Isotropic Magnetorheological Elastomers Research Articles

Physical, magnetic, morphological, and optical properties of isotropic magnetorheological elastomers with cobalt as fillers for assistive sensor devices applications

Physical, magnetic, morphological, and optical properties of isotropic magnetorheological elastomers with cobalt as fillers for assistive sensor devices applications

Mechanical Properties Comparison of Isotropic vs. Anisotropic Hybrid Magnetorheological Elastomer-Fluid.

Magnetorheological (MR) materials are smart materials that can change their rheological characteristics when exposed to a magnetic field. Such rheological properties include viscosity and dynamic modulus. MR materials have emerged as one of the most efficient smart materials that can modify mechanical and viscoelastic characteristics. Depending on the medium used, MR materials can be classified into two types: magnetorheological fluids (MRFs) and magnetorheological elastomers (MREs). MREs are classified as isotropic or anisotropic based on CIP distribution inside the elastomer matrix. A unique hybrid material incorporating MRE and MRF is constructed in this work to investigate, compare, and the dynamic properties of isotropic, anisotropic, hybrid isotropic, and hybrid anisotropic MREs under various magnetic fields (0, 104, and 160.2 mT). The created samples are subjected to extensive testing, including static and dynamic evaluations. In the static tests, experiments use a compression linear displacement mode with a fixed maximum gap change of 3 mm. The temperature is maintained at a constant level of 24 °C throughout the 40 s test duration for each test, and the magnetic field is incrementally increased by varying the number of magnets, ranging from 0 to 160.2 mT for dynamic qualities using compression oscillations on a dynamic mechanical analyzer (DMA), including frequency and strain-dependent data. These experiments, carried out using sinusoidal shear movements, include an excitation frequency range of 0.1 Hz to 15 Hz while preserving, with a fixed shear strain of 2%.

Microstructure modeling and experimental verification of isotropic magnetorheological elastomers based on edge-centered cubic structure

Aiming at the problem that the existing mechanism cannot accurately predict the shear properties of magnetorheological elastomers (MREs), in this research, a physical microscopic constitutive model of isotropic MREs based on an edge-centered cubic (ECC) lattice structure was constructed to accurately reflect the shear properties of isotropic MREs under quasi-static and dynamic shear modes and different magnetic fields. In order to reduce the error of the potential energy model in the modeling process, the accuracy of the MRE total potential energy theoretical model based on the ECC lattice structure was improved by transforming to under finite strain, and the maximum improvement rate of the model accuracy was 6%. Then, in order to construct a microstructure-based dynamic model, the Langevin equation was constructed based on the ECC lattice, and an exact solvable model of the topological regular network was constructed by the Rouse chain. The relationship between the relaxation time, eigenvalue and magnetic flux density was revealed, and then the updated shear modulus was solved. Then, the modulus values of the prepared isotropic MRE samples at different frequencies and magnetic flux densities were compared with the theoretical model values, and the model failure phenomenon under dynamic high magnetic field, in which the theoretical results are inconsistent with the experimental results, was modified by the method of piecewise function and optimization parameters. The final results show that the correlation coefficient between the experimental results and the theoretical results can reach 99%.

Transient dynamics of the field induced force in the isotropic magnetorheological elastomer

The transition dynamics in silicon rubber based isotropic magnetorheological (MR) elastomers in terms of the normal force induced by an external homogeneous magnetic field is experimentally addressed. The primary goal was to evaluate dynamic performances of the MR elastic isotropic composite using a transparently presented measuring system with known characteristics in contrast to few previous studies on the topic. It was found that an increase in the magnetic field leads to an increase in the induced force and a decrease in the response time of the MR elastomer. At the same time, both the use of coarse particles as magnetic filler and a significant reduction in the stiffness of the polymer matrix reduce the response time of the MR elastomer under study. The analysis carried out takes into account the dynamics of the electromagnetic coil and the eddy currents induced in the magnet circuit. The shortest response times obtained for various MR elastomer samples are in the range of 27–72 ms for the maximal used magnetic field with an induction of 230 mT. These times correspond to the fastest previously reported ones for MR elastomers and MR elastomer based systems. In addition, the obtained results indicate the presence of different mechanisms responsible for the measured magnetodeformational effect observed in MR elastomers.

Constitutive modeling of the magnetic-dependent nonlinear dynamic behavior of isotropic magnetorheological elastomers

Isotropic magnetorheological elastomers (MREs) are smart materials fabricated by embedding magnetizable particles randomly into a polymer matrix. Under a magnetic field, its modulus changes rapidly, reversibly, and continuously, offering wide application potential in the vibration control area. Experimental observations show that there is a strong frequency, strain amplitude, and magnetic dependence of the dynamic behavior of isotropic MRE. Although important for potential applications, the magnetic-dependent nonlinear dynamic behavior of isotropic MRE has received little theoretical attention. To accurately evaluate the dynamic performance of isotropic MRE and to guide the design of isotropic MRE-based products, a new constitutive model based on continuum mechanics theory is developed to depict the magnetic-dependent nonlinear dynamic behavior of isotropic MRE. Subsequently, the numerical implementation algorithm is developed, and the prediction ability of the model is examined. The model provides a deeper understanding of the underlying mechanics of the magnetic-dependent nonlinear viscoelastic behavior of isotropic MRE. Furthermore, the model can be utilized to predict the magnetomechanical coupling behavior of isotropic MRE and therefore serves as a useful platform to promote the design and application of isotropic MRE-based devices.

Magnetic Field-Induced Deformation of Isotropic Magnetorheological Elastomers

In our research, the magnetic field-induced deformation of isotropic magnetorheological elastomer (MRE) discs loaded with two types of magnetite and an iron powder were examined. A measurement system using a microscope camera was assembled, and the magnitude of the deformation was determined from the optical contour obtained with digital image processing. We found that the MRE discs with a height-to-width aspect ratio of 1:2 underwent expansion in the direction of the external field in all cases. The magnitude of the dilatation increased with the magnetic field strength in cases of all filler materials, but the exact trend depended on the type and concentration of the filler. An inhibition of the polymerization of the matrix was observed in the case of one of the magnetite fillers, which resulted in a decreased zero-field elastic modulus at higher particle loadings. A correlation was found between the reduced elastic modulus and the increased magnitude of the deformation.

Effect of Carbonyl Iron Particle Types on the Structure and Performance of Magnetorheological Elastomers: A Frequency and Strain Dependent Study.

Magnetorheological elastomers (MREs) are smart viscoelastic materials in which their physical properties can be altered when subjected to a varying magnetic field strength. MREs consist of an elastomeric matrix mixed with magnetic particles, typically carbonyl iron particles (CIPs). The magnetic field-responsive property of MREs have led to their wide exposure in research. The potential development and commercialization of MRE-based devices requires extensive investigation to identify the essential factors that can affect their properties. For this reason, this research aims to investigate the impact of CIPs’ type, concentration and coating on the rheological and mechanical properties of MREs. Isotropic MREs are fabricated with four different CIP compositions differing between hard or soft, and coated or uncoated samples. Each MRE composition have three different concentrations, which is 5%, 10%, and 20% by volume. The dynamic properties of the fabricated samples are tested by compression oscillations on a dynamic mechanical analyzer (DMA). Frequency and strain dependent measurements are performed to obtain the storage and loss modulus under different excitation frequencies and strain amplitudes. The emphasis is on the magnetorheological (MR) effect and the Payne effect which are an intrinsic characteristics of MREs. The effect of the CIPs’ type, coating, and concentration on the MR and Payne effect of MREs are elucidated. Overall, it is observed that, the storage and loss modulus exhibit a strong dependence on both the frequency excitations and the strain amplitudes. Samples with hard and coated CIPs tend to have a higher MR effect than other samples. A decrease in the storage modulus and non-monotonous behavior of the loss modulus with increasing strain amplitude are observed, indicating the Payne effect. The results of this study can aid in the characterization of MREs and the proper selection of CIPs grades based on the application.

Giant magnetostriction in low-concentration magnetorheological elastomers

Magnetorheological elastomers (MREs) are smart composite materials that can vary their mechanical properties under the influence of an external magnetic field. In the present work, we report the giant magnetostriction of low-concentration isotropic and anisotropic MREs, by combining a soft elastomer matrix with helicoidal-shaped particles. Magnetic characterization has shown high magnetic sensitivity of the anisotropic MREs near H ≅ 0, which can be up to 400% larger comparing to the isotropic counterparts. The determination of tensile elastic modulus (E) of the MREs indicates that the anisotropic samples become softer when the magnetic field is increased from H = 0 to H = 200 Oe. Due to the higher field sensitivity of the anisotropic composites, the magneto-induced elongation contributes to the increase in the overall strain when measuring the elastic modulus at low deformation. This compliance of the MRE explains the decrease in E from H = 0 to H = 200 Oe. Magnetostriction measurements were performed and giant strain values up to 3731 ppm were obtained for isotropic samples with 3.4 vol% of Hiperco particles under a field of H = 3500 Oe. This result stands out from the literature due to the giant induced elongation, with reduced volume fraction of particles. The developments of this work are a step forward on improving smart and efficient composites, that can have many applications, such as switches, controllable valves, and vibration attenuators.

Magnetorheological behavior of isotropic silicone rubber-based magnetorheological elastomers under coupled static–dynamic compressive loads

The primary goal of this work is to test and model the magnetorheological (MR) properties of the isotropic magnetorheological elastomers (MREs) under the coupled static–dynamic compressive loads. Isotropic MREs with different contents of magnetic particles were fabricated based on the silicone elastomer. In order to apply the controllable magnetic field to the MREs and directly measure the viscoelastic force of the deformed MREs during the dynamic tests, an electromagnet with a magnetic flux density of up to 0.9 T was developed and integrated into an electric dynamic test system. The stress–strain hysteresis loops of the produced MREs were experimentally characterized under the dynamic compressive loads coupled with different static pre-strains. Effects of particle content, strain amplitude, static pre-strain and load frequency on the MR properties of the MREs were examined in terms of the characteristics of the hysteresis loops, as well as the MR effects in the storage modulus, loss modulus and pre-stress. The results revealed that irrespective of the applied magnetic field, the deformation behavior of the produced MREs was in an approximate linear viscoelastic state when the strain amplitude was less than 7.5%. Both the absolute and relative MR effects increase with the increasing particle content, and decrease with the increasing strain amplitude. Only the absolute MR effect increases with the increasing pre-strain. While varying the load frequency has almost no effect on the MR effect of the MREs. Furthermore, two empirical models were proposed respectively for predicting the storage modulus and loss modulus of the MREs as functions of the magnetic flux density, particle content, strain amplitude, pre-strain and load frequency. The graphical comparison and quantitative evaluation show that the proposed models can give effective predictions of the storage and loss moduli of the produced MREs under the applied load conditions in this work.

A novel methodology for accurate estimation of magnetic permeability of magnetorheological elastomers

Identifying a reliable nonlinear B-H curve for magneto-rheological elastomers (MREs) is a fundamental necessity for modeling and optimal design of MRE-based devices, particularly in the initial design stages. The main contribution of this study is to propose a novel methodology for the accurate estimation of magnetic permeability and nonlinear B-H curve for MREs. The proposed method involved three series of simple experiments employing an air gap electromagnet, which required only a Gauss meter to measure air gap magnetic flux density, together with formulation of an equivalent magnetic circuit (EMC). The data acquired from the first two series of experiments were used to characterize the relative magnetic permeability of MREs, while that obtained from the third series of experiments permitted an accurate estimation of the nonlinear B-H curve. For this purpose, isotropic MRE samples with 30% particle volume fraction were fabricated. Results showed that the relative magnetic permeability of MREs decreases with increasing magnetic field. The effectiveness of the proposed methodology for estimating magnetic permeability was demonstrated by comparing with that obtained from a VSM device, which revealed relatively low prediction error of 4.1%. The proposed method could thus be utilized for characterization of nonlinear magnetic permeability of MREs with minimal complexity and cost. The proposed methodology, unlike the VSM devices, could predict magnetic properties of MRE under tension/compression loadings.

Effect of lubrication on the mechanical behavior of magnetorheological elastomers in compression mode

The effect of the lubrication on the mechanical behavior of magnetorheological elastomers (MREs) in compression mode is experimentally studied. According to ISO 7743, there are two procedures to characterize specimens in compression mode. Differences in the properties of these materials between lubricated and non-lubricated conditions must be considered if devices such as vibration absorbers and isolators are to be developed. With lubrication, compression is said to be uniaxial and homogeneous, thus material properties can be obtained. Without lubrication, tests are easier to perform but results are strongly dependent on the piece shape. In this study isotropic and anisotropic MREs with iron particle volume concentrations of 10, 20, 30 and 40% are tested under different strain amplitudes, prestrain and magnetic fields for a frequency range up to 300 Hz, with and without lubrication. Important design parameters like amplitude, frequency and magnetic field dependency are showed to be dependent on lubrication.

Nanoparticle-Based Magnetorheological Elastomers with Enhanced Mechanical Deflection for Haptic Displays

Haptics allows tactile interactions between humans and digital interfaces. Magnetorheological elastomers (MREs) constitute a promising candidate material for creating the tactile interface of the future─one able to recreate 3D shapes that can be sensed with touch. Furthermore, an MRE formed by using nanoparticles, as opposed to previously used microparticles, is necessary to generate a variety of shapes involving sharp curvatures over small, micrometer-scale horizontal distances to pave the way for haptic displays with microtexture resolution. Here we fabricated both isotropic and anisotropic MREs with different concentrations (2-8 vol % nanoparticles) of soft, low-remanence ferromagnetic nanoparticles. When placed in a magnetic field gradient, isotropic MREs, nonintuitively, show higher deflection than anisotropic MREs, with the former achieving displacement on the order of a millimeter at just 100 mT. This enhanced performance in the isotropic case is explained based on the soft magnetic nature of the nanoparticles. We show that performance improves with magnetic content up to a composition of 6 vol %, where it plateaus. This behavior is attributed to the stiffness of the composite material increasing at a faster rate than the magnetization as the rigid magnetic nanoparticles are added to the elastomeric matrix. Moreover, 6 vol % microparticle-based isotropic and anisotropic MREs were fabricated and compared with the nanoparticle-based MREs. Anisotropic nanoparticle-based films show higher deflection when compared with their microparticle-based counterparts. The latter is only able to match the nanoparticle film deflection at higher applied fields of almost 300 mT. This performance difference between nanoparticle and microparticle-based films is attributed to the increased anisotropic film stiffness resulting from the larger micrometer-size particles. Finally, the optimally designed nanoparticle-based isotropic film was utilized to create a programmable and real-time reconfigurable braille-inspired interface.

Dynamic mechanical properties of magnetorheological polyurethane elastomers in comparison to existing antivibration rubbers

ABSTRACT This article primarily focused on dynamic mechanical analysis over a frequency range (0.1 to 140 Hz), temperature range (−100 to 50°C) and strain amplitude (0.1 to 5 percent). During hysteresis testing, the damping coefficient (Tanδ) and energy dissipation of isotropic and anisotropic magnetorheological elastomers with iron nanoparticles in a polyurethane rubber matrix to existing antivibration rubber were compared. Under tensile loading, energy dissipation was measured using universal testing. Different percentages of carbon black (CB) filler (30 phr, 50 phr and 70 phr) in a polyurethane matrix were selected for anti-vibration rubber comparison. During hysteresis testing, energy absorption has been found to be greater in CB Magnetorheological Elastomers(MREs) than in isotropic and anisotropic MREs, owing largely to the inclusion of CB in the formulation. CB additives were also tested on materials that were like anisotropic MREs. Relative comparative samples with the same percentage concentration of CB mixed with iron nanoparticles have greater damping characteristics and energy absorption. However, at the glass transition temperature (Tg), certain trends in energy absorption have shifted because segment flow motion of rubber chains has the greatest impact on energy absorption at glass transition temperature.

Experimental Analysis of Viscoelastic Properties of Room Temperature Vulcanized Silicone based Magnetorheological Elastomer

Magnetorheological Elastomers (MRE) endure a change in mechanical properties with the application of an externally applied magnetic field. It consists of an elastomeric matrix reinforced with ferromagnetic powdered particles. This paper focuses on the investigation of viscoelastic properties of Room Temperature Vulcanized (RTV) silicone based isotropic MRE in sandwich beam configuration by varying the volume percentage of Carbonyl Iron Powdered (CIP) reinforcement. Viscoelastic properties of the MRE core material were calculated by following the ASTM E756-05 standard. The magnetic field was applied by employing a Halbach array which was numerically analyzed using Finite Element Method Magnetics (FEMM). The magnetic field was varied up to 0.15 T. Loss factor and shear modulus were found to be strongly influenced by the percentage content of CIP. The loss factor and shear modulus of 30% MRE at 0.15 T were higher than other tested samples. The variation of natural frequency with respect to the addition of CIP was validated numerically using Modal analysis conducted in Hyperworks.

Development of New Phenomenological Models for Predicting Magnetic Permeability of Isotropic and Anisotropic Magneto-Rheological Elastomers

Designing smart devices based on magneto-rheological elastomers (MREs) is a quite challenging task due to the inherent nonlinear behavior of MREs in the presence of an applied magnetic field. In the early stage of the design process, the magnetic circuit parameters need to be optimized either via analytical approaches or FE simulations. These require a precise nonlinear magnetic permeability model (B-H curve formulation) of MREs. The model should consider the effect of essential design factors (particle volume fraction and anisotropy) and loading conditions (magnetic field and pre-strain). The main contribution of the present study is to formulate a field-dependent novel and reliable nonlinear B-H relation for MREs as functions of the basic design and loading factors. Three batches of isotropic and anisotropic MRE samples were fabricated with different particle volume fractions (15%, 30%, and 45%). Subsequently, a simple methodology was presented to determine the magnetic permeability and then the nonlinear B-H curves of the MREs considering wide variations in pre-strain (0, 12.5%, 25%, 37.5%, and 50%) as well as coil current, ranging from 0.2 A to 8 A. Experimental results showed that the relative magnetic permeability of both types of MREs increased with increasing pre-strain. Phenomenological-based models were consequently developed to estimate the nonlinear B-H curves of the isotropic and anisotropic MREs accurately and efficiently over the entire design and loading conditions considered. The proposed model can be effectively utilized for modeling and design optimization of MRE-based smart devices.

Experimental and modeling investigations on the quasi-static compression properties of isotropic silicone rubber-based magnetorheological elastomers under the magnetic fields ranging from zero to saturation field

The isotropic magnetorheological elastomers (MREs) containing three different contents of carbonyl iron particles (CIPs) based on silicone rubber were prepared, and their quasi-static compression properties under various magnetic fields were characterized by a material testing machine with specialized electromagnet. The magneto-induced actuation stress at zero strain condition as well as the deformation stress during compression process of MREs were tested. According to the magnetization model and demagnetizing energy theory, a magneto-induced actuation model of isotropic MREs was proposed. Meanwhile, a magneto-hyperelastic model was established for calculating the magnetic field- and strain-dependent deformation stress of MREs via combining the Neo–Hookean model, the magnetization model, and the magnetic dipole theory. Therefore, a new constitutive model was established to describe compression properties of isotropic MREs by considering the magneto-induced actuation and the magneto-hyperelastic behaviors. Finally, the effect of CIP content and model applicability were analyzed. It is verified that the developed compression model was able to exactly predict the compression properties of isotropic MREs with various CIP contents over the magnetic field range varying from zero field to saturation field by adopting a set of unified model parameters.

Declining Performance of Silicone-Based Magnetorheological Elastomers after Accelerated Weathering.

Magnetorheological elastomers (MRE)-based products are usually located in an area directly exposed to sunlight and rain. However, there is no specific research on the behavior of MRE after accelerated weathering. Therefore, in this study, the changes to the chemical and rheological properties of both isotropic and anisotropic MRE after accelerated weathering were examined. Treated and untreated specimens were compared. MRE specimens with 40% by weight CIP were prepared with no current excitation and another sample was prepared with 1.5 T of magnetic flux density. Each specimen was treated in an accelerated weathering machine, Q-Sun Xe-1 Xenon Test Chamber, under a UV light exposure cycle and water spray. A material characterization was carried out using FTIR and a rheometer to determine the changes to the chemical and rheological properties. The morphological analysis results showed that after the weather treatment, the surface was rough and more cavities occurred. The rheometer test results showed a significant decrease in the storage modulus of each treated MRE specimen, unlike the untreated MRE specimens. The decrease in the storage modulus value with currents of 0, 1, 2, and 3 Amperes was 66.67%, 78.9%, 85.2%, and 80.5%, respectively. Meanwhile, FTIR testing showed a change in the wave peak between the untreated and treated MRE specimens. Thermogravimetric analysis (TGA) also showed a decrease in MRE weight for each specimen. However, for both treated and untreated MRE specimens, the decrease in TGA was not significantly different. In all the tests carried out on the MRE samples, weather acceleration treatment caused significant changes. This is an important consideration for developers who choose silicone as the MRE matrix.

Effects of silica on mechanical and rheological properties of EPDM-based magnetorheological elastomers

Magnetorheological elastomers (MREs) are a kind of emerged smart material, where its responsive moduli in terms of mechanical and rheological properties are largely influenced by the presence of an external magnetic field. However, the incompatibility on the surface properties of its raw materials (fillers and matrix) may deteriorate the required properties of MREs. Therefore, in this study, the innovation of MRE by embedding silica nanoparticles as an additive has been experimentally investigated to strengthen the interactions between filler and matrix, thus resulted in enhancement of mechanical and rheological properties of MRE. The ethylene propylene diene monomer (EPDM)-based MREs were fabricated by mixing the EPDM with carbonyl iron particles (CIPs) as the main filler and different contents of silica nanoparticles (0 wt%–11 wt%) as an additive. The microstructures, magnetic properties and tensile properties of isotropic EPDM-based MREs were observed by using field emission scanning electron microscopy, vibrating sample magnetometer and Instron Universal Testing Machine, respectively. Meanwhile, the rheological properties were examined under oscillatory loadings in the absence and presence of magnetic field using rotational rheometer. The experimental results showed that the silica nanoparticles play a significant role in improving the properties of EPDM-based MREs. The adhesiveness of silica into CIPs has amended the interfacial interactions between CIPs and matrix by occupying the gaps between distributed CIPs within the MRE. Consequently, the addition of 11 wt% silica has not only improved the tensile properties (tensile strength and elongation at break), but also enhanced the MR effect compared to EPDM-based MREs without silica. Thus, incorporation of silica nanoparticles as an additive in EPDM-based MRE has the potential to be further explored and compromised to bring new innovation in real engineering applications.

Temperature-Dependent Magnetic Properties of Magnetorheological Elastomers

We report on an investigation of the temperature-dependent magnetic properties of magnetorheological elastomers (MREs). These are a class of composites that consist of magnetically permeable particles dispersed in a nonmagnetic polymeric matrix. Under the application of an external magnetic field, a large deformation occurs altering the mechanical properties of these materials. Due to their magnetoelastic coupling response, these materials are finding an increasing interest among the scientific community. These polymer-based composites’ performance depends on many factors, which temperature is one of the biggest influencing factors requiring further investigation. In this work, the magnetic properties of isotropic and anisotropic polyurethane-based MRE with different iron (Fe) particle loading fractions (50%, 60%, 70%, and 80% by weight) were investigated under different temperatures. From the analysis, the magnetization curves of these materials are observed to overlap for different measured temperature values. The variation of various magnetic properties including saturation magnetization and differential susceptibility with temperature was also determined. The results show a ~2.5% decrement in the saturation magnetization for each of the loading fractions, between the lowest (300 K) and the highest (400 K) measured temperature. On the other hand, the initial differential susceptibility exhibits different trends with increasing temperature. Generally, the magnetization response of these materials is seen to be only slightly sensitive to temperature changes. In addition, the magnetization response is observed to be highly dependent on particle loading fractions and particle orientation within the elastomer.

Modeling of Magnetic Properties of Magnetorheological Elastomers Using JA Hysteresis Model

Magnetorheological elastomers (MREs) are composite materials that consist of magnetically permeable particles in a nonmagnetic polymeric matrix. Under the influence of an external magnetic field, a reversible deformation change occurs in the mechanical properties of these materials. Due to their coupled magnetomechanical response, these materials have been found suitable for a range of applications including tunable vibration absorbers, sensors, and actuators. Notably, improvement of such devices are prerequisites to efficient energy conversion systems, hence the need to understand further the MRE technology. The Jiles-Atherton (JA) theory takes into consideration the magneto-coupling experienced by effective domains in a magnetic material. Algorithm based on the theory yields five model parameters; saturation magnetization (M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ), domain density (a), domain coupling (α), loss coefficient (k), and reversibility (c). Using JA theory, model parameters were calculated and linked to the physical attributes of Fe powder and isotropic MRE. The results show that the calculated Ms for the MRE is reasonably related to that of the Fe powder by a factor of the particle's volume fraction used in the MRE. The calculated k, a, and α provided support for the reduced pinning factor, domain density, and increased domain coupling in the MRE due to the changes in the domain structure between the two materials. From the calculated JA parameters, finite-element modeling (FEM) of the MRE hysteresis loop was performed. The analysis showed that the modeled magnetic properties including coercivity, remanence, and coordinates of the hysteresis loop tip vary with geometric position.