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W.-j. Wen - One of the best experts on this subject based on the ideXlab platform.

  • The research progress of Electrorheological Fluids
    Chinese Science Bulletin, 2017
    Co-Authors: Mengying Zhang, W.-j. Wen
    Abstract:

    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.

  • DOI: 10.1007/128_2011_148 # Springer-Verlag Berlin Heidelberg 2011 Electrorheological Fluid and Its Applications
    2016
    Co-Authors: In Microfluidics, Xiuqing Gong, Limu Wang, W.-j. Wen
    Abstract:

    Abstract MicroFluidics is a low-cost technique for fast-diagnosis and microsynth-esis. Within a decade it might become the foundation of point-of-care and lab-on-a-chip applications. With microFluidic chips, high-throughput sample screening and information processing are made possible. The picoliter droplet runs in microFluidic chips are ideal miniaturized vessels for microdetection and microsynthesis. Mean-while, individual manipulation of microdroplets remains a challenge: the short-comings in automatic, reliable, and scalable methods for logic control prevent further integration of microFluidic applications. The giant Electrorheological Fluid (GERF), which is a kind of “smart ” colloid, has tunable viscosity under the influ-ence of external electric field. Therefore, GERF is introduced as the active con-trolling medium, with real-time response in on-chip Fluid control. This review article introduces the working principles and fabrication methods of different types of Electrorheological Fluid, and extensively describes the strategies of GERF-assiste

  • microdroplet based universal logic gates by Electrorheological Fluid
    Soft Matter, 2011
    Co-Authors: Mengying Zhang, Limu Wang, Xiuqing Gong, Xiang Wang, Jianhua Qin, W.-j. Wen
    Abstract:

    We demonstrate a uniquely designed microFluid logic gate with universal functionality, which is capable of conducting all 16 logic operations in one chip, with different input voltage combinations. A kind of smart colloid, giant Electrorheological (GER) Fluid, functions as the translation media among Fluidic, electronic and mechanic information, providing us with the capability of performing large integrations either on-chip or off-chip, while the on-chip hybrid circuit is formed by the interconnection of the electric components and Fluidic channels, where the individual microdroplets travelling in a channel represents a bit. The universal logic gate reveals the possibilities of achieving a large-scale microFluidic processor with more complexity for on-chip processing for biological, chemical as well as computational experiments.

  • Electrorheological Fluid and Its Applications in MicroFluidics
    Topics in current chemistry, 2011
    Co-Authors: Limu Wang, Xiuqing Gong, W.-j. Wen
    Abstract:

    MicroFluidics is a low-cost technique for fast-diagnosis and microsynthesis. Within a decade it might become the foundation of point-of-care and lab-on-a-chip applications. With microFluidic chips, high-throughput sample screening and information processing are made possible. The picoliter droplet runs in microFluidic chips are ideal miniaturized vessels for microdetection and microsynthesis. Meanwhile, individual manipulation of microdroplets remains a challenge: the shortcomings in automatic, reliable, and scalable methods for logic control prevent further integration of microFluidic applications. The giant Electrorheological Fluid (GERF), which is a kind of “smart” colloid, has tunable viscosity under the influence of external electric field. Therefore, GERF is introduced as the active controlling medium, with real-time response in on-chip Fluid control. This review article introduces the working principles and fabrication methods of different types of Electrorheological Fluid, and extensively describes the strategies of GERF-assisted microFluidic controlling schemes.

  • giant Electrorheological Fluid comprising nanoparticles carbon nanotube composite
    Journal of Applied Physics, 2010
    Co-Authors: Xiuqing Gong, W.-j. Wen, Shuyu Chen, Ping Sheng
    Abstract:

    We have fabricated suspensions exhibiting the giant Electrorheological (GER) effect comprising nanoparticles—multiwall carbon nanotubes (MCNTs) composite particles dispersed in silicone oil. This type of GER Fluids display dramatically enhanced antisedimentation characteristic without sacrificing the yield stress. The nanoparticles-nanotubes composites were fabricated by modifying the coprecipitation method with MCNTs and urea-coated barium titanyl-oxylate (BTRU) nanoparticles as the components. The composite solid particles are denoted MCNT-BTRU. In the best cases, stabilized suspensions with MCNT-BTRU particles dispersed in silicone oil have been maintained for several months without any appreciable sedimentation being observed. Both the sedimentary and rheological properties of the MCNT-BTRU suspension were systematically studied and compared with their BTRU counterparts. Yield stress as high as 194 kPa was obtained in the MCNT-BTRU suspensions. The MCNT-BTRU based GER Fluids, with their antisedimentat...

Jalil Rezaeepazhand - One of the best experts on this subject based on the ideXlab platform.

  • Aeroelastic stability of smart sandwich plates with Electrorheological Fluid core and orthotropic faces
    Journal of Intelligent Material Systems and Structures, 2012
    Co-Authors: Jafar Rahiminasab, Jalil Rezaeepazhand
    Abstract:

    The flutter of orthotropic sandwich plates with an Electrorheological Fluid layer subjected to supersonic airflow is discussed in this article. The sandwich plate consists of an Electrorheological Fluid layer, a base and a constraining orthotropic layer. The first piston theory is used to model the aerodynamic forces. Hamilton’s principle is employed to derive the finite element equations of motion. Taking the aerodynamic damping into account, an iterative complex eigenvalue solution is conducted to determine the flutter boundaries. The effects of electric field strength, Electrorheological layer thickness, Electrorheological Fluid type, constraining layer thickness, and fiber angle of orthotropic faces on the critical aerodynamic pressure are investigated. Both simply supported and clamped boundary conditions are considered. The results show that the Electrorheological core layer is capable of shifting the flutter instability of the system. It is also found that the Electrorheological Fluid type and the ...

  • Aeroelastic stability of smart sandwich plates with Electrorheological Fluid core and orthotropic faces
    Journal of Intelligent Material Systems and Structures, 2012
    Co-Authors: Jafar Rahiminasab, Jalil Rezaeepazhand
    Abstract:

    The flutter of orthotropic sandwich plates with an Electrorheological Fluid layer subjected to supersonic airflow is discussed in this article. The sandwich plate consists of an Electrorheological ...

Ping Sheng - One of the best experts on this subject based on the ideXlab platform.

  • giant Electrorheological Fluid comprising nanoparticles carbon nanotube composite
    Journal of Applied Physics, 2010
    Co-Authors: Xiuqing Gong, W.-j. Wen, Shuyu Chen, Ping Sheng
    Abstract:

    We have fabricated suspensions exhibiting the giant Electrorheological (GER) effect comprising nanoparticles—multiwall carbon nanotubes (MCNTs) composite particles dispersed in silicone oil. This type of GER Fluids display dramatically enhanced antisedimentation characteristic without sacrificing the yield stress. The nanoparticles-nanotubes composites were fabricated by modifying the coprecipitation method with MCNTs and urea-coated barium titanyl-oxylate (BTRU) nanoparticles as the components. The composite solid particles are denoted MCNT-BTRU. In the best cases, stabilized suspensions with MCNT-BTRU particles dispersed in silicone oil have been maintained for several months without any appreciable sedimentation being observed. Both the sedimentary and rheological properties of the MCNT-BTRU suspension were systematically studied and compared with their BTRU counterparts. Yield stress as high as 194 kPa was obtained in the MCNT-BTRU suspensions. The MCNT-BTRU based GER Fluids, with their antisedimentat...

  • Electrorheological Fluid dynamics
    Physical Review Letters, 2008
    Co-Authors: W.-j. Wen, Jianwei Zhang, Chun Liu, Ping Sheng, Xiuqing Gong
    Abstract:

    We use the Onsager principle to derive a two-phase continuum formulation for the hydrodynamics of the Electrorheological (ER) Fluid, consisting of dielectric microspheres dispersed in an insulating liquid. Predictions of the theory are in excellent agreement with the experiments. In particular, it is shown that whereas the usual configuration of applied electric field being perpendicular to the shearing direction can lead to shear thinning at high shear rates and thus the loss of ER effect, the interdigitated, alternating electrodes configuration can eliminate the shear-thinning effect.

  • Electrorheological Fluid Dynamics
    AIP Conference Proceedings, 2008
    Co-Authors: Jianwei Zhang, Chun Liu, Ping Sheng
    Abstract:

    We present the formulation of a two‐phase, electrical‐hydrodynamic model for the description of Electrorheological Fluid dynamics. By considering the energetics of (induced) dipole‐dipole interaction between the solid particles in terms of a field variable n(x), we employ the Onsager principle to derive the relevant coupled hydrodynamic equations, together with a continuity equation for n(x). Numerical solution of the relevant equations yields predictions that display very realistic behaviors as seen experimentally.

  • Electrorheological Fluid actuated microFluidic pump
    Applied Physics Letters, 2006
    Co-Authors: Liyu Liu, W.-j. Wen, Xize Niu, Xiaoqing Chen, Ping Sheng
    Abstract:

    The authors report the design and implementation of an Electrorheological (ER) Fluid-actuated microFluidic pump, with programmable digital control. Our microFluidic pump has a multilayered structure fabricated on polydimethylsiloxane by soft-lithographic technique. The ER microFluidic pump exhibits good performance at high pumping frequencies and uniform liquid flow characteristics. It can be easily integrated with other microFluidic components. The programmable control also gives the device flexibility in its operations.

  • Electrorheological Fluid actuated flexible platform
    Applied Physics Letters, 2006
    Co-Authors: Liyu Liu, W.-j. Wen, Xize Niu, Ping Sheng
    Abstract:

    The design, fabrication, and performance of an Electrorheological (ER) Fluid-actuated flexible platform integrated on a microFluidic chip are reported in this letter. The digitally regulated ER microvalves control the four diaphragms on which a platform is sustained. With electrical input signals, the platform can perform vibrations at tunable frequencies as well as generate complex leveling modes. The flexible platform can potentially act as a microdamper when its inputs are generated from a sensor, in combination with a feedback control system.

Tsunemoto Kuriyagawa - One of the best experts on this subject based on the ideXlab platform.

  • Fabrication of high-aspect ratio micro holes on hard brittle materials
    2016
    Co-Authors: Takumi Tateishi, Nobuhito Yoshihara, Jiwang Yan, Tsunemoto Kuriyagawa
    Abstract:

    -Study on Electrorheological Fluid-assisted micro ultrasonic machining

  • Control of the Behavior of Abrasive Grains by the Effect of Electrorheological Fluid Assistance - Study on Electrorheological Fluid-Assisted Micro Ultrasonic Machining -
    Advanced Materials Research, 2009
    Co-Authors: Takumi Tateishi, Nobuhito Yoshihara, Jiwang Yan, Keita Shimada, Tsunemoto Kuriyagawa
    Abstract:

    . Micro ultrasonic machining (micro-USM) is an effective machining method for hard brittle materials. In the micro-USM process, the workpiece materials are machined through the accumulation of small brittle fractures generated by the impacts of abrasive grains. Therefore, it becomes difficult to obtain a smooth machined surface. In the proposed Electrorheological Fluid-assisted ultrasonic machining (ER Fluid-assisted USM), the behavior of abrasive grains is controlled using the effect of dielectrophoretic force acting on the abrasive grains and the ER effect. The behavior of the abrasive grains can be controlled by changing the electric field distribution. In the present paper, the shape and position of the auxiliary electrode are arranged in order to control the abrasive grains to the side surface of the micro rectangular tool. By positioning the auxiliary electrode parallel to the micro rectangular tool, it becomes possible to concentrate abrasive grains to the side surface of the micro rectangular tool. Smoothing of the side surface of the workpiece by using the side surface of the micro rectangular tool is then investigated. As a result, the surface roughness of the side surface of the workpiece can be improved.

  • fabrication of high aspect ratio micro holes on hard brittle materials study on Electrorheological Fluid assisted micro ultrasonic machining
    Key Engineering Materials, 2008
    Co-Authors: Takumi Tateishi, Nobuhito Yoshihara, Jiwang Yan, Tsunemoto Kuriyagawa
    Abstract:

    Ultrasonic machining (USM) is an effective method for machining of hard brittle materials. In this process, the slurry is supplied to the gap between the workpiece and the ultrasonic vibrating tool, and the materials are removed by the impacts of the abrasive grains that are pressurized by an ultrasonic vibrating tool. The purpose of this research is to achieve precise and efficient microfabrication on hard brittle materials by USM. However, in the case of microfabrication, chipping which is generally observed around the edges of machined micro holes and grooves, deteriorates the machining accuracy. In addition, there is another problem in that the machining efficiency decreases with the progress of the machining. Electrorheological Fluid-assisted USM has been proposed as a countermeasure to these problems. In the present study, the problems and countermeasures associated with the machining of high-aspect ratio micro holes in hard brittle materials by Electrorheological Fluid-assisted USM are investigated. By positioning an auxiliary electrode under the workpiece, it becomes possible to keep the electric field high even when the machining depth becomes large. As a result, high-precision and high-aspect ratio micro holes can be machined on hard brittle materials.

  • an investigation of effective area in Electrorheological Fluid assisted polishing of tungsten carbide
    International Journal of Machine Tools & Manufacture, 2008
    Co-Authors: Lei Zhang, Yunwei Zhao, Tsunemoto Kuriyagawa
    Abstract:

    Electrorheological (ER) Fluid-assisted polishing is a novel polishing method for the finishing of micro-aspheric lens, dies and mirror. This paper investigates the effective area in the ER Fluid-assisted polishing of tungsten carbide, which is used as the die material for the mass production of micro-aspheric glass lens. The effective area is defined as the area in which the abrasive particles concentrated in the vicinity of the tool tip makes the effective material removal from the workpiece. The electric field strength applied between the tool and the workpiece is analysed. The interacting forces between particles suspended in the Electrorheological Fluid are calculated. An approach is proposed to predict the effective area and the experiments are conducted to confirm the validity of the proposed method.

  • Investigation into Electrorheological Fluid-assisted polishing
    International Journal of Machine Tools & Manufacture, 2005
    Co-Authors: Lei Zhang, Tsunemoto Kuriyagawa, Tsuyoshi Kaku, Ji Zhao
    Abstract:

    Electrorheological Fluid (ER Fluid) is a functional Fluid with the property that its viscosity can vary with the applied electric field strength. This paper investigates a polishing method using the Electrorheological Fluid, known as ER Fluid-assisted polishing, for the finishing of micro dies of tungsten carbide alloy, which are used for the mass production of micro aspheric glass lens. The machining principle of the ER Fluid-assisted polishing is introduced. By proper design of experiments based on a Taguchi orthogonal array and by multi-variable linear regression, empirical models are developed for evaluation of the effect of the process parameters on the material removal depth and surface roughness obtained in the ER Fluid-assisted polishing. Further experiments are conducted to confirm the validity of the developed statistical model by comparing the model predictions with the experimental results and meanwhile the influences of the process parameters on the polishing performance are revealed.

M Maleki - One of the best experts on this subject based on the ideXlab platform.

  • free vibration and forced harmonic response of an Electrorheological Fluid filled sandwich plate
    Smart Materials and Structures, 2009
    Co-Authors: Seyyed M. Hasheminejad, M Maleki
    Abstract:

    A dynamic model for the electric field-dependent steady-state vibrational response of a rectangular sandwich plate with a tunable Electrorheological Fluid (ERF) interlayer, subjected to a general harmonic transverse excitation, is developed. Hamilton's principle and the classical thin plate theory are applied to derive a set of fully coupled dynamic equations of motion along with the associated general boundary conditions. Assuming simply-supported edge conditions, the displacement components of the ERF-based sandwich plate are postulated by means of generalized double Fourier series with frequency-dependent coefficients. The natural frequencies and modal loss factors are subsequently determined by solving a complex eigenvalue problem. Analytical solutions are also obtained for the forced vibration characteristics of the adaptive structure under different external transverse excitations of varying frequency (0–300 Hz) and applied electric field strength (0–3.5 kV mm−1). Primary attention is focused on the effects of electric field magnitude, geometric aspect ratio, loading type, and ER core layer thickness on the dynamic characteristics of the sandwich plate. In addition, an effort is made to find the optimal electric field which yields minimized vibration amplitude for each excitation frequency. Limiting cases are considered and good agreements with the numerical solutions available in the literature are obtained.