Electrorheological Suspensions Research Articles

Effects of promoter and dedoping process on electrorheological response of polyaniline-graft-chitosan copolymer

In this study, electrorheological (ER) properties of biodegradable and conducting polyaniline-graft-chitosan (PAni-g-CS) copolymer particles were investigated. For this purpose, PAni and PAni-g-CS particles were synthesized by using in situ oxidative radicalic polymerization method. At first, PAni and PAni-g-CS/silicone oil (SO) ER suspensions (15% V/V) were subjected to external electric field and they exhibited low ER activity. When the external electric field strengths ([Formula: see text] were increased, both the suspensions showed electrical breakdown. Therefore, virgin PAni and PAni-g-CS were first subjected to dedoping process by treating with 1.0 M NaOH(aq) and non-ionic surfactant Triton X-100 (T-X) surfactant to enhance the expected ER activity and prevent the electrical breakdown. But we observed that the addition of T-X as promoter had no significant effect on the ER activity. On the other hand, electric filed-induced viscosities of both the suspensions were observed to enhance after the dedoping (DD) process and electrical breakdown prohibited. After the DD process, DD PAni-g-CS/SO ER system exhibited the highest electric field-induced viscosity by reaching 400[Formula: see text]Pa[Formula: see text]⋅[Formula: see text]s at [Formula: see text][Formula: see text]kV/mm. The highest ER efficiency was also obtained for DD PAni-g-CS/SO system at 15% (V/V) as 79. Additionally, typical shear thinning non-Newtonian viscoelastic behavior was observed under externally applied E. The conduction model of DD PAni-g-CS/SO system was determined to well fit the conduction model by showing a slope of [Formula: see text] calculated from the E vb. yield stress graph. In conclusion, conducting and biodegradable-dedoped PAni-g-CS particles would be a good candidate for potential ER applications as dry-based ER materials having high colloidal stability of 76%.

Fractional-order model-based robust identification for a vehicle semi-active electro-rheological suspension system

Fractional-order model-based robust identification for a vehicle semi-active electro-rheological suspension system

Fractional-order model-based robust identification for a vehicle semi-active electro-rheological suspension system

Fractional-order model-based robust identification for a vehicle semi-active electro-rheological suspension system

Electrorheological effect of suspensions containing mixed size of poly(ionic liquid) microspheres

In this paper, the electrorheological (ER) effect of suspensions containing mixed size of poly(ionic liquid) (PIL) microspheres were studied by combining experiment and molecular dynamics simulation. The PIL microspheres with two particle sizes were prepared via a cooling-assisted phase separation method. The PIL microspheres were dispersed in silicone oil to form five kinds of suspensions with different volume ratios of large and small at a fixed particle volume fraction. The ER effect of these suspensions was measured by a rheometer. We established ER suspension models for five suspensions and simulated the rheological curves of the ER suspensions using molecular dynamics-stochastic rotation dynamics method. Both experiment and simulation results showed that the ER effect of suspensions containing mixed size of PIL microspheres was lower than that of suspensions containing uniform size of PIL microspheres. The reasons for the influence of mixed particle size on ER effect were analyzed through the three-dimensional visualization simulation results.

Synthesis of polystyrene/poly(o-anisidine) core/shell structured microparticle and its electrorheological behavior

We fabricated core/shell typed semiconducting poly(o-anisidine) (POA) coated polystyrene (PS) composite microspheres and used them as an electrorheological (ER) material. Micro-spherical PS seeds were initially fabricated through a dispersion polymerization method, and the semiconducting POA was coated onto the PS seeds through a chemical oxidation polymerization technique. Uniform coating of the POA onto the PS particles was confirmed via morphology analysis. Their chemical structures and thermal behaviors were identified using Fourier transform infrared spectroscopy and thermogravimetric analysis, respectively. Using a rotational rheometer, PS/POA based ER fluid (5 vol%) exhibited a yield stress of about 72 Pa under an electric field strength of 2.5 kV/mm. Over the range of electric field strength, both dynamic and elastic yield stresses grew in proportion to the power of 1.5 of the electric field strength. Dielectric properties of the ER suspension were also found to be correlated with its ER properties.

Manganese Oxide Loaded Carbon Fiber for Solar Energy Harvesting and Oil Decomposition

In this work, a manganese oxide electrode, containing carbon nanofiber composites (MnO2/CNF), has been made through electrospinning, oxidization, and partial carbonization high-temperature treatment. Scanning electron microscopy (SEM) was used to observe the morphology of the nanofiber and analyze the composition of the fiber. The fiber size range and element distribution were determined. The oxide nanoparticles were modeled as electrorheological suspensions in the polyacrylonitrile polymer solution during electrospinning. The dielectrophoretic behavior of the particles subjected to non-uniform electric fields were analyzed and the motion of the oxide particles under the actions from fluctuating electric fields was investigated to explain the sporadic distribution of nanoparticles within the composite nanofibers. A photoactive anode was made from the composite nanofiber and the decomposition of spilled oil was performed under sunlight illumination. It was observed that the manganese oxide containing carbon nanofiber composite electrode can generate electricity and clean the spilled oil under sunlight. Both energy conversion and environment cleaning concepts were demonstrated.

Real-time Damper Force Estimation for Automotive Suspension

The real-time knowledge of the damper force is of paramount importance in controlling and diagnosing automotive suspension systems. This study presents a generalized H2/LPV observer for damper force estimation of a semi-active electro-rheological (ER) suspension system. First, an extended quarter-car model augmented with the nonlinear and dynamical model of the semi-active suspension system is written into the quasi-LPV formulation. Then, the damper force estimation method is developed through a generalized H2/LPV observer whose objective is to handle the impact of unknown road disturbances and sensor noise on the estimation errors of the state variables thanks to the H2 norm. The measured sprung and unsprung mass accelerations of the quarter-car system are used as inputs for the observer. The proposed approach is simulated with validated model of the 1/5-scaled real vehicle testbed of GIPSA-lab. Simulation results show the performance of the estimation method against unknown disturbances, emphasizing the effectiveness of the damper force estimation in real time.

Non Linear Parameter Varying Observer based on Descriptor Modeling for Damper Fault Estimation

This paper proposes an H∞ Non Linear Parameter Varying (NLPV) observer for fault estimation in semi-active Electro-Rheological (ER) suspensions. The damper fault (a loss-of-efficiency factor) is modeled as a lost force of unknown/free dynamics to be estimated. Thanks to the parameter-dependent descriptor-form system modeling, there is no assumption made on the fault dynamics, thus making this method applicable to all considered types of damper faults. The nonlinearity in the damper model is bounded by its Lipschitz property, while the road disturbance and the measurement noise are handled using the H∞ condition. The observer is parameterized and then designed by solving Linear Matrix Inequalities (LMIs) and is implemented in a polytopic gain scheduling approach. Synthesis results including Bode plots and simulations illustrate the method in both the frequency and the time domains.

Emerging approaches for nonlinear parameter varying systems

Emerging approaches for nonlinear parameter varying systems

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.

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.

Relationship Between Viscosity and Fine Current of Electrorheological Suspension, Toward Prediction of the Inner Structure

We analyzed a relationship between the viscosity and fine current of the ER suspension aiming for an estimation of the inner structure. This study aimed at an estimation of the inner structure formation via the fine current pass through the suspension. Viscosity and electrical current through electrodes were measured using similar apparatuses, and the relationship between the viscosity and fine current was investigated. The ER suspension was prepared by adding silica particles of 0.5 μm diameter to silicone oil of 0.291 Pa˙s viscosity. The solid volume fraction was 0.20. The voltage was varied from 0 to 1.5 kV/mm. The viscosity of the ER suspension was measured by a falling time in a rectangular tube. As a result, the fine current was found to correlate with the viscosity of the ER suspension. It indicated the possibility that the inner structure of the ER suspension can be estimated using the fine current through the ER suspension. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Preparation and Electrorheological Properties of Peanut‐Like Hollow Core–Shell Structure TiO2@SiO2 Nanoparticles

Although titanium oxide has a high dielectric constant, ordinary titanium oxides are not a good electrorheological (ER) fluid material. Herein, hollow peanut‐like titanium oxide spheres are synthesized by hydrothermal method, and then coated with silicon oxide to form core–shell hollow TiO2@SiO2 spheres. The structure is characterized by different methods, and the TiO2@SiO2 composite particles are dispersed in silicone oil to prepare an ER suspension. The ER effect of 10% TiO2@SiO2‐based ER fluid under different electric field strengths is tested, and its performance is analyzed. The results show that the coated particles significantly enhance the current meter performance. The shear stress value exceeds 200 Pa at an electric field strength of 3.0 kV mm−1. The shear stress, shear viscosity, switching effect, and dielectric behavior of the base ER fluid are studied. And, the cause of this strong ER effect is studied. In the end, it is found that TiO2@SiO2 peanut‐shaped composite core–shell particles have a good ER effect and which is a kind of ER candidate material with simple preparation and development prospect.

Effect of a temperature threshold on the electrorheological performance of ionic liquid crystal polyanilines

A series of ionic liquid crystal polyanilines (ILCPs) electrorheological (ER) compounds were synthesized by use of polyaniline, naphthalene disulfonic acid and pyridinyl-containing mesogen. The chemical structure, thermal property, morphology, liquid-crystalline behavior, dielectric property and ER effect of the ILCPs-based ER fluids were characterized by use of various experimental techniques. The synthesized ILCPs displayed nematic liquid-crystalline phase, and the different mesogens played a determinant role in the liquid crystal behavior. The experimental results about dielectric property of the ILCPs suggested that both dielectric constant and dielectric loss increase with raising the temperature, showing a sudden change around glass-transition temperature. The ILCPs-based ER fluids contained an integrated character of liquid crystal, poly(ionic liquid) and polyaniline-base ER suspensions. These characteristics had strong dependence on operating temperature, and a temperature threshold was observed on the ER performance. The shear stress of the ER fluids increased abnormally near glass-transition temperature, which was due to the synergetic effect between the mesogenic orientation and the stretched polyaniline droplets induced by the electric field.

Liquid-crystalline behaviour and electrorheological effect of phthalocyanine-based ionic liquid crystals

ABSTRACT Series of phthalocyanine-based ionic liquid crystals (PILCs) electrorheological (ER) materials were synthesised using brominated polyesters and a phthalocyanine (Pc)-containing monomer, and the chemical structure, liquid-crystalline behaviour, dielectric property and ER performance were characterised. All PILCs showed nematic phase, but some PILCs with more phthalocyanine moieties showed discotic hexagonal columnar mesophase. The dielectric permittivity increase with the increasing temperatures, but decrease with the increase of frequency for these PILCs. The PILCs-based electrorheological fluids (ERFs) contained an integrated character of liquid crystal, poly(ionic liquid) and Pc-base ER suspensions. The ERFs were made by PILC particles and silicone oil, and the ER effect was investigated at controlled test conditions including concentration, electric field strength, temperature and shear rate. When the ERFs were applied an external electric field strength, the shear stress increased instantly, and they showed non-Newtonian behaviour. At the same conditions, the ER effect improved as the measured temperature raised. Furthermore, the ER effect increased with the increase of ionic Pc moieties in the polymer systems. These results were originated from the synergetic effect among the mesogenic orientation and rearrangement of ionic Pc droplets induced by the electric field, forming an alignment-aggregated fibrillation chain.

Sub‐optimal recursively feasible Linear Parameter‐Varying predictive algorithm for semi‐active suspension control

This study proposes an algorithm to enhance the comfort of passengers in a vehicle with semi-active suspensions. The vertical dynamics of the car are represented through a quasi-linear parameter-varying (qLPV) model. The scheme resides in solving a set-constrained model predictive control (MPC) problem, embedding a comfort performance index to the MPC optimisation function. Its sub-optimality resides in the fact that the MPC is synthesised considering a frozen guess for the evolution of the qLPV scheduling parameters along the horizon. Assuming bounds on the variation rates of the qLPV scheduling parameters, the method enables a replacement of the original complex non-linear optimisation by a much simpler quadratic program (QP). This QP uses a Lyapunov-decreasing cost and set-based terminal ingredients, which guarantee that the domain of attraction of the controller is enlarged and that recursive feasibility can be maintained. The study ends with successful realistic non-linear simulations of a one-fifth-scaled car with electro-rheological suspensions, for which the proposed method is tested and compared with other optimal controllers (Linear Quadratic Regulator (LQR) and linear MPC). The results illustrate the overall good operation of the vehicle; the comfort of the passengers is substantially improved, as measured through time- and frequency-domain indexes.

Electrorheological Behavior of Suspensions of Polyimide-Based on the Sodium Salt of 2,5-Diaminobenzenesulfonic Acid

Electrorheological suspensions (ERS) of polyimide particles with organoelement fragments from the sodium salt of 2,5-diaminobenzene sulfonic acid were obtained for the first time. Their rheological and electrorheological characteristics, their dependence on the parameters of deformation, and the intensity of the external electric field were studied. It was found that the ERS of PI-Na polyimide particles have a significant electrorheological response. Solid-polyimide materials were previously studied using a scanning electron microscope. The effect of the polyimide concentration on the properties of the solution was studied by spectrophotometry. It was shown that polyimide suspension is a result of increasing intensity as the electric field changes the flow type from Newtonian to pseudoplastic due to polarization of the particles and formation of the chain structures along the power lines of the electric field. The influence of temperature on the change of rheological and electrorheological properties of a polyimide ERS in constant electric fields was investigated.

Electrorheological properties of polyimide nanoparticles suspensions

Suspensions of polyimide particles were obtained, in which 2,5-diaminobenzenesulfonic acid was used as a diamine component. Their electrorheological properties in a nonconducting medium were studied depending on the parameters of deformation and the intensity of the external electric field. It is established that the electro-rheological suspensions obtained based on particles of polyimide PI-I–PI-IV have a powerful electro-rheological response, ten times higher than the electro-rheological effect of suspensions based on traditional micro-sized particles of the dispersed phase.

Highly stable and efficient electrorheological suspensions with hydrophobic interaction

HypothesisElectrorheological fluid (ERF) is a kind of suspension or colloid composed of fine particles and insulating oil as continuous phase. The second miscible liquid phase with less affinity to the particles than the continuous phase is expected to influence particles aggregation, assembly and spanning mesostructures. Hence, it should be possible to tune the rheological and electrorheological properties and stability by the addition of second miscible liquid with different chain length and substituents. ExperimentsWe developed a giant ERF (GERF) with a binary liquid phase (BLP) by the addition of alkane to the silicone oil continuous phase. We studied the shear stress and viscosity under different shear rates, thixotropy and particle size distributions of these suspensions and characterized the concentration variation of GERFs under quiescent conditions by measuring the backscattering light intensity variation through vertical scanning. FindingsThe dispersed particle size distribution is broadened, which produces higher static yield stress and lower zero-field viscosity than those of a single-liquid-phase GERF. The ER efficiency is much higher with the addition of alkane, reaching 10656, which is 1.8 times larger than that of single-liquid-phase suspensions. We performed 100-day stability testing and found that the GERF with 1-phenyldodecane showed excellent stability and performance.

Rheological analysis of titanium dioxide nano-whisker based electrorheological fluids

Understanding yield stress of electrorheological (ER) fluids becomes important for not only development of advanced ER materials but also their engineering applications. This study reanalyzed dynamic yield stresses of both titanium dioxide nano-whisker- and titanium dioxide nano-particle-based ER suspensions under an input electrical field, based on the universal yield stress function proposed. The experimental data was plotted well to a single line by the scaled universal yield stress function via a deduced critical electrical field value which divides electric field dependent yield stress region with a slope of 1.5 from that with 2.0 of polarization mechanism.