Electrorheological Research Articles

Evaporation-assisted phase separation preparation and electrorheological effect of poly(ionic liquid) microspheres with dual and mixed counterions

We prepare poly(ionic liquid) (PIL) microspheres containing dual counterion and single counterion in a unitary unit via an evaporation-assisted phase separation method, and study the influence of the number and type of counterions on the electrorheological (ER) effect and dielectric properties of the PIL microspheres. The morphology and structure of PIL microspheres are characterized and the ER effect of PIL microspheres in insulating carrier liquid is measured under electric fields. It shows that when the type of counterions is identical, the dual-ion PIL (D-PIL) microspheres have a stronger ER effect than that of the single-ion PIL (S-PIL) microspheres. Dielectric spectra analysis indicates that D-PIL microspheres have higher interfacial polarization rate compared to S-PIL microspheres due to enhanced charge density and ion transport dynamics according to Raman spectra and activation energy analysis. This should be responsible for the stronger ER effect of D-PIL microspheres. However, when the type of counterions is different, the ER effect of D-PIL microspheres is largely reduced. This is because the mixed alkali effect of mixed counterions significantly increases the activation energy of ion transport and decreases conductivity and interfacial polarization rate of PIL microspheres containing mixed counterions. The result can provide a new understanding of structure-property relationship for PIL-based ER material design and preparation.

Electrorheological fluid–assisted ultrasonic polishing for IN625 additively manufactured surfaces

Electrorheological fluid–assisted ultrasonic polishing for IN625 additively manufactured surfaces

Vibration performance analysis of a self-energized damper composed of electrorheological fluid and piezoelectric ceramics

The damper composed of electrorheological fluids (ERF) and piezoelectric ceramics (PZT) is self-energized damper, which doesn’t need additional power supply and control system and has a certain adaptive damping effect on external load. This paper makes three improvements on the existing ERF-PZT self-energized damper. The symmetrical arrangement of PZT about central location is proposed and the voltage is generated during the entire vibration process. Then, the gas chamber is arranged on the top of the upper damping cavity, increasing the guide stroke of the piston rod and preventing the ERF particles from blocking the floating piston. Last, the lower damping hole is changed as arc channel to prevent the ERF particles from blocking the hole. Further, the mathematical model based on Bingham's rheological laws of ERF is established and simulated with MATLAB. The amplitude frequency characteristics, the damping force characteristics, and the vibration energy consumption are analyzed. The results show that the improved damper has less resonance amplitude and higher resonance frequency, larger damping force above the balance position, better self-energized-damping ability and larger vibration energy consumption. Therefore, the improved ERF-PZT self-energized damper has better vibration suppression performance.

Composites of Co-Doped Graphitic C3N4 Nanosheets and TiO2 Nanoparticles for Electrorheological Fluid Applications

Composites of Co-Doped Graphitic C₃N₄ Nanosheets and TiO₂ Nanoparticles for Electrorheological Fluid Applications

Electrorheological Fluids of GO/Graphene-Based Nanoplates.

Due to their unique anisotropic morphology and properties, graphene-based materials have received extensive attention in the field of smart materials. Recent studies show that graphene-based materials have potential application as a dispersed phase to develop high-performance electrorheological (ER) fluids, a kind of smart suspension whose viscosity and viscoelastic properties can be adjusted by external electric fields. However, pure graphene is not suitable for use as the dispersed phase of ER fluids due to the electric short circuit caused by its high electrical conductivity under electric fields. However, graphene oxide (GO) and graphene-based composites are suitable for use as the dispersed phase of ER fluids and show significantly enhanced property. In this review, we look critically at the latest developments of ER fluids based on GO and graphene-based composites, including their preparation, electrically tunable ER property, and dispersed stability. The mechanism behind enhanced ER property is discussed according to dielectric spectrum analysis. Finally, we also propose the remaining challenges and possible developments for the future outlook in this field.

On the static performance characteristics of ER fluid lubricated asymmetric journal bearing

The performance of a hole entry journal bearing with an asymmetrical arrangement of holes is examined in this paper using the finite element method. The lubricant utilised is electrorheological (ER) fluid, and orifice restrictors were used to control flow in each hole. Examined performance variables include lubrication pressure, lubricant film thickness, and bearing flow. The outcomes are contrasted with the Newtonian case. By altering the electric voltage, ER fluid has been used to provide very precise control of lubricant viscosity. When ER fluid driven bearings are compared to Newtonian lubricated bearings, higher pressure values are attained. Variable voltage was used to control the viscosity. At 400 V and 1200 V for W = 1.2, the increase in maximum pressure for the asymmetric hole entry design using ER fluid as the lubricant is calculated to be 8.3 % and 13.8 %, respectively. For the same amount of W, the percentage reduction in bearing flow is 2.5 % and 15.7 % at 400 and 1200 V, respectively.

Semi-conducting microspheres formed from glucose for semi-active electric field-responsive electrorheological systems.

In this study glucose particles were successfully transformed to conducting carbonaceous microspheres through sequential hydrothermal and thermal carbonization. The prepared carbonaceous particles were thereafter used as a dispersed phase in a novel electrorheological fluid. Due to significant enhancements of the conductivity and dielectric properties when compared with the glucose precursor, the prepared electrorheological fluid based on carbonaceous microspheres exhibited a yield stress of over 200 Pa at a particle concentration of 5 wt% at an electric field intensity of 3 kV mm-1, and overcomes recently published novel electrorheological fluids and others based on carbonized particles. In order to estimate the exact rheological parameters, the measured data were treated using a mathematical model Cho-Choi-Jhon, and the reproducibility and reversible possibility to control the viscosity of the novel prepared electrorheological fluid were confirmed through time dependence tests at various electric field intensities. Not only did this approach lead to carbonaceous conducting particles with high performance in electrorheology, but the yield after carbonization at 500 °C was also 60%. It was thus confirmed that unique carbonaceous conducting particles were prepared using a sustainable method giving high yields, and can be potentially used in many other applications where such carbonaceous particles are required.

高圧力駆動ERマイクロアクチュエータに関する研究

For power microrobots that work in narrow space such as inside of pipes of industrial plants, microactuators using ER microvalves that control ERF (electro-rheological fluid) flow due to the apparent viscosity change in electric fields (ER effect) have been investigated. Higher pressure can realize higher performance due to the decreased cross section of the hydraulic actuator and the decreased diameter of the pipes with lower flow rate for the same fluid power. However, the ER effect of liquid crystal type ERF is decreased when the shear rate exceeds the limit. Hence, in this study, we proposed and designed an ER microactuator considering the shear rate limit. Then we fabricated the ER microvalve using MEMS fabrication process. Finally, we clarified the characteristics of the ER microvalve, the rubber-tube microacuator, and the ER microactuator using the elements experimentally.

Stretchable and conformable variable stiffness device through an electrorheological fluid.

Stiffness variations extend creatures' functions and capabilities to deal with complex environments. In this study, we proposed an electrorheological fluid-based variable stiffness device, named VSERF, made up of soft materials. Our device is soft, thin, and stretchable so that it can conform to surfaces with complex morphologies. The stiffness of the VSERF device can be continuously, independently, and reversibly adjusted by applying an electric field. It achieves 14.8-times compressive stiffness variation and 3.5-times tangential stiffness variation when the electric field intensity increases from 0 V mm-1 to 750 V mm-1. The VSERF device is able to return to its initial shape after removing the external force and electric field, allowing it to be reused. The effects of stretching and bending on the device's capability of stiffness variations are investigated experimentally and the results show that the stiffness variation is unaffected by a stretching strain of up to 20% and a bending curvature of up to 50 m-1. Finally, we show that the VSERF device is capable of conforming to complex surfaces (coral stones, pencils, and 3D printed cubes) in its inactive state, hanging on them with a weight of up to 80 g (19 times of its own weight) in its active state, and detaching when the electric field is removed. The device's short-term and long-term stabilities are experimentally investigated as well. The demonstration of the VSERF's attaching and detaching ability shows that the stiffness-variation device's adaptability to complex environments can be improved.

Synthesis characterization and functional analysis of magneto rheological fluid – A critical review

Smart materials are stimuli-responsive materials, such as piezoelectric, shape memory alloys, electro-rheological fluid, and magneto-rheological fluid, that can be used to control vibrations. The technology using Magneto Rheological Fluid is known for its simplicity and intelligence in its operation. Because of the nonlinear nature of magneto-rheological (MR) dampers, establishing models that correctly capture their unique properties is one of the most difficult components of developing and achieving high performance. This paper also examines research gaps in constitutive modeling of MR fluids, highlights research paths, and offers recommendations for future research. Some noteworthy advancements in physical innovations, applications, and superiority of these devices are discussed in depth. The properties of MR dampers, their applications, benefits, limits, and future developments are discussed in this paper.

A Study on an Advanced Alternating Pressure System Using Particle Type Electro-Rheological Fluid

For power microrobots that perform power-needed tasks in narrow spaces, we have proposed an alternating pressure system using ER valves. The ER valve controls an ERF (electro-rheological fluid) flow with its increased viscosity due to an applied electric field. In the alternating pressure system, an alternating flow is rectified with synchronously switching ER valves and supplied to a soft actuator, which realizes smaller piping space for multiple actuators. In the conventional system, liquid crystal type ERF was used, however, the ER valve cannot be shut off, which caused internal leakage. In this study, we proposed an advanced alternating pressure system using particle type ERF that can shut off the ER valves rapidly. We investigated the characteristics through numerical simulations. Then we fabricated the advanced alternating pressure system and clarified its characteristics and effectiveness experimentally.

A comprehensive review on emerging trends in smart green building technologies and sustainable materials

The use of environmentally friendly materials in construction has become increasingly possible due to advancements in green technology. There are several sustainable materials derived from industrial waste that aid in reducing embodied energy and maximizing the use of renewable resources. Technology is the key to successful projects that advance green building. Various green building technologies with temperature reduction, wastewater systems, energy efficiency, photovoltaic powered cooling system, etc are represented in this paper. In green building, a building information model (BIM) and ontology are used to manage multi-disciplinary activities. SWRL and OWL models based on the Jess rule engine are combined to improve building efficiency. Sustainable materials which are obtained from industrial waste help to reduce the carbon footprint on the environment. The strength, workability, and density of these materials are increased by the usage of various activators. Smart materials operate based on external factors such as sensors, weather conditions, and so on. Smart materials are used in the Electro-Mechanical Impedance (EMI) approach to detect structural flaws in a structure. In smart homes, technology can be used to control energy consumption. Shape Memory Alloys, fiber optics, piezoelectric materials, magnetorheological fluids, and electro-rheological fluids are examples of smart materials used in smart, sustainable urbanization. The Internet of Things (IoT) developed a method for collecting construction data that reduced the structure's cost. The research will recommend appropriate techniques and materials for the Indian scenario to achieve long-term sustainable goals for the country.

Multiscale nature of electric-field-induced structural formations in non-colloidal suspensions.

Non-colloidal suspensions undergoing dipolar interactions in an electric field have been extensively studied and are also known as smart materials as they share similarities with electrorheological (ER) fluids. Although the macroscopic responses are well-documented, the multiscale nature of such suspensions is still lacking. In this study, a large-scale Stokesian dynamics simulation is used to investigate the structural formation of such suspensions in an electric field up to highly concentrated regimes across different length scales: from particle-level (microscale) to particle cluster-level (mesoscale) and stress response-level (macroscale). It is observed that at a volume fraction of ϕ ≈ 30%, the steady-state structures are the most isotropic at the microscale, but at the macroscale, their normal stress fields are the most anisotropic. Interestingly, these structures are also the most heterogeneous at both the microscale and mesoscale. Furthermore, the effects of confinement on the multiscale responses are explored, revealing that there could be a strong link between the mesoscale and macroscale. This multiscale nature can offer the potential for precisely controlling or designing ER fluids in practical applications.

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.

Enhanced response of titanium doped iron(ii) oxalate under electric field.

Electrorheological (ER) fluid, containing polarized particles within an insulating liquid, represents a smart material, the mechanical properties of which can be altered mainly by an electric field. In this work, ER fluids based on cauliflower iron(ii) oxalate doped titanium particles show excellent rheological and wetting properties by the sample co-precipitation method. The morphology of the particles is observed by SEM and the molecular structure within the particles is obtained via XRD and FTIR. The distribution of elements within the particles is obtained by EDS. Owing to a lower current density than pure iron(ii) oxalate, the SEM and optical images show an obvious chain-like structure within the ER fluids with 2 wt% and 5 wt%, respectively, under 2 kV mm-1. Then, the rheological properties of these ER fluids are tested up to 3 kV mm-1 and the results show a gratifying property of resisting shear with different shear rates (0.1-100 s-1), which is attributed to the appearance of a stable chain-like structure. At the same time, the ER efficiency and the switching performance are obtained and the static yield stress fits the relevant electric field strength well. Ultimately, an excellent sedimentation ratio is obtained from 0 h to 600 h.

Efficient and stable electrorheological fluids based on chestnut-like cobalt hydroxide coupled with surface-functionalized carbon dots.

Intrinsically polarized electrorheological fluids (ERFs) have better thermal stability than ERFs with polar molecules, so they have a broader application prospect. However, the electrorheological efficiency of the common intrinsically polarized ERF is still lower than 1500, which is related to the poor wettability between polarized materials and the continuous phase. Carbon dots (CDs) exhibit good stability, semiconductor properties and low toxicity. We prepared biomimetic chestnut-like cobalt hydroxide coupled with surface-functionalized CD particles (Co(OH)2@CDs) by a simple hydrothermal method. Then we prepared an ERF by mixing Co(OH)2@CDs with silicone oil and studied the effect of CDs on its rheology and electrorheology properties. The synergistic effect of the lipophilic groups on the surface of CDs and the biomimetic chestnut-like structure makes Co(OH)2@CDs exhibit good wettability with silicone oil, and the optimal zero-field viscosity of Co(OH)2@CDs-ERF is only 0.46 Pa s (particle mass fraction of 40%). Exceptional electrorheological efficiency (about 10 000, shear rate 0.1 s-1, 5 kV mm-1) and dynamic shear stress stability of optimal Co(OH)2@CDs-ERF can be attributed to the dielectric enhancement of the biomimetic chestnut-like structure coupled with the semiconductor properties of CDs. In addition, Co(OH)2@CDs-ERF has excellent anti-settling performance, outstanding thermal stability and low current density.

A Lightweight Flexible Semi-Cylindrical Valve for Seamless Integration in Soft Robots Based on the Giant Electrorheological Fluid

A Lightweight Flexible Semi-Cylindrical Valve for Seamless Integration in Soft Robots Based on the Giant Electrorheological Fluid

Poly(N-methylaniline)/magnetite microsphere and its electrical and magnetic dual responses

Dual electric/magnetic field-responsive magnetite coated poly(N-methylaniline)/magnetite (PNMA/Fe3O4) microspheres were synthesized via a straightforward synthetic route of chemical oxidative polymerization for monodispersed PNMA microspheres and chemical co-precipitation of Fe3O4 onto the PNMA surface. Along with their chemical and physical characterizations such as morphology, size, and crystalline structure, the electrical conductivity, magnetic properties, and dielectric properties were investigated using a low resistivity meter, vibrating sample magnetometry, and an LCR meter, respectively. All tests and analyses on the particles have proved that they have been successfully synthesized and have good magnetic saturation and dielectric properties. Studies have shown that PNMA had an appropriate conductivity so that these particles do not need for de-doping for electrorheological (ER) test. On the other hand, as a superior soft magnetic material, Fe3O4 has a good magnetic susceptibility for magnetorheological (MR) performance. The synthesized PNMA/Fe3O4 microspheres were adopted in both ER and MR fluids. The suspension made of the PNMA/Fe3O4 particles with a volume fraction of 10 vol% showed a good dual ER and MR response via a rotational rheometer. It is also found that the yield stress of ER and MR fluids followed a power-law behavior under electric/magnetic field strength with their slopes of 1.5 and 1.0, respectively. Thus, the synergistic effects of Fe3O4 and PNMA with both electrical and magnetic behaviors demonstrate their suspension possessing both ER/MR characteristics, widening their potential engineering applications.

Dynamic Response of Polyindole Coated Zinc Ferrite Particle Suspension under an Electric Field.

ZnFe2O4 particles initially synthesized through a simple solvothermal method were coated using polyindole (PIn) to prepare an actively controllable core-shell typed hybrid material under both electric and magnetic fields. An advantage of this process is not needing to add the stabilizers or surfactants commonly used for uniform coating when synthesizing core or shell-structured particles. The synthesized ZnFe2O4/PIn particles have a lower density than conventional magnetic particles and have suitable properties as electrorheological (ER) particles. The expected spherical shape of the particles was proven using both scanning electron microscopy and transmission electron microscopy. The chemical characterization was performed using Fourier-transform infrared spectroscopy and X-ray diffraction analysis. To analyze the rheological properties, a ZnFe2O4/PIn based suspension was prepared, and dynamic rheological measurements were performed for different electric field strengths using a rotary rheometer. Both dynamic and elastic yield stresses of the ER fluid had a slope of 1.5, corresponding to the conductivity model. Excellent ER effect was confirmed through rheological analysis, and the prepared ER fluid had a reversible and immediate response to repeated electric fields.

Inertial energy dissipation for weak solution of electrorheological fluids

In this paper, we study the local equation of energy for weak solution of unsteady flows of electrorheological fluids (ERFs) with shear dependent viscosities. We define a dissipation term D(u,E) which stems from an eventual lack of smoothness in the solution (u,E). Finally, we suggest calling the weak solution is dissipative when D(u,E) is nonnegative.