scispace - formally typeset
Search or ask a question

Showing papers on "Magnetorheological fluid published in 2012"


Journal ArticleDOI
TL;DR: In this article, a combined experimental and theoretical study of the macroscopic response of a particular MRE consisting of a rubber matrix phase with spherical carbonyl iron particles is presented.
Abstract: Magnetorheological elastomers (MREs) are ferromagnetic particle impregnated rubbers whose mechanical properties are altered by the application of external magnetic fields. Due to their coupled magnetoelastic response, MREs are finding an increasing number of engineering applications. In this work, we present a combined experimental and theoretical study of the macroscopic response of a particular MRE consisting of a rubber matrix phase with spherical carbonyl iron particles. The MRE specimens used in this work are cured in the presence of strong magnetic fields leading to the formation of particle chain structures and thus to an overall transversely isotropic composite. The MRE samples are tested experimentally under uniaxial stresses as well as under simple shear in the absence or in the presence of magnetic fields and for different initial orientations of their particle chains with respect to the mechanical and magnetic loading direction. Using the theoretical framework for finitely strained MREs introduced by Kankanala and Triantafyllidis (2004) , we propose a transversely isotropic energy density function that is able to reproduce the experimentally measured magnetization, magnetostriction and simple shear curves under different prestresses, initial particle chain orientations and magnetic fields. Microscopic mechanisms are also proposed to explain (i) the counterintuitive effect of dilation under zero or compressive applied mechanical loads for the magnetostriction experiments and (ii) the importance of a finite strain constitutive formulation even at small magnetostrictive strains. The model gives an excellent agreement with experiments for relatively moderate magnetic fields but has also been satisfactorily extended to include magnetic fields near saturation.

339 citations


Journal ArticleDOI
TL;DR: The magnetorheological fluid dampers could offer an outstanding capability in semiactive vibration control due to excellent dynamical features such as fast response, environmentally robust characteristics, large force capacity, low power consumption, and simple interfaces between electronic input and mechanical output as mentioned in this paper.
Abstract: Magnetorheological fluid technology has gained significant development during the past decades. The application of magnetorheological fluids has grown rapidly in civil engineering, safety engineering, transportation, and life science with the development of magnetorheological fluid–based devices, especially magnetorheological fluid dampers. The magnetorheological fluid dampers could offer an outstanding capability in semiactive vibration control due to excellent dynamical features such as fast response, environmentally robust characteristics, large force capacity, low power consumption, and simple interfaces between electronic input and mechanical output. To address the fast growing demand on magnetorheological fluid damping technology in extensive engineering practices, the state-of-the-art development is presented in this article, which provides a comprehensive review on the structure design and its analysis of magnetorheological fluid dampers (or systems). This can be regarded as a useful complement to...

298 citations


Journal ArticleDOI
TL;DR: In this article, the actuation behavior of soft silicone-based magnetorheological elastomers in magnetic fields of variable strength was investigated, and it was shown that an inhomogeneous magnetic field gives rise to a reversible actu...
Abstract: The actuation behavior of soft silicone-based magnetorheological elastomers in magnetic fields of variable strength was investigated. An inhomogeneous magnetic field gives rise to a reversible actu...

161 citations


Journal ArticleDOI
TL;DR: In this article, a tunable stiffness and damping vibration isolator based on magnetorheological elastomers (MREs) was developed, and four MRE elements were used as the tunable springs, whose stiffness c...
Abstract: A tunable stiffness and damping vibration isolator based on magnetorheological elastomers (MREs) is developed. In this isolator, four MRE elements are used as the tunable springs, whose stiffness c...

158 citations


Journal ArticleDOI
TL;DR: In this article, the authors explore two control methodologies (in time and frequency domain) used to design semiactive controllers for suspension systems that make use of magnetorheological dampers.
Abstract: Suspension systems are one of the most critical components of transportation vehicles. They are designed to provide comfort to the passengers to protect the chassis and the freight. Suspension systems are normally provided with dampers that mitigate these harmful and uncomfortable vibrations. In this paper, we explore two control methodologies (in time and frequency domain) used to design semiactive controllers for suspension systems that make use of magnetorheological dampers. These dampers are known because of their nonlinear dynamics, which requires the use of nonlinear control methodologies for an appropriate performance. The first methodology is based on the backstepping technique, which is applied with adaptation terms and H∞ constraints. The other methodology to be studied is the quantitative feedback theory (QFT). Despite QFT is intended for linear systems, it can still be applied to nonlinear systems. This can be achieved by representing the nonlinear dynamics as a linear system with uncertainties that approximately represents the true behavior of the plant to be controlled. The semiactive controllers are simulated in MATLAB/Simulink for performance evaluation.

146 citations


Journal ArticleDOI
TL;DR: In this article, a self-sensing MR damper with power generation is proposed and investigated, which integrates energy harvesting, dynamic sensing and MR damping technologies into one device.
Abstract: Magnetorheological (MR) dampers are promising for semi-active vibration control of various dynamic systems. In the current MR damper systems, a separate power supply and dynamic sensor are required. To enable the MR damper to be self-powered and self-sensing in the future, in this paper we propose and investigate a self-sensing MR damper with power generation, which integrates energy harvesting, dynamic sensing and MR damping technologies into one device. This MR damper has self-contained power generation and velocity sensing capabilities, and is applicable to various dynamic systems. It combines the advantages of energy harvesting—reusing wasted energy, MR damping—controllable damping force, and sensing—providing dynamic information for controlling system dynamics. This multifunctional integration would bring great benefits such as energy saving, size and weight reduction, lower cost, high reliability, and less maintenance for the MR damper systems. In this paper, a prototype of the self-sensing MR damper with power generation was designed, fabricated, and tested. Theoretical analyses and experimental studies on power generation were performed. A velocity-sensing method was proposed and experimentally validated. The magnetic-field interference among three functions was prevented by a combined magnetic-field isolation method. Modeling, analysis, and experimental results on damping forces are also presented.

134 citations


Journal ArticleDOI
TL;DR: In this article, anisotropic magnetorheological elastomers (MREs) with four different mass percentages of iron powder were prepared in an external magnetic field and the inner structure of the samples was characterized by using computed tomography.
Abstract: Anisotropic magnetorheological elastomers (MREs) with four different mass percentages of iron powder were prepared in an external magnetic field. The inner structure of the samples was characterized by using computed tomography. It has been shown that this kind of non-destructive analysis of MRE samples can be efficiently used for a detailed structural investigation. It was found that even small changes in the mass content of the magnetic filler led to the formation of completely different morphologies, which were reproducible for all samples. There were the familiar column formations in patterns with a mass content of ~ 5% iron powder. Increasing the mass fraction to ~ 14% resulted in the formation of tubular structures. Samples with ~ 23 and ~ 33 wt% had a densely packed structure, where the particle formations broke up: meanders without particles penetrate the samples over the entire height like canyons.

123 citations


Journal ArticleDOI
TL;DR: In this paper, the elasticity of urethane magnetorheological elastomers (MREs) consisting of carbonyl-iron particles in a polyurethane matrix were studied.
Abstract: In this paper, urethane magnetorheological elastomers (MREs) consisting of carbonyl-iron particles in a polyurethane matrix were studied. The volume fraction of particles was equal to 11.5%. Three types of ferromagnetic particles were used, with average particle size ranging from 1 to 70 μm. The elastic (storage) modulus G ′ was measured as a function of angular frequency ω and strength of magnetic field. The measured G ′ values were approximated with empirical model. The highest magnetorheological effect has been found for samples with 6–9 μm carbonyl-iron powder. The highest increase in the yield stress is observed for samples with particles aligned at 30° to the magnetic field lines. It has been found that rheological properties strongly depend on the MRE microstructure, in particular on the size/shape of particles and their arrangement. By optimizing the particles size, shape and alignment, the stiffness of MREs has been increased under applied magnetic field.

116 citations


Journal ArticleDOI
TL;DR: In this paper, a design optimization method that has been carried out for the objectives of target damper force and maximum magnetic flux density of an MR damper has been presented, a new approach that is use of magnetic field and MR flow together and simultaneously has specified optimal design values.

113 citations


Journal ArticleDOI
TL;DR: In this article, the phase behavior of polymer solutions and composites is studied using X-ray micro-computed tomography (XμCT) for better understanding of the microstructure formation in magnetorheological elastomers.
Abstract: The phase behavior of polymer solutions and composites is a complex issue and is of both technological and fundamental interest. For a better understanding of the microstructure formation in magnetorheological (MR) elastomers, x-ray micro-computed tomography (XμCT) investigations were carried out. Magnetorheological elastomers with 5% mass content of iron powder were prepared under different magnetic field strengths between 1 and 220 kA m−1. Through quantitative analysis, valuable information was obtained regarding the number, size and frequency distribution of column structures in MR elastomers, as well as the magnetic field required to force structure formation.

111 citations


Journal ArticleDOI
TL;DR: In this paper, a semi-active tuned mass damper with magnetorheological damper (MR-STMD) is proposed to enhance the force of the passive spring stiffness.
Abstract: This paper describes the new concept of a semi-active tuned mass damper with magnetorheological damper (MR-STMD). The real-time controlled MR damper force emulates controlled damping and a superimposed controllable stiffness force to augment or diminish the force of the passive spring stiffness which enables us to control the MR-STMD natural frequency. Both the damping and natural frequency are tuned according to Den Hartog’s formulae to the actual dominant frequency of the main structure irrespective of whether it is a resonance or a forced frequency. The MR-STMD is experimentally validated on the Empa bridge with a 15.6 m main span for different added masses to shift its resonance frequency 12.2% andC10.4% away from its nominal value. The experimental results are compared to those obtained when the MR-STMD is operated as a passive TMD that is precisely tuned to the nominal bridge. The comparison shows that the MR-STMD outperforms the TMD both in the tuned and all de-tuned cases by up to 63%. Simulations of the MR-STMD concept point out that the proposed semi-active control algorithm is most suitable for MR-STMDs due to the small amount of clipped active forces. A sensitivity analysis demonstrates that the real MR-STMD could be even more powerful if the force tracking errors in the MR damper force due to the current driver and MR fluid dynamics and remanent magnetization effects could be further reduced. The MR-STMD under consideration represents the prototype of the 12 MR-STMDs that have been running on the Volgograd Bridge since late fall 2011. (Some figures may appear in colour only in the online journal)

Journal ArticleDOI
TL;DR: It is found that a volume fraction of nanoparticles not higher than 3% is enough to provide a long-lasting stabilization to MRFs containing above 30% iron microparticles, and this effect produces soft sediments by avoiding short-range attractions between the large iron particles.

Journal ArticleDOI
TL;DR: In this paper, a soft actuator using a magnetorheological elastomer is described and the magnetic circuit when a current is applied is described, and its operating principle is explained.
Abstract: This paper describes a novel soft actuator using a magnetorheological elastomer. First, the material characteristics in the magnetization process and major contributing factors to magnetization of the magnetic elastomer are shown. Second, an actuator using a magnetorheological elastomer combined with an embedded electromagnet is proposed. The magnetic circuit when a current is applied is described and its operating principle is explained. Finally, the static and dynamic motions and dynamic stress of the actuator are determined by an experimental prototype and measurement setup.

Journal ArticleDOI
TL;DR: In this paper, the elastic and deformational behavior of soft magnetic elastomers with hard magnetic fillers under the influence of a magnetic field is studied by different experimental techniques, and it is shown that due to high residual magnetization the materials demonstrate well pronounced nonelastic behavior already in the absence of any external magnetic field.

Journal ArticleDOI
TL;DR: In this article, a ball end shape of magnetorheological polishing fluid is generated at the tip surface of the rotating tool which is used as a finishing spot for 3D workpiece surfaces.
Abstract: A nanofinishing process using ball end magnetorheological (MR) finishing tool was developed for finishing 3D workpiece surfaces. In this process a ball end shape of MR polishing fluid is generated at the tip surface of the rotating tool which is used as a finishing spot. This paper is focused on surface finishing and performance evaluation of a typical three-dimensional ferromagnetic workpiece using a ball end magnetorheological finishing process. A typical 3D workpiece surfaces were made by milling process at different angles of projection such as flat, 30°, 45° and curve surfaces. The experiments were performed on these typical workpiece surfaces by ball end MR finishing setup to study the effect of number of finishing passes on final surface roughness. The experiments were also performed on a flat ground surface to study the process performance as compared with the milled workpiece surfaces. The finite element analysis has been done to study the distribution of magnetic flux density at tip surface of the tool with an inserted typical 3D workpiece surfaces. When these typical workpiece surfaces were finished by proposed MR finishing process, the surface roughness were reduced as low as 16.6 nm, 30.4 nm, 71 nm and 123.7 nm respectively on flat, 30°, 45° and curve surfaces for 60 passes of finishing. The roughness of flat ground surface was reduced as low as 19.7 nm for 120 min of finishing. The experimental results demonstrated that the newly developed ball end magnetorheological finishing process was effective in finishing typical 3D ferromagnetic workpiece surfaces.

Journal ArticleDOI
TL;DR: In this paper, two different theories are proposed to model the effect of abrasive particles concentration in the magnetorheological fluid based finishing process and a normal and tangential squeeze force model is also proposed based on the theory of rolling process.

Journal ArticleDOI
TL;DR: The evidence that the magnetic particles embedded in the gel were aligned in the direction of magnetic fields, accompanied by stretching of the gel network concludes that the giant magnetoelastic phenomenon originates from the chain structure consisting of magnetic particles similar to magnetic fluids.
Abstract: A new class of magnetoelastic gel that demonstrates drastic and reversible changes in storage modulus without using strong magnetic fields was obtained. The magnetic gel consists of carrageenan and carbonyl iron particles. The magnetic gel with a volume fraction of magnetic particles of 0.30 exhibited a reversible increase by a factor of 1400 of the storage modulus upon a magnetic field of 500 mT, which is the highest value in the past for magnetorheological soft materials. It is considered that the giant magnetoelastic behavior is caused by both high dispersibility and high mobility of magnetic particles in the carrageenan gel. The off-field storage modulus of the magnetic gel at volume fractions below 0.30 obeyed the Krieger–Dougherty equation, indicating random dispersion of magnetic particles. At 500 mT, the storage modulus was higher than 4.0 MPa, which is equal to that of magnetic fluids, indicating that the magnetic particles move and form a chain structure by magnetic fields. Morphological study r...

Journal ArticleDOI
TL;DR: In this article, a semi-active industrial shock absorber with magnetorheological fluid was used to stop a mass moving on an inclined plane, where the braking force was adjusted by an electronic control system according to the current position of the moving mass.

Journal ArticleDOI
TL;DR: In this article, a new generation of magnetorheological elastomers based on hard magnetic particles is investigated, and the authors fabricate and characterize the actuation properties of hard magnetic materials.
Abstract: This study investigates a new generation of magnetorheological elastomers based on hard magnetic particles. Unlike traditional magnetorheological elastomers that use iron particles, a dispersion of hard magnetic materials aligned in an electromagnetic field will produce a magnetorheological elastomer with magnetic poles. When a magnetic field is applied, perpendicularly to these poles, the filler particles generate torque and cause rotational motion of the magnetorheological elastomer blend. The primary goal of this study is to fabricate and characterize the actuation properties of magnetorheological elastomers filled with various hard magnetic particles. To this end, samples of magnetorheological elastomers consisting of hard magnetic materials were fabricated using four different particle types, and a test setup (electromagnet) was constructed. After mounting the magnetically anisotropic samples in a fixed-free configuration, uniform magnetic fields are applied to the samples (perpendicular to the poled...

Book ChapterDOI
12 Sep 2012
TL;DR: Magnetorheological elastomers (MREs) belong to the new group of the functional materials called "smart" as mentioned in this paper, and their intensive development started in the end of the XXth century.
Abstract: Magnetorheological elastomers (MREs) belong to the new group of the functional materials called “smart”. Although smart materials are known since long time, their intensive development started in the end of the XXth century. The term smart materials, intelligent materials or less frequently used adaptive materials or multifunctional materials, was introduced in the eighties of the twentieth century, when some materials, which were included in the group were already known. Till today there is no accepted universal definition of smart material, it is also not included in the encyclopedia devoted to these materials, published in 2002 [1, 2].

Journal ArticleDOI
02 Apr 2012-Langmuir
TL;DR: The experimental results demonstrate that upon magnetic field application these new ferro fluids develop yield stresses and magnetoviscous effects much greater than those of conventional ferrofluids, based on nanospheres of approximately 10 nm in diameter.
Abstract: This paper is devoted to the steady-state rheological properties of two new kinds of ferrofluids. One of these was constituted by CoNi nanospheres of 24 nm in diameter, whereas the other by CoNi nanofibers of 56 nm in length and 6.6 nm in width. These ferrofluids were subjected to shear rate ramps under the presence of magnetic fields of different intensity, and the corresponding shear stress values were measured. From the obtained rheograms (shear stress vs shear rate curves) the values of both the static and the dynamic yield stresses were obtained as a function of the magnetic field. The magnetoviscous effect was also obtained as a function of both the shear rate and the magnetic field. The experimental results demonstrate that upon magnetic field application these new ferrofluids develop yield stresses and magnetoviscous effects much greater than those of conventional ferrofluids, based on nanospheres of approximately 10 nm in diameter. Besides some expected differences, such as the stronger magnetorheological effect in the case of ferrofluids based on nanofibers, some intriguing differences are found between the rheological behaviors of nanofiber ferrofluids and nanosphere ferrofluid. First, upon field application the rheograms of nanofiber ferrofluids present N-shaped dependence of the shear stress on the shear rate. The decreasing part of the rheograms takes place at low shear rate. These regions of negative differential viscosity, and therefore, unstable flow is not observed in the case of nanosphere ferrofluids. The second intriguing difference concerns the curvature of the yield stress vs magnetic field curves. This curvature is negative in the case of nanosphere ferrofluid, giving rise to saturation of the yield stress at medium field, as expected. However, in the case of nanofiber ferrofluid this curvature is positive, which means a faster increase of the yield stress with the magnetic field the higher the magnitude of the latter. These interesting differences may be due to the existence of strong interparticle solid friction in the case of nanofiber ferrofluids. Finally, theoretical models for the static yield stress of the ferrofluids were developed. These models consider that upon field application the ferrofluid nanoparticles are condensed in drops of dense phase. These drops tend to be aligned along the field direction, opposing the flow of the ferrofluids and being responsible for the static quasielastic deformation and the yield-stress phenomena. By considering the existence of interparticle dry friction only in the case of nanofiber ferrofluids, the developed models predicted quite well not only the magnitude of the static yield stress but also the differences in curvature of the yield stress vs magnetic field curves.

Journal ArticleDOI
TL;DR: In this paper, the harmonic strain loadings were applied to the magnetorheological plastomer (MRP) to study their dynamic properties, and under different test conditions, nonlinearity which was induced by strain amplitude and driving frequency was generated.
Abstract: To fully understand the structure dependent mechanical property, the harmonic strain loadings were applied to the magnetorheological plastomer (MRP) to study their dynamic properties. Under different test conditions, nonlinearity which was induced by strain amplitude and driving frequency was generated. In order to investigate the mechanism of nonlinearity, a facile and effective strategy by analyzing the response stress and actuating strain within an oscillatory cycle was introduced. In addition, the microstructures of isotropic and anisotropic MRP were observed and the time dependence of dynamic properties for MRP (from isotropic to anisotropic) under an 800 mT magnetic field was also investigated, which were helpful to further understand the structure dependent dynamic properties depending on actuating strain amplitude.

Journal ArticleDOI
TL;DR: In this paper, the capacity of plane capacitors is measured as a function of the intensity H of the magnetic field, and the tension and deformations field and elasticity module of anisotropic magnetorheological elastomers are determined.

Journal ArticleDOI
TL;DR: In this paper, the magnetoelastic homogenization framework and the partial decoupling approximation were used to estimate material properties for a class of magnetically susceptible elastomers.

Journal ArticleDOI
TL;DR: In this article, an experimental study was conducted to predict the effect of process parameters (concentration of magnetic particles and abrasive particles, carrier wheel speed, and initial surface roughness) on surface finish and material removal rate in MRF of single crystal silicon blank.

Journal ArticleDOI
TL;DR: Magnetorheological elastomer was prepared using silicone rubber and soft magnetic carbonyl iron microspheres, and then examined as dielectric materials for manufacturing electric capacitors as discussed by the authors.
Abstract: Magnetorheological (MR) elastomer was prepared using silicone rubber and soft magnetic carbonyl iron microspheres, and then examined as dielectric materials for manufacturing electric capacitors. As a specific element, capacity of the capacitors located in a magnetic field was found to be sensitive to both the MR suspension proportion to the silicone rubber and the intensity of the applied magnetic field. Viscoelastic characteristics of the MR elastomer, represented by storage modulus and creep behavior, were also studied.

Journal ArticleDOI
Miao Yu1, Benxiang Ju1, Jie Fu1, Xueqin Liu1, Qi Yang2 
TL;DR: In this paper, the carbon content of CIP has a greater impact on the dynamic mechanical properties of MRE and the damping property is also significantly influenced by carbon content, which is expected to provide guidance for fabrication of high performance MRE.

Journal ArticleDOI
TL;DR: In this article, an optimal solution of a new type of motorcycle brake featuring different smart magnetorheological (MR) fluids was presented, and a hybrid concept of magnetic circuit (using both axial and radial magnetic flux) to generate braking force was analyzed based on the finite element method.
Abstract: This work presents an optimal solution of a new type of motorcycle brake featuring different smart magnetorheological (MR) fluids. In this study, typical types of commercial MR fluid are considered there for the design of a motorcycle MR brake; MRF-122-2ED (low yield stress), MRF-132-DG (medium yield stress) and MRF-140-CG (high yield stress). As a first step, a new configuration featuring a T-shaped drum MR brake is introduced and a hybrid concept of magnetic circuit (using both axial and radial magnetic flux) to generate braking force is analyzed based on the finite element method. An optimal design of the MR brake considering the required braking torque, the temperature due to friction of the MR fluid, the mass of the brake system and all significant geometric dimensions is then performed. For the optimization, the finite element analysis (FEA) is used to achieve principal geometric dimensions of the MR brake. In addition, the size, mass and power consumption of three different MR motorcycle brakes are quantitatively analyzed and compared.

Journal ArticleDOI
TL;DR: In this paper, the authors revisited the yielding behavior of conventional magnetorheological (MR) fluids for a wide range of magnetic fields and particle concentrations under a colloidal gel perspective, and found a two-step yielding behavior at intermediate magnetic fields (∼10kA/m) that can be explained as a transition from a strong-link to a weak-link regime upon increasing the particle concentration in the MR fluid.
Abstract: The yielding behavior of conventional magnetorheological (MR) fluids is revisited for a wide range of magnetic fields and particle concentrations under a colloidal gel perspective. A two-step yielding behavior is found at intermediate magnetic fields (∼10 kA/m) that can be explained as a transition from a strong-link to a weak-link (or transition) regime upon increasing the particle concentration in the MR fluid. This two-step yielding behavior is reminiscent of the classical concepts of static (frictional) and dynamic (Bingham) yield stress. By relating macroscopic elastic properties to a scaling fractal model, we could identify the prevalent gelation regime in MR fluids.

Journal ArticleDOI
TL;DR: In this paper, the creep and recovery behaviors of magnetorheological plastomer (MRP) were systematically investigated to further understand its deformation mechanism under constant stress, and the experimental results suggested that the time-dependent mechanical properties of MRP were highly dependent on the magnetic field and the magnetic-controllable mechanism was discussed.
Abstract: The creep and recovery behaviors of magnetorheological plastomer (MRP) were systematically investigated to further understand its deformation mechanism under constant stress. The experimental results suggested that the time-dependent mechanical properties of MRP were highly dependent on the magnetic field and the magnetic-controllable mechanism was discussed. The influences of iron particle distribution and temperature on the creep and recovery behaviors in the absence and presence of a magnetic field were investigated, respectively. A great discrepancy was presented in creep curves for the isotropic and anisotropic MRP under an external magnetic field, which must be induced by the different particle assemblies. In addition, the creep strain of MRP tended to decrease with increasing temperature under a 930 mT magnetic field and this phenomenon was opposite to the results obtained without a magnetic field. Finally, a hypothesis was proposed to explain the temperature effect on the creep behaviors of MRP.