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R Tao - One of the best experts on this subject based on the ideXlab platform.
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Electrorheological Fluids under shear
International Journal of Modern Physics B, 2001Co-Authors: R Tao, J Zhang, Y Shiroyanagi, X Tang, Xianfeng ZhangAbstract:The behavior of an Electrorheological (ER) chain under a shear force is investigated theoretically and experimentally. Contrary to the conventional assumption that the ER chain under a shear force becomes slanted and breaks at the middle, we have found that there is symmetry breaking. When the shear strain is small, the chain becomes slanted with a space gap between the first and second particles (or between the last and next last particles). As the shear strain increases, the gap becomes wider and wider. When the shear strain exceeds a critical value, the chain breaks at the gap. The experiment also confirms that an ER chain under the shear breaks at either end, not at the middle. This symmetry breaking reflects the space's anisotropy, which is the result of the applied electric field.
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Electrorheological Fluids mechanisms properties technology and applications
1994Co-Authors: R Tao, G D RoyAbstract:Fundamental Characteristics of the Components of Various ER Active Systems (F E Filisko) The Polarization, Structuring and Rheology of ER Fluids (H Block et al.) Simulations of Solid Structure Formation in Electrorheological Fluids (R Tao et al.) Coarsening of a Quiescent Electrorheological Fluid (T Halsey) The Influence of Particle Size on the Dynamic Strength of Electrorheological Fluids (H Conrad et al.) First Experiments on Magneto-Electrorheological Fluids (V I Kordonsky et al.) Analysis of the Field Induced Structures in Electro and Magnetorheological Fluids (G Bossis et al.) Selection of Commercial Electro-Rheological Devices (D A Brooks) Magnetic-Induced Structure of Monodisperse Magneto-Emulsions (J Liu et al.) Electro-Rheological Catch / Clutch Simulations (A R Johnson et al.) Pressure Coupling in the Electric Response of Electro-Rheological Valves (M Whittle et al.). (Part contents).
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static shear stress of Electrorheological Fluids
Physical Review E, 1993Co-Authors: G L Gulley, R TaoAbstract:We have calculated the static shear stress of an induced Electrorheological solid for a single-chain structure, double-chain structure, triple-chain structure, and body-centered tetragonal (bct) lattice. When the shear strain is small, all of these four structures prefer slanted configurations which will come back to the original configurations if the load is removed. As the shear strain exceeds a yield point, the structures break into parts which cannot return to the original configurations in a short time. The bct lattice is found to have the strongest shear modulus. The triple-chain structure is weaker than the bct lattice, but much stronger than the single-chain structure and double-chain structure. The single-chain structure has the Peierls-Landau instability if the chain is very long. A double chain is stronger than a single chain if the chains are quite long and the situation is reversed if the chains are short.
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static shear stress of Electrorheological Fluids
Physical Review A, 1993Co-Authors: G L Gulley, R TaoAbstract:We have calculated the static shear stress of an induced Electrorheological solid for a single-chain structure, double-chain structure, triple-chain structure, and body-centered tetragonal (bct) lattice. When the shear strain is small, all of these four structures prefer slanted configurations which will come back to the original configurations if the load is removed. As the shear strain exceeds a yield point, the structures break into parts which cannot return to the original configurations in a short time. The bct lattice is found to have the strongest shear modulus. The triple-chain structure is weaker than the bct lattice, but much stronger than the single-chain structure and double-chain structure
Weijia Wen - One of the best experts on this subject based on the ideXlab platform.
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The research progress of Electrorheological Fluids
Chinese Science Bulletin, 2017Co-Authors: Mengying Zhang, Weijia WenAbstract:Electrorheological (ER) Fluids are such smart materials whose rheological properties (yield stress, viscosity, etc.) can be reversibly and continuously controlled using an external electric field. They are colloids composing of dielectric particles and insulating liquids. They switch from a liquid-like state to a solid-like state within a millisecond with the aid of an electric field, which is called the ER effect. ER Fluids can therefore be used as electrical and mechanical interfaces in various industries, including the fast acting valves, clutches, brakes, shock absorbers, accurate polishing, robotics and tactile displays. Since the ER effect was first described by Winslow in 1949, ER Fluids show a promising prospect in the application in various industries and a great deal of research interest in ER Fluids and ER devices has been stimulated. A large body of literature on ER Fluids, the mechanism of the ER effect, and the design of industrial applicable ER devices has been published. In the meantime, after the invention of ERF, a number of theories are put forward, such as Fibrillation Theory, “Water Bridge” Theory, Double layer Theory, Particle Polarization Theory and so on. Ma et al. calculated that the theoretical upper bound on conventional ER static yield stress is 10 kPa based on first-principles calculations. The highest yield strength of the dielectric Electrorheological fluid obtained by Lu et al. in the experiment is 5 kPa. However, Electrorheological Fluids are not industrialized practically because of the low yield strength. In recent years, Wen developed giant Electrorheological fluid that can reach a yield strength of 130 kPa, breaking the theoretical upper bound of traditional ER static yield stress. Later, Lu invented polar-molecule-dominated Electrorheological Fluids whose solid state can reach yield strength of 200 kPa. With the inventions of the giant Electrorheological fluid and polar-molecule-dominated Electrorheological Fluids with high yield stress under low electric field, there is a new opportunity for ER Fluids to apply to the industrial application because their yield strength of the new kind of ER Fluids is more than 40 kPa, the lowest practical limit. However, the problems about sedimentation and redispersibility of Electrorheological Fluids still restrict its wide application. With the research of surfactant and the development of the hollow multilayer porous nano particles, the stability of Electrorheological Fluids has greatly improved. This paper focuses on the study of the giant Electrorheological fluid and its application in smart microfluidics. Specifically, it gives a detailed introduction of micropumps and micro-valves and smart electroresponsive droplets in microfluidics based on giant Electrorheological Fluids. This paper also offers a review of the composition, macroscopic properties, microscopic mechanism and applications of Electrorheological Fluids, as well as a summary of its current research status and its future development. Research of the stability and service life of Electrorheological Fluids will definitely be the most popular topic in the future, thus accelerating the progress of industrialization with the settlement of the issues discussed above.
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Influence of carrier liquid on nanoparticle-based giant Electrorheological fluid:
Journal of Intelligent Material Systems and Structures, 2015Co-Authors: Ya Ying Hong, Weijia WenAbstract:The wetting characteristics of the giant Electrorheological particles and the suspending fluid were investigated. In contrast to the existing Electrorheological Fluids, giant Electrorheological par...
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Electrorheological Fluids structures and mechanisms
Soft Matter, 2008Co-Authors: Weijia Wen, Xianxiang Huang, Ping ShengAbstract:Electrorheology denotes the control of a colloid's flow properties through an electric field. We delineate the basic characteristics of Electrorheological (ER) Fluids, and show that the use of an effective dielectric constant concept can yield quantitative predictions. In particular, the ground state structure, the structural transition that occurs under crossed electric and magnetic fields, the high-field yield stress and its variation with particle size are all in good agreement with the experiments. The recently discovered giant Electrorheological effect, owing its origin to molecular dipoles, is described and contrasted with the conventional ER effect that arises from induced polarization effects.
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Polar molecule type Electrorheological Fluids
International Journal of Modern Physics B, 2007Co-Authors: Rong Shen, Xuezhao Wang, Gang Sun, Weijia Wen, Jixing LiuAbstract:The static and dynamic shear stress of newly developed Electrorheological (ER) Fluids can reach more than 100 kPa and over 60 kPa at 3 kV/mm, respectively. The high yield stress of those ER Fluids and its near linear dependence on the electric field are different from the conventional ER Fluids and can not be explained with traditional dielectric theory. Experiment demonstrates that the polar molecules adsorbed on the particles play crucial role in those ER Fluids, which can be named as polar molecule type Electrorheological (PM-ER) Fluids. To explain PM-ER effect a model is proposed based on the interaction of polar molecule-charge in between the particles, where the local electric field is much higher than the external one and can cause the polar molecules aligning. The main effective factors for achieving high-performance PM-ER Fluids are discussed.
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dielectric Electrorheological Fluids theory and experiment
Advances in Physics, 2003Co-Authors: Weijia Wen, Wing Yim Tam, Ping ShengAbstract:Electrorheological (ER) Fluids are a class of materials whose rheological properties are controllable by the application of an electric field. A dielectric Electrorheological (DER) fluid is the simplest type of ER fluid, in which the material components follow a linear electrostatic response. We review and discuss the progress of the studies on physics of this type of material. A first-principles theory of DER Fluids, along with relevant experimental verifications, are presented in some detail. In particular, the properties presented include static equilibrium structure, shear modulus, static yield stress and its variation with applied electric field frequency, and structure-induced dielectric nonlinearity.
Ping Sheng - One of the best experts on this subject based on the ideXlab platform.
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Electrorheological Fluids structures and mechanisms
Soft Matter, 2008Co-Authors: Weijia Wen, Xianxiang Huang, Ping ShengAbstract:Electrorheology denotes the control of a colloid's flow properties through an electric field. We delineate the basic characteristics of Electrorheological (ER) Fluids, and show that the use of an effective dielectric constant concept can yield quantitative predictions. In particular, the ground state structure, the structural transition that occurs under crossed electric and magnetic fields, the high-field yield stress and its variation with particle size are all in good agreement with the experiments. The recently discovered giant Electrorheological effect, owing its origin to molecular dipoles, is described and contrasted with the conventional ER effect that arises from induced polarization effects.
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dielectric Electrorheological Fluids theory and experiment
Advances in Physics, 2003Co-Authors: Weijia Wen, Wing Yim Tam, Ping ShengAbstract:Electrorheological (ER) Fluids are a class of materials whose rheological properties are controllable by the application of an electric field. A dielectric Electrorheological (DER) fluid is the simplest type of ER fluid, in which the material components follow a linear electrostatic response. We review and discuss the progress of the studies on physics of this type of material. A first-principles theory of DER Fluids, along with relevant experimental verifications, are presented in some detail. In particular, the properties presented include static equilibrium structure, shear modulus, static yield stress and its variation with applied electric field frequency, and structure-induced dielectric nonlinearity.
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Theory and Experiments on Electrorheological Fluids
International Journal of Modern Physics B, 1999Co-Authors: Ping Sheng, Yim Tam, Weijai Wen, M.m.t. LoyAbstract:By carrying out first principles calculations, particles fabrication and experiments, we demonstrate the enhancement of the Electrorheological effect through the use of microstructured composite particles, consisting of a spherical dielectric core coated with a thin layer of metal and an additional outer layer of insulating material with high dielectric constant. It is argued that through the choice of the core material and the outer layer material, the outer layer thickness, and the particle size, there can be a path of continuous improvement on the Electrorheological fluid properties that makes possible the eventual fulfillment of the diverse application requirements.
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Electrorheological Fluids using bidispersed particles
Journal of Materials Research, 1998Co-Authors: Weijia Wen, Yim Tam, Ping ShengAbstract:We report very large enhancement of static yield stress for Electrorheological Fluids by adding ferroelectric nanoparticles of lead zirconate titanate (PZT) or lead titanate (PbTiO3) to ER Fluids consisting of 50 μm glass spheres. It is found that the enhancement peaks at certain nanoparticle/microparticle ratios for fixed solid/liquid volume fractions. The results are explained by calculations using an effective medium approach, based on the physical picture that the nanoparticles modify the properties of the liquid and solid components.
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magnetic materials based Electrorheological Fluids
Applied Physics Letters, 1997Co-Authors: Weijia Wen, Ning Wang, Wing Yim Tam, Ping ShengAbstract:A type of Electrorheological (ER) system, denoted the magnetic materials-based Electrorheological Fluids, is introduced. The solid particles of this system are 40–50 μ-microspheres obtained by the sol–gel processing of a ferroelectric material containing a ferromagnetic component. Since the solid material is magnetic, the presence of a small magnetic field, such as that from a small permanent magnet, can suspend the microspheres in liquid. The incorporation of a small amount of magnetic materials thereby solves the long standing problem of particle sedimentation in ER Fluids. It is found that this type of ER fluid is very stable and exhibits a strong ER effect at low electric field.
Cholmin Sin - One of the best experts on this subject based on the ideXlab platform.
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Interior gradient estimate for steady flows of Electrorheological Fluids
Nonlinear Analysis: Real World Applications, 2020Co-Authors: Cholmin SinAbstract:Abstract In this paper, we consider the equations of stationary motion of Electrorheological Fluids in any dimension n ≥ 2 . We show that the first gradient of local solutions to the system has optimal L q -regularity with some q > 1 with respect to the one of the external force. This is achieved by comparison principle and a good λ -estimate.
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Global regularity of weak solutions for steady motions of Electrorheological Fluids in 3D smooth domain
Journal of Mathematical Analysis and Applications, 2018Co-Authors: Cholmin SinAbstract:Abstract In this paper, we first show higher integrability of the gradient of weak solutions for steady motions of Electrorheological Fluids under a further assumption on regularity of external force f in 3D smooth domain. Based on the higher integrability result, we then prove that any weak solution to the problem becomes global strong one under such an assumption on f. Moreover we improve the lower bound on p ( x ) for global regularity of solutions to the problem and their Stokes setting even if p ( x ) is a constant.
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the existence of weak solutions for steady flows of Electrorheological Fluids with nonhomogeneous dirichlet boundary condition
Nonlinear Analysis-theory Methods & Applications, 2017Co-Authors: Cholmin SinAbstract:Abstract In this paper, we show the existence of weak solutions for steady flows of Electrorheological Fluids with nonhomogeneous Dirichlet boundary condition under the condition p ( x ) > 2 n n + 2 , n = 2 , 3 . In particular, we improve a priori estimate for weak solutions to the problem with min p ( x ) 2 , which is an improvement even for constant p .
G L Gulley - One of the best experts on this subject based on the ideXlab platform.
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static shear stress of Electrorheological Fluids
Physical Review E, 1993Co-Authors: G L Gulley, R TaoAbstract:We have calculated the static shear stress of an induced Electrorheological solid for a single-chain structure, double-chain structure, triple-chain structure, and body-centered tetragonal (bct) lattice. When the shear strain is small, all of these four structures prefer slanted configurations which will come back to the original configurations if the load is removed. As the shear strain exceeds a yield point, the structures break into parts which cannot return to the original configurations in a short time. The bct lattice is found to have the strongest shear modulus. The triple-chain structure is weaker than the bct lattice, but much stronger than the single-chain structure and double-chain structure. The single-chain structure has the Peierls-Landau instability if the chain is very long. A double chain is stronger than a single chain if the chains are quite long and the situation is reversed if the chains are short.
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static shear stress of Electrorheological Fluids
Physical Review A, 1993Co-Authors: G L Gulley, R TaoAbstract:We have calculated the static shear stress of an induced Electrorheological solid for a single-chain structure, double-chain structure, triple-chain structure, and body-centered tetragonal (bct) lattice. When the shear strain is small, all of these four structures prefer slanted configurations which will come back to the original configurations if the load is removed. As the shear strain exceeds a yield point, the structures break into parts which cannot return to the original configurations in a short time. The bct lattice is found to have the strongest shear modulus. The triple-chain structure is weaker than the bct lattice, but much stronger than the single-chain structure and double-chain structure