Viscosity Of Electrorheological Fluids Research Articles

Efficient Electrorheological Technology for Materials, Energy, and Mechanical Engineering: From Mechanisms to Applications

Electrorheological (ER) technology is an advanced technology based on ER effects. The most common material in ER technology is an electrorheological fluid (ERF), which is a type of smart soft material. The viscosity of ERF is reversibly adjustable by an applied electric field. A new type of electroresponsive soft material, electrorheological elastomer (ERE), which is a derivative of ERFs, has attracted wide attention due to its advantages of not precipitating and easy packaging. ER materials are widely applied in mechanical engineering due to their reversibly tunable characteristics, fast response, and low energy consumption. In addition to basic ER material fabrication and application, ER technology is also used in energy material preparation, oil transportation, and energy storage. The application of ER technology in the energy field provides a good example of the potential applications of ER technology in other fields. This article systematically summarizes the research status and future development prospects of ER technology in materials, energy, and mechanical engineering from the mechanism to application, combined with the latest research results.

Nano titanium dioxide particles modified with poly(lauryl methacrylate) and its electrorheological and electrophoretic behavior

In this paper, we reported a new non-aqueous electrorheological (ER) fluid structured by TiO2 nano-particle modified poly(lauryl methacrylate) (PLMA/TiO2) dispersed in low viscosity isoparaffin and studied its electrorheological behaviors. Moreover, the ER fluid was applied to electrophoretic display at the first time. PLMA/TiO2 particles were prepared via graft copolymerization using γ-methacryloxypropyltrimethoxysilane and lauryl methacrylate, successively. The thickness of the cladding layer of nano titanium dioxide surface was about 2.9nm. When an external electric field was applied to this dispersed system, from 0 to 4.5kV/mm, the ER fluid showed a good rheological property and the viscosity of ER fluid was increased from 20 to 160mPas. The shear stress strengthened with PLMA/TiO2 particles weight fraction increase in dispersed system. As a white medium, the ER fluid was mixed with carbon black to prepare a micro-cup electrophoretic display device, which could successfully realize electrophoretic display for white and black state under an electric field. The maximum contrast ratio of the micro-cup device was 6.2, and response time was 288ms, and the clock micro-cup device could maintain display state than 24h in the absence of electric fields.

Vibration Control of Oscillating System Based on Governing Visco-Elastic Characteristics of Absorber by Means of External Electric Signal

Electro-rheological fluids (ERF) allow us to create «smart» devices. One of the basic directions of application of such materials is damping in oscillating systems. This work describes simulation model and offers the results of experimental research by rheological properties and damping characteristic of ERF. Control signal is defined by electric field intensity, which is changed within the bounds of 0…0.5 kV/mm. Amplitude of oscillation – up to 5 mm, oscillation frequency is modified within the bounds of 0.5…5 Hz. The logarithmic damping decrement and natural oscillation frequency of oscillating system, shear stress and viscosity of ERF are determined.

Electric field controlled flow behaviour of electrorheological fluid

The main purpose of the present study is to demonstrate the electric field controlled flow behaviour of electrorheological (ER) fluid. We have investigated the relation between the electric field and the change in the viscosity of electrorheological fluids. Different kinds of suspensions are used to search for the proper combination ER fluid for applying in a motor mount. A rotational viscometer is used to get how the viscosity depends on temperature and a special device to measure the effect of electric fields up to 1.8 kVmm-1.

Study of electrorheological sensitivity of suspensions based on hydrated aluminum oxides

The electrorheological fluids with the disperse phase formed by the particles of hydrated aluminum oxides prepared by the chemical precipitation from aluminum-containing solutions and subjected to heat treatment at different temperatures are studied. It is shown that the electrorheological activity of suspensions depends on the chemical and phase compositions of the dispersed phase. The influence of water, whose different forms comprise hydrated aluminum oxides, on the manifestation of the electrorheological effect of suspensions is estimated. It is established that the maximum gain in the effective viscosity of electrorheological fluids is related with water molecules forming hydrogen bonds in the interlayer space of the boehmite lattice.

Dynamic characteristics and optimization design for disc-shape electro-rheological actuator

A disc-shape electro-rheological actuator was developed. The torque generated by a pair of rotary discs consists of two components: the torque from the viscosity of electro-rheological fluid(ERF) and the torque owing to the field-dependent yield shear stress. The former contributes to the viscous power loss. Changing the application of electric field between the two discs, the output torque of ER actuator can be controlled to amplify the torque of input signal to overcome the load and friction. Relationships between the main structure parameters, the dynamic characteristics of the device, the physical properties of ERF and the torque transmission, range of speed regulation, power loss, stiffness of system were discussed. A multi-object programming model was set up for the optimization design. Experimental simulations with step and pulse signals were presented.

ER 유체의 채널유동에 대한 직접수치해석

Steady flow of an ER (electro-rheological) fluid in a two-dimensional electrode channel is studied by using FEM. Hydrodynamic interactions between the particles and the fluid are calculated by solving the Navier-Stokes equation combined with the equation of motion for each particle, where the multi-body electrostatic interaction is described by using point-dipole model. Motion of the particles in the ER fluid is elucidated in conjunction with the mechanisms of the flow resistance and the increase of viscosity. The ER effects have been studied by varying the Mason number and volume fraction of particles. These parameters have an influence on the formation of the chains resulting in the changes of the fluid velocity and the effective viscosity of ER fluids.

Investigations on Zeolite-Based ER Fluids Supported by Experimental Design

The application of experimental design for determining the influence of various parameters on rheological properties of electrorheological (ER) fluids is demonstrated. Such statistical methods allow the quantitative determination of parameter effects even in the presence of considerable property fluctuations of the ER fluid as well as the calculation of interactions between the parameter effects. They thus provide a powerful optimization tool. Investigations have been performed on ER fluids containing particles of zeolite A in silicone oil. The influence of zeolite content, oil viscosity, particle size, cation composition and ER fluid temperature on the viscosity of ER fluids with and without electric field has been studied. In addition to the main effects of the parameters interactions between them also play a considerable role. The ratio of ER fluid viscosities with and without field, respectively, decreases with rising oil viscosity and increases with temperature. The larger value of the ratio for ER fluids with smaller particles is referred to different particle structures. Results of parameter effects on viscosity of the ER fluid in electric fields depend on the shear rate. Cation exchange of sodium to potassium has only a minor influence on ER activity. This result is compared with cation exchange with calcium, by which ER activity is drastically diminished. The loss of activity can be related to the occupation of different cation sites in zeolite A.

The electrorheological performance of the particle materials adsorbed with strong rare earth electrolyte

The strong rare earth (RE) electrolytes-RE(ClO 4) 3, RE(NO 3) 3 and RECl 3 are adsorbed by the diatom earth (de), respectively and are dispersed in silicone oil. The electrorheological (ER) behavior of these electrorheological fluids (ERF) is tested at room temperature under d.c. field. The results show that the ER performance of the particle material may be changed with the rare earth electrolyte on the surface of the particles. The ER activity of the material can increase or decrease or disappear with the change of rare earth content (weight fraction) in the particles. The ER effect is strongly influenced by the ERF concentration. When the ERF concentration is beyond a certain value, the ER effect can disappear and the viscosity of ERF can decrease with the increase of electric field strength (E). The contribution of coordinated water with RE 3+ to ER effect is negligible.

Response time and viscosity of electrorheological fluids

The electrorheological effect is characterized by an increase in viscosity of two to three orders of magnitude when an electric field is applied. This feature opens a variety of potential applications for electromechanical devices. However, for practical applications, it is important to know the required time to reach the effective or working viscosity of the system. In fact, in a good electrorheological fluid (ERF), the response time is expected to be as rapid as a few milliseconds. Neverheless, no agreement has been reached in the literature on either what response time in ERFs really means or how to measure this quantity experimentally. Accordingly, a mechanical measurement of the characteristic times (or time constants) of different ERFs, both commercial and laboratory made, is presented, aiming to determine under which conditions a steady viscosity state is reached in every case. Suspensions of silica particles ( in diameter) in various dielectric fluids with different permitivities were prepared, to study the effect of these variables on the mechanical response of the system. The experiments were performed by using a modified torsion cell of a universal mechanical testing instrument.