Electrorheological Research Articles

Monodisperse semiconducting poly(N-methylaniline) microspheres and their electrorheological response

Monodisperse semiconducting poly(N-methylaniline) (PNMA) microspheres with a suitable electrical conductivity were fabricated using a chemical oxidation process and employed in an electrorheological (ER) suspension. Morphological image of the synthesized PNMA microsphere was assessed via scanning electron microscope and transmission electron microscope. Its chemical composition and thermal behavior were determined using Fourier-transform infrared and thermal gravimetric analysis, respectively. Chain-like structure formation under an input electric field in ER fluid containing silicone oil and 10 wt% PNMA microspheres was observed directly with optical microscopy. Viscoelastic characteristics of the ER fluid under an input electric field were evaluated with a rotational rheometer. Yield stress with a power exponent of 1.5 was observed, along with typical solid-like property under electric field. Dielectric behavior of the ER suspension measured was also found to be closely associated with its ER behavior.

Numerical simulation of impact sound transmission control across a smart hybrid double floor system equipped with a genetically-optimized NES absorber

An idealized detailed 2D formulation is presented for suppression of transient impact sound transmission across a hybrid smart double-leaf sandwich beam (floor-ceiling) structure into a rectangular (receiving) room with ideally flat and rigid walls. The smart double wall structure, which is mechanically inter-connected at an arbitrary point with a lightweight nonlinear energy sink (NES) absorber, incorporates spatially distributed and electrically independent non-collocated semiactive (electro-rheological fluid- or ERF-incorporated) and fully-active (piezoceramic- or PZT-incorporated) actuator layers functioning in a closed loop control framework. Extensive time-domain numerical simulations initially calculate both the uncontrolled and controlled transient acoustic pressure fields in absence of the dynamic vibration absorber for four separate settings of the active (PZT-) and semiactive (ERF-) actuation elements. Subsequently, the remarkable performance of the GA-optimized hybrid smart active/semi-active/passive (PZT/ERF/NES) configuration, which benefits from the multi-mode targeted energy transfer (TET) mechanism of the NES, in significant broadband (low frequency) attenuation of the transmitted shock energy with a much lower actuator energy demand, is demonstrated. Furthermore, some important aspects of the transient fluid-structure interaction (TFSI) control problem like weakening of the acoustic shock focusing effects (focal zones) within the source room are illustrated through selected early-to-late-times 2D images and animations of the cavity pressure fields. Limiting situations are studied and correctness of the derivations is established against accessible data in addition to numerical (FEM) simulations.

Selected papers from the 17th International Conference on Electrorheological Fluids and Magnetorheological Suspensions (ERMR2019, Part 1)

Selected papers from the 17th International Conference on Electrorheological Fluids and Magnetorheological Suspensions (ERMR2019, Part 1)

Phase transition in electrorheological plasmas

AbstractApplying an external electric AC field to a dusty plasma, the micro‐particles arrange in strings or chains. In analogy to electrorheological fluids, such a system is called electrorheological plasma. Turning gradually the AC field into a DC field, the string formation is diminished until it vanishes completely in the DC case. In this way, a cross‐over transition from a string‐like to an isotropic micro‐particle many‐body system can be investigated. Experimental investigations of electrorheological plasmas are performed under microgravity conditions in parabolic flights. For analysing the image data, a supervised machine learning code was developed and a continuous cross over was found. A molecular dynamics simulation showed qualitatively similar results but also some deviations from the experimental results.

A nonlinear parameter varying observer for real‐time damper force estimation of an automotive electro‐rheological suspension system

AbstractThis paper proposes a nonlinear parameter varying (NLPV) observer to estimate, in real‐time, the damper force of an electrorheological (ER) damper in a road vehicle suspension system. The objectives are to minimize the effects of bounded unknown road profile disturbances and measurement noises on the estimation errors in the framework. Furthermore, the nonlinearity coming from the damper model (and considered in the observer formulation) is handled through a Lipschitz condition. The observer inputs are data given by two low‐cost sensors (two accelerometers data from the sprung mass and the unsprung mass). For performance assessment, the observer is implemented on a 1/5‐scaled real vehicle testbench of GIPSA‐lab, namely INOVE (see www.gipsa‐lab.fr/projet/inove). Both simulation and experimental results demonstrate the effectiveness of the proposed observer in terms of the ability to estimate the damper force in real‐time and to minimize the effects of measurement noises and road disturbances.

A multi-DOF soft microactuator integrated with flexible electro-rheological microvalves using an alternating pressure source

For advanced microrobots such as an in-pipe working microrobot with dexterous micromanipulators, a novel multi-degree of freedom (DOF) soft microactuator integrated with flexible electro-rheological microvalves (FERVs) using an alternating pressure source was proposed and developed. The concept of the proposed actuator includes a series connection of multiple one-DOF microactuator units, built-in FERVs, and an alternating pressure system. The one-DOF soft microactuator unit consists of a bending fluidic actuator part and the FERVs. The FERV made from flexible materials controls electro-rheological fluid (ERF) flow by its viscosity change with the electric field applied through fixed electrodes. The alternating pressure of the ERF is supplied with only one pipe and rectified with the synchronously on/off-controlled FERVs. The benefits of the proposed actuator are (a) compact design with built-in FERVs and the alternating pressure system, (b) multi-DOF actuator with simple structure, and (c) closed system suitable for independent microrobots. In this paper, as a basic module, a 20 mm long two-DOF soft microactuator with two actuator units was developed. Through simulation, the length ratio of the one-DOF soft microactuator units were determined. The material of the fluidic chambers was selected by fabricating and testing the bending fluidic actuator parts. Then the designed microactuator was successfully fabricated using MEMS technologies. Through experiments, the tip displacements, the response, and the output forces were clarified. The two-DOF motion was realized and the validity of the proposed actuator was confirmed.

Ionic-liquid-modified TiO2 spheres and their enhanced electrorheological responses

An ionic liquid functionalised silane agent, 1-(3-triethoxysilylpropyl)-3-methylimidazolium chloride (TESPM-IL), was prepared and used to fabricate ionic liquid (IL)-grafted titanium dioxide (IL-TiO2) spheres via a sol-gel process. Thermogravimetric analysis and Fourier transform infrared spectroscopy confirmed that TESPM-IL was attached to TiO2 spheres. Morphologies of the IL-TiO2 spheres were observed by scanning electron microscopy and transmission electron microscopy, indicating the rough surface and smaller size of the IL-TiO2 particles caused by the modification of TESPM-IL. The IL-TiO2 particles were applied as a new dispersed-phase material of electrorheological (ER) fluids. The ER effect of IL-TiO2 particles was studied and compared with that of pure TiO2 particles. It was found that, upon the introduction of TESPM-IL, both yield stress and storage modulus of the IL-TiO2 ER fluid were enhanced significantly, thus improving the ER effect of TiO2- or inorganic-based ER materials effectively. Dielectric analysis was also used to observe the interfacial polarization process of the particles, which confirmed the effect of the IL layer on the surface of the TiO2 particles.

Induced permittivity increment of electrorheological fluids in an applied electric field in association with chain formation: A Brownian dynamics simulation study.

We report Brownian dynamics simulation results for the relative permittivity of electrorheological (ER) fluids in an applied electric field. The relative permittivity of an ER fluid can be calculated from the Clausius-Mosotti (CM) equation in the small applied field limit. When a strong field is applied, however, the ER spheres are organized into chains and assemblies of chains in which case the ER spheres are polarized not only by the external field but by each other. This manifests itself in an enhanced dielectric response, e.g., in an increase in the relative permittivity. The correction to the relative permittivity and the time dependence of this correction is simulated on the basis of a model in which the ER particles are represented as polarizable spheres. In this model, the spheres are also polarized by each other in addition to the applied field. Our results are qualitatively similar to those obtained by Horváth and Szalai experimentally [Phys. Rev. E 86, 061403 (2012)PLEEE81539-375510.1103/PhysRevE.86.061403]. We report characteristic time constants obtained from biexponential fits that can be associated with the formation of pairs and short chains as well as with the aggregation of chains. The electric field dependence of the induced dielectric increment reveals the same qualitative behavior that experiments did: three regions with different slopes corresponding to different aggregation processes are identified.

Silica-based ionogels containing imidazolium ionic liquids and their electrorheological responses at room and elevated temperatures

In this study, we report the electrorheological (ER) effects of silica-based ionogels containing imidazolium ionic liquids (ILs) when dispersed in silicone oil at different temperatures. The amount of IL agent used in the synthesis process of the silica-based ionogels by a sol-gel method significantly affected morphologies of the silica-based ionogels, resulting in particles with rough surface and agglomerations. This electric-field-tunable rheological properties of the ionogel-based ER fluids were closely related to the dosage of ILs used in the synthesis process. With a proper amount of IL, the ionogels of SiO2-IL-0.5, SiO2-IL-0.8 and SiO2-IL-1.0 showed enhanced ER effects under steady shear flow with an applied electric field compared with pristine SiO2; however, excessive ILs in ionogel (SiO2-IL-1.88) could reduce the ER effect of the ER fluid. More importantly, upon modification by IL, the SiO2-IL-0.8 ionogel exerted the highest ER effect which was stable in the temperature range of 25−120 °C, showing good applicability at high temperature.

Investigation of vibration damping properties of electroactive polyanthracene/silicone oil dispersions

Electrorheological (ER) fluids generate mechanical responses to applied electric field strength via changing their rheological properties from liquid to solid and vice-versa reversibly. As a result of this, ER fluids can be used in the industrial vibration damping systems. In order to increase applicability of ER fluids, it is necessary to understand electric field induced polarization and ER mechanism of different materials. Therefore, the aim of this study is to illuminate ER and vibration damping properties of polyanthracene (PAT), which is a new material for ER studies. PAT was synthesized from anthracene and characterized by several techniques namely: ATR-FTIR spectroscopy, particle size, SEM image, four-point probe conductivity, and magnetic susceptibility measurements. A series of PAT/silicone oil (SO) dispersions having various concentrations were prepared and subjected to dielectric and ER tests. Then, the colloidal stabilities of 20% PAT/SO and 20% PAT/SO/TritonX systems were determined. Dynamic viscoelastic data obtained by the oscillation tests showed that viscous behavior was dominant under zero electric field, whereas elastic behavior was prevailing under external electric field strength and highlighting the vibration damping characteristics of PAT/SO dispersion. In the creep-recovery measurements, the highest %recovery was recorded to be 62% indicating potential industrial use of PAT/SO dispersion.

Multi-electrode layout design of electrorheological composite plates considering energy consumption in semi-active control

In the semi-active vibration control of structural systems, best control performance and low energy consumption both play important roles. This paper presents a new topology optimization method for the multi-electrode layout design of sandwich electrorheological (ER) plates considering limited energy consumption under different vibration conditions. In the proposed topology optimization model, the dynamic compliance under specified harmonic excitation is taken as the objective function, and a constraint of the maximum allowable energy consumption is considered. The frequency response analysis is implemented with finite element discretization, and the sensitivity analysis scheme of the control energy consumption for the design variables is derived with the adjoint-variable method. Numerical examples showed that optimal layouts of multi-electrodes could be obtained with different energy consumption requirements and loading conditions by using the proposed method. The excellent performance of vibration control could be achieved by only varying the voltage distribution of ERs.

Magnetite/Poly(ortho-anisidine) Composite Particles and Their Electrorheological Response.

Magnetic and semiconducting Fe3O4/poly(o-anisidine) (POA) core/shell composite particles were fabricated by an oxidation process using Fe3O4 synthesized separately. The dispersion stability in a liquid medium and the electrical conductivity of synthesized particles were improved because of the conductive POA polymeric shell. The morphological, microstructural, compositional/elemental, and thermal behaviors of the particles were characterized using SEM with energy dispersive X-ray spectroscopy, TEM, XRD, and thermogravimetric analysis, respectively. A smart electro-magneto-rheological suspension containing Fe3O4/POA particles with two functionalities, magnetism and conductivity, was prepared. Its electrorheological properties were investigated at different electric field strengths using a rotational rheometer. Without an electric field, the sample demonstrated typical Newtonian fluid behavior, as expected. However, while under the electric field, it exhibited a solid-like behavior, and the dynamic (or elastic) yield stress of the ER fluid increased linearly as a function of the electric field strength in a power-law function with an index of 2.0, following the polarization mechanism.

The influence of synthesis conditions on the electrorheological performance of iron(II) oxalate rod-like particles

This study investigates the influence of synthesis conditions of iron(II) oxalate particles on the particle morphology for their utilization in smart materials known as electrorheological (ER) fluids. Particle morphology has a significant impact on the ER behavior of the particles enabling their use in many unique practical applications. In this study, fifteen various iron(II) oxalate particles differing in synthesis conditions were prepared, out of which four variations were selected for an in depth investigation due to their promising morphology. The influence of synthesis conditions on the morphology of the resulted particles was evaluated by scanning electron microscopy analysis. An X-ray diffraction analysis was employed to confirm the dominant FeC2O4 · H2O phase presented in the synthesized particles. The ER suspensions consisted of the selected four iron(II) oxalate particles dispersed in silicone oil. An optical microscope and a rheometer, both operating under external electric field, enabled a precise and accurate investigation of the structure, the ER performance. Visual observation was used to evaluate the sedimentation stability of the suspension.

In situ X-ray analysis of montmorillonite suspensions in polydimethylsiloxane: Orientation in shear and electric field

The behavior of electrorheological fluids filled by particles with a high aspect ratio was studied in situ by X-ray scattering using special cell. An orientation phenomena of particles in suspensions of variously modified montmorillonites at low concentrations under electric field and shear stress was clearly observed. It has been revealed that the type of modifier in clay structure plays a crucial role for the particles orientation under electric field. The relationship between the electrorheological behavior of suspensions and the filler structuring was discovered. The paper discussed the reasons of different particles organization depending on external influence. Using a simple model, a road map of possible structural states of suspensions was proposed. The prospects of in situ X-ray studies to comprehending the mechanism of electrorheological effect have been shown.

On (p(x), q(x))‐Laplace equations in ℝN without Ambrosetti‐Rabinowitz condition

In the present work, we consider a (p(x), q(x))‐elliptic equation describing the behavior of a double‐phase anisotropic problem which has relevance in electrorheological fluid applications. The analysis leads to the existence of weak (nonnegative) solutions in the special case of potential terms with critical frequency and a superlinear reaction term. In order to prove the existence result, we combine critical point theory of mountain pass type with related topological and variational methods. Basically, the approach is variational, but we do not impose any Ambrosetti‐Rabinowitz type condition for the superlinearity of the reaction. More specifically, we apply the Euler‐Lagrange functional approach to the variational formulation of the above‐mentioned model problem. We note that we work in the whole space and so we have to consider non‐compact embeddings. This aspect constitutes an additional difficulty in our study.

Self-assembly, liquid crystalline behavior and electrorheological performance of phthalocyanine-contaning polysiloxanes

Series of phthalocyanine-based ionic liquid-crystalline polysiloxanes (ILCPs) were self-assembled by bromo-polysiloxanes and zinc tetraaminophthalocyanine, and their chemical structure, thermal and liquid-crystalline (LC) behavior were characterized by various experimental techniques. The ILCPs exhibited hexagonal columnar phase and SmA phase. The effects of ionic phthalocyanine content and LC phase on the dielectric properties including dielectric constant and dielectric loss were investigated, which was closely related to their electrorheological (ER) effect. The ILCPs-based ER fluids (ERFs) were prepared by the ILCPs and silicone oil, and the ER performance was investigated at controlled test conditions. The ER effect increased with the increase of ionic phthalocyanine moieties for these ERFs. Furthermore, the ER efficiency of the ERFs at 330 K was much higher than that at 300 K at the constant conditions. The real-time response experiments of the ERFs was performed by switching alternately turned on or off the electric field, illustrating a synergetic rearrangement and orientation of the LC mesogens and the ionic phthalocyanine moieties along the direction of the electric field. Moreover, the ERFs showed good sedimentation property due to good compatibility between ILCPs’ polysiloxane matrix and the polysiloxane-based silicon oil.

Preparation of Cellulose/Laponite Composite Particles and Their Enhanced Electrorheological Responses.

Cellulose, as a natural polymer with an abundant source, has been widely used in many fields including the electric field responsive medium that we are interested in. In this work, cellulose micron particles were applied as an electrorheological (ER) material. Because of the low ER effect of the raw cellulose, a composite particle of cellulose and Laponite was prepared via a dissolution–regeneration process. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to observe the morphologies and structures of the composite particles, which were different from pristine cellulose and Laponite, respectively. The ER performances of raw cellulose and the prepared composite were measured by an Anton Paar rotational rheometer. It was found that the ER properties of the composite were more superior to those of raw cellulose due to the flake-like shapes of the composite particles with rough surface. Moreover, the sedimentation stability of composite improves drastically, which means better suspension stability.

Stability of non-Newtonian fluid and electrorheological fluid mixed-type equation

In this paper, we consider a non-Newtonian fluid and electrorheological fluid mixed-type equation where p>1, and . The existence of weak solution is investigated by means of the parabolically regularized method. Due to , the stability of weak solution is established by choosing a suitable test function and the local stability is also discussed without any boundary value condition.

Is Chitosan the Promising Candidate for Filler in Nature-Friendly Electrorheological Fluids?

In this study, an electrorheological effect of the suspensions containing porous chitosan particles in olive oil in a wide range of electric fields is reported. Porous chitosan particles were produ...

Multiple solutions for a class of problems involving the p(x)-Laplacian operator

ABSTRACT In this paper we obtain an existence result for an wide class of problems involving variable exponents which are related to several applications in electrorheological fluids and image processing. Under additional conditions it is obtained the multiplicity of solutions. It is also presented examples of applicability of the results. The arguments are based on sub-supersolutions and appropriated estimates in the variable spaces setting.