (MR) dampers. The feed forward, which is derived by a control-oriented mapping approach to reduce modelling effort of the inverse MR damper behaviour, compensates for the main steady-state nonlinearity of the MR damper force and thereby linearizes the plant. The resulting force tracking error due to model imperfections and parameter uncertainties is reduced by parallel proportional and integral feedback gains that are formulated based on the absolute values of actual MR damper force and desired control force due to the semi-active constraint of the MR damper force. The feedback is enriched by an anti-reset windup to account for MR damper current constraints and the concept of current reversal to accelerate demagnetization. The experimental validations of the force tracking control scheme on a rotational and a long-stroke MR damper demonstrate its robustness and efficacy. Copyright © 2015 John Wiley & Sons, Ltd.
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TL;DR: In this paper, the isotropic magnetorheological elastomer samples are fabricated with and without addition of carbon blacks into the silicon rubber matrix and carbonyl iron particles in the absence of magnetic field.
Abstract: In this study, the isotropic magnetorheological elastomer samples are fabricated with and without addition of carbon blacks into the silicon rubber matrix and carbonyl iron particles in the absence of magnetic field. Microscopic and morphological analyses, thermo-gravimetric analysis, MH measurements, thermomechanical analysis, dynamic mechanical analysis, tensile test and magnetorheological test of magnetorheological elastomers are performed to characterize the fabricated magnetorheological elastomers. The experimental results demonstrate that the addition of carbon black improves the mechanical properties of the magnetorheological elastomer. The fabricated magnetorheological elastomers can be used in applications such as adaptive tuned vibration absorbers and vibration reduction in sandwich structures.
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TL;DR: It is shown that for multidomain ferromagnetic particles embedded in an elastomer matrix, as for paramagnetic ones in the same environment, pair clusters may form or break by a hysteresis scenario, but the magnetization saturation brings in important features to this effect.
Abstract: Field-induced magnetostatic interaction in a pair of identical particles made of a magnetically soft ferromagnet is studied. It is shown that due to saturation of the ferromagnet magnetization, this case differs significantly from the (super)paramagnetic one. A numerical solution is given, discussed, and compared with that provided by a simpler model (nonlinear mutual dipoles). We show that for multidomain ferromagnetic particles embedded in an elastomer matrix, as for paramagnetic ones in the same environment, pair clusters may form or break by a hysteresis scenario. However, the magnetization saturation brings in important features to this effect. First, the bistability state and the hysteresis take place only in a limited region of the material parameters of the system. Second, along with the hysteresis jumps occurring under the sole influence of the field, the "latent" hysteresis is possible which realizes only if the action of the field is combined with some additional (nonmagnetic) external factor. The obtained conditions, when used to assess the possibility of clustering in real magnetorheological polymers, infer an important role of mesoscopic magnetomechanical hysteresis for the macroscopic properties of these composites.
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TL;DR: In this article, a novel type of magnetorheological (MR) damper configuration is proposed to achieve low slope damping force in the pre-yield (low-piston-velocity) region and high magnitude of damping forces in the post-yielding (highpiston velocity) region.
Abstract: This work proposes a novel type of magnetorheological (MR) damper configuration from which an excellent ride comfort can be achieved without using a sophisticated controller scheme. The proposed novel MR damper is featured by piston bypass holes to achieve low slope of the damping force in the pre-yield (low-piston-velocity) region and high magnitude of the damping force in the post-yield (high-piston-velocity) region. A mathematical model for the damping force of the proposed MR damper is formulated followed by the investigation on damping characteristics with respect to several geometrical design parameters such as the number of piston bypass hole, the diameter of the hole, the gap size of the orifice, the orifice length, the diameter of the bobbin, and the height of the coil. After selecting the main design parameters from the simulation results, numerical simulations for the damping force characteristics are conducted with eight design parameter sets to evaluate the significant effect on the damping force performance. The proposed MR dampers are then manufactured with the same design parameter sets and the damping force characteristics are experimentally obtained and compared with the analytical simulation results. It is identified from the parametric investigations that the size and the number of the piston bypass hole are very important on damping force characteristics of the proposed MR damper.
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TL;DR: Rod-like hard-magnetic nanoparticles of γ-Fe2O3 were used as an additive to a soft magnetic carbonyl iron (CI) microsphere-based magnetorheological (MR) suspension to improve the dispersion stability of the MR fluid and enhance its MR performance.
Abstract: Rod-like hard-magnetic nanoparticles of γ-Fe2O3 were used as an additive to a soft magnetic carbonyl iron (CI) microsphere-based magnetorheological (MR) suspension to improve the dispersion stability of the MR fluid and enhance its MR performance. The morphology of the pure CI microspheres and CI/γ-Fe2O3 mixture particles were examined by scanning electron microscopy. The MR properties of pure CI and CI/γ-Fe2O3 mixtures were measured from steady and oscillatory tests under different magnetic field strengths. The results showed that the CI/γ-Fe2O3 MR fluid exhibited higher yield behaviors with an enhanced MR effect than that of the pure CI MR fluid due to the increased magnetic properties. Physically attached γ-Fe2O3 nanoparticles onto the surface of micron-sized CI particles improved not only MR performance but also dispersion stability of the MR particles.
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TL;DR: In this article, a comparison of different particle sizes on the shear stress of magnetorheological fluids has been presented using HORIBA Laser Scattering Particle Size Distribution Analyser.
Abstract: Magnetorheological fluids (MRF), known for their variable shear stress contain magnetisable micrometer-sized particles (few micrometer to 200 micrometers) in a nonmagnetic carrier liquid To avoid settling of particles, smaller sized (3-10 micrometers) particles are preferred, while larger sized particles can be used in MR brakes, MR clutches, etc as mechanical stirring action in those mechanisms does not allow particles to settle down Ideally larger sized particles provide higher shear stress compared to smaller sized particles However there is need to explore the effect of particle sizes on the shear stress In the current paper, a comparison of different particle sizes on MR effect has been presented Particle size distributions of iron particles were measured using HORIBA Laser Scattering Particle Size Distribution Analyser The particle size distribution, mean sizes and standard deviations have been presented The nature of particle shapes has been observed using scanning electron microscopy To explore the effect of particle sizes, nine MR fluids containing small, large and mixed sized carbonyl iron particles have been synthesized Three concentrations (9%, 18% and 36% by volume) for each size of particles have been used The shear stresses of those MRF samples have been measured using ANTON PAAR MCR-102 Rheometer With increase in volume fraction of iron particles, the MR fluids synthesized using “mixed sized particles” show better shear stress compared to the MR fluids containing “smaller sized spherical shaped particles” and “larger sized flaked shaped particles” at higher shear rate
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TL;DR: In this article, a micro magneto-rheological fluid device is designed by the method of outer magnetic coil to generate a mechanical loading less than 20 N. The results confirm that the method can obtain miniature device easily and control the magnetic field conveniently.
Abstract: The authors demonstrate that the micro magneto-rheological fluid device is designed by the method of outer magnetic coil to generate a mechanical loading less than 20 N. The results confirm that the method can obtain miniature device easily and control the magnetic field conveniently. The magnetic field, the channel gap, and the initial position of valve plug were optimized by finite element simulation and experimental test. Additionally, an impact force at the beginning can be eliminated by using a modeled synchronous linear current, which indicates that the micro-magnetorheological fluid damper has good soft-landing performance.
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TL;DR: The results suggest that optimization of rheological properties of ferrofluids is possible by carefully adding suitable silica nanoparticles, which may find practical applications such as dynamic seals, heat transfer, sensors, and opto-fluidic devices, etc.
Abstract: For many technological applications of ferrofluids, the magnetorheological properties require being precisely controlled. We study the effect of hydrophilic silica on the magnetorheology of an oil-based ferrofluid containing Fe3O4 nanoparticles of size ∼10 nm. We observe that the presence of silica nanoparticles lowers the yield stresses, viscoelastic moduli, and shear thinning behavior of the ferrofluid because of the weakening of dipolar interactions, which was evident from the observed lower yield stresses exponent (<2). The ferrofluid containing silica exhibits a dominant elastic behavior, a reduced hysteresis during the forward and reverse magnetic field sweeps, and a longer linear viscoelastic regime under nonlinear deformation. The Mason number plots at low shear rates and magnetic fields show deviations from the master curve in the presence of silica. The magnetic field induced microstructures, visualized using opto-magnetorheometer, showed columnar aggregate structures along the field directions,...
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TL;DR: This article proposes a nonparametric model, that is, an artificial neural network–based model with 3 input neurons, 18 hidden neurons, and 1 output neuron, to predict the magnetorheological elastomer isolator behavior, and uses the ant colony algorithm for model training to obtain the optimal weights.
Abstract: Laminated magnetorheological elastomer base isolator is regarded as one of the most promising candidates for realizing adaptive base isolation for civil structures. However, the intrinsic hysteretic and nonlinear behavior of magnetorheological elastomer base isolators imposes challenge for adopting the device to accomplish high-accuracy performance in structural control. Therefore, it is essential to develop an accurate model for symbolizing this unique characteristic before designing a feedback controller. So far, some classical parametric models, such as Bouc–Wen, Dahl, and LuGre, have been proposed to depict the hysteretic response of magnetorheological devices, that is, magnetorheological damper, which may also be used for describing the nonlinear behavior of magnetorheological elastomer base isolator. However, the parameter identification is difficult to implement due to the nonlinear differential equations existing in these models. Considering this problem, this article proposes a nonparametric mode...
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TL;DR: In this paper, four innovative multilayer magnetorheological elastomers (MRE) isolators with negative changing stiffness characteristics are prototyped for horizontal vibration reduction of a seat.
Abstract: Magnetorheological elastomers (MREs) are being used more and more for the development of isolators and absorbers to attenuate vibrations. In this study, four innovative multilayer MRE isolators with negative changing stiffness characteristics are prototyped for horizontal vibration reduction of a seat. For each MRE isolator, a magnetic system consisting of two permanent magnets and an electromagnetic coil was designed to realise negative changing stiffness. This performance of the MRE isolators was verified by the experimental results which indicate that the MRE isolators exhibit a controllable negative changing stiffness characteristic; and this was further verified by the measured natural frequency shift of the MRE isolators. An experimental platform was also developed to test the vibration suppression of the MRE isolators for a real truck seat suspension. The test results demonstrate that the ride comfort of the MRE isolator based seat suspension is significantly better than passive seat suspension.
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TL;DR: In this article, a ball end magnetorheological finishing (BEMRF) process was developed for finishing a flat as well as 3D workpiece surfaces, which is mainly finished by abrasives contained in MRP fluid.
Abstract: A ball end magnetorheological finishing (BEMRF) process was developed for finishing a flat as well as 3D workpiece surfaces. The BEMRF process has a wide scope in today's advanced manufacturing systems for finishing 3D complex surfaces. Magnetorheological (MR) polishing fluid is used as finishing medium in BEMRF process. The constituent of MR polishing (MRP) fluid includes ferromagnetic carbonyl iron powder, abrasives, and base fluid medium. The workpiece surface is mainly finished by abrasives contained in MRP fluid. Therefore, the different mesh size from 400 to 1200 and volume percent concentration from 5% to 25% of abrasives in MRP fluid were chosen as factors to study their effects on the developed process performance in terms of percent change in roughness values. Silicon carbide abrasives were chosen in the present experimental investigation. Experiments were performed on the ferromagnetic ground surfaces whose initial roughness values (Ra) were measured in the range of 0.428 to 0.767 µm. The exper...
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TL;DR: In this paper, the wave propagation in a tunable phononic crystal consisting of a porous hyperelastic magnetorheological elastomer (MRE) subjected to an external magnetic field was analyzed.
Abstract: This paper presents the wave propagation in a tunable phononic crystal consisting of a porous hyperelastic magnetorheological elastomer (MRE) subjected to an external magnetic field. Finite deformations and magnetic induction influence phononic characteristics of the periodic structure through altering the geometry and material properties of the unit cell. The governing equations for incremental time-harmonic plane wave motions superimposed on a static predeformed media are derived. Analytical and finite element (FE) methods are used to investigate dispersion relation and band structure of the phononic crystal for different levels of deformation and applied magnetic induction. It is demonstrated that large deformations and magnetic induction could transform the location and width of band-gaps.
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01 Apr 2015-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: A permanent magnetic yoke with a straight air gap was developed as the magnetic excitation unit, in order to improve the efficiency of magnetorheological (MR) polishing for ultra-smooth surface planarization.
Abstract: A permanent magnetic yoke with a straight air gap was developed as the magnetic excitation unit, in order to improve the efficiency of magnetorheological (MR) polishing for ultra-smooth surface planarization. Finite element modelling was used to simulate the magnetic performance of the newly developed yoke, which was found to agree well with the experimental measurement. With the developed MR polishing apparatus, the effects of trough speed, work and excitation gap width, particle concentration within the MR fluid and workpiece size on the material removal rate were systematically investigated. Final tests were performed on glass specimens to examine the polishing performance. The polishing area in the developed process was much larger than that of the conventional MR finishing process with a carrier wheel and ultra-smooth surface of 1 nm in R-a was achieved. (C) 2014 Elsevier Inc. All rights reserved.
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TL;DR: For efficient fast control of suspension systems with magnetorheological dampers controlled by semi-active algorithms, the time response of the magnetic damper is one of the most importan...
Abstract: For efficient fast control of suspension systems with magnetorheological dampers controlled by semi-active algorithms, the time response of the magnetorheological damper is one of the most importan...