Properties Of Magnetorheological Elastomers Research Articles

Experimental and theoretical investigation on magnetorheological elastomers containing carbonyl iron particles coated with silane coupling agent

Magnetorheological (MR) elastomer composites, comprising soft silicone rubber, various additives, and different weight fractions of carbonyl iron particles (CIPs) coated with silane coupling agent, are produced via a novel manufacturing process in an anisotropic state. This study encompasses both experimental and modeling investigations into the dynamic viscoelastic properties of magnetorheological elastomer (MREs) in shear mode under varying magnetic fields, displacement amplitudes, and frequencies. Two MRE vibration mitigation devices are fabricated to experimentally assess the shear storage modulus and the loss factor of MREs. The experimental findings reveal a pronounced MR effect in the MRE devices, where both the shear storage modulus and the loss factor increase with rising magnetic fields, frequencies, and particle weight fractions, yet decrease with higher displacement amplitudes. A modified fractional-derivative equivalent parametric model, grounded in a magnetic field- and frequency-dependent shear modulus model along with internal variable theory, is proposed to describe the effects of these key influencing factors on the MREs’ dynamic viscoelastic properties. Comparative analysis of experimental and numerical data demonstrates that this refined mathematical model can accurately represent the dynamic viscoelastic properties of MREs.

A physics-guided deep learning model for predicting the magneto-induced mechanical properties of magnetorheological elastomer: Small experimental data-driven

Magnetorheological elastomer (MRE) is a novel intelligent material, which shows excellent potential in vibration control applications. Previous researches have fully demonstrated that the magneto-induced shear storage modulus of MRE largely determines the vibration control effect. However, both existing theoretical and experimental ways to measure the magneto-induced shear storage modulus of MRE face their own shortage. Therefore, a novel physics-guided deep learning model is proposed to efficient predict the magneto-induced mechanical properties of MRE based on Magnetic Dipole theory and data-driven methods. A small database is built by collecting the magneto-induced shear storage modulus of MRE with different material ratios tested on a special shear rheometer. The proposed model trained with small training samples and its prediction results fit well with experimental values (average R2 of 0.99) which is superior to existing constitutive models. The training only takes 25 s, which significantly shortens the time compared to the experiment. Furthermore, the proposed model effectively predicts the magneto-induced storage modulus of MRE and has good generalization and superior transfer performance.

Properties and influence of magnetic fields on iron particles of anisotropic magnetorheological elastomers

The magnetorheological elastomer (MRE) is an intelligent material whose mechanical properties can be rapidly adjusted under a magnetic flux density. This material’s mechanical properties change due to the interaction between the iron particles inside the material. Understanding the influence of magnetic flux on iron particles in MRE materials is essential. Studies have proven that the distance and angle of inclination between iron particles significantly affect the magnetic flux density and the interaction force between the particles. Therefore, the distribution of iron particles substantially affects the material’s properties. However, understanding magnetic flux through magnetic particles is necessary to improve the material’s mechanical properties and to design magnetic field systems in systems using the materials. This study maps three problems affecting magnetic flux density to the properties of MRE. First, the mechanical characteristics of the MRE were presented in the frequency, amplitude, magnetic flux density, and magnetic flux inclination domains relative to the particle chain. Next, the influence of the magnetic flux on the particle chain was investigated based on the dipole interaction model and the magnetic force on iron particles. The finite element method also explored the magnetic flux distribution in the MRE material. Finally, the response of the single-degree-of-freedom damping system is tested experimentally. The results show that the influence of the magnetic flux on the iron particles in the MRE material is significant. The research results aim to improve the mechanical properties of MRE materials.

Development of a Novel Magneto-Rheological Elastomer-Based Semi-Active Seat Suspension System

Human operators in the transportation sector are exposed to whole-body vibration (WBV) while driving. Occupational exposure to WBV, predominant at low frequencies (<20 Hz), has been linked to spinal injuries and reduced functioning. This study aims at the design development of a novel semi-active seat suspension system featuring magneto-rheological elastomers (MREs) to mitigate the WBV. The proposed suspension system allows a greater range of strokes, while ensuring the MRE remains within an acceptable level of deformation. Several MRE samples were fabricated and characterized under shear mode. Afterward, a field- and frequency-dependent phenomenological model was developed to predict the viscoelastic properties of MREs as functions of both the excitation frequency and applied magnetic field. The MRE material model was subsequently used to design and optimize an adaptive seat suspension system incorporating a C-shaped MRE-based isolator in parallel and series with passive springs. The proposed adaptive seat suspension system demonstrated a frequency shift of 29% by increasing the applied current from 0 to 2 A. Finally, a 6-DOF lumped parameter model of a seated human subject combined with the proposed semi-active suspension system featuring the MRE isolator has been formulated to investigate the vibration transmissibility from the floor to the subject’s head.

Particle-reinforced elastomer model to analyse viscoelastic properties of flake-shaped electrolyte iron particle-based magnetorheological elastomer

This paper uses parallel-plate-plate rheometry to focus on the magnetic field-dependent nonlinear viscoelastic behaviour of flake-shaped electrolyte iron powder-based magnetorheological elastomer (MRE). MRE was prepared using liquid silicon rubber as a base, a curing agent and electrolyte iron particles as fillers. Three MRE samples having 60%, 40%, and 0% filler weight fractions were prepared. The curing was carried out at 300 K. The thickness of the sample was 1.00 ± 0.04 mm. Scanning electron microscopy results showed uniform dispersal of particles within a matrix. The swelling measurement technique was used to confirm the enhanced reinforced properties of elastomer by calculating the cross-link density. The magnetic volume fraction evaluated from magnetisation measurements yields values of 18.7% for MRE-60 and 8.7% for MRE-40. Both moduli’s field-induced linear and nonlinear amplitude dependence were analysed using the modified particle-reinforced elastomer model. The result indicates that filler particles adsorbed on polymer chains were essential in determining the reinforcing properties of MRE. The improved cross-link density and particle morphology were responsible for the enhanced field-induced magnetorheological effect (277%). This value is nearly three times greater than that observed in spherical particles-based MRE.

Properties of inhomogeneous-type magnetorheological elastomer formed in the presence of a magnetic field with tilted angles

Magnetorheological elastomers (MRE) are smart materials whose mechanical properties can be tuned using an applied magnetic field. Many studies have shown that MRE properties are influenced by particle size, particle volume fraction, and matrix material type. The particle-magnetic dipole theory has demonstrated that the angle of the particle chains significantly affects the properties. This study investigated the effects of the alignment angle of the particle chains on the properties of MREs. The inclination angle is a parameter associated with the external magnetic flux density. MRE samples fabricated under a magnetic field with different tilt angles were prepared for the shear tests. The primary properties of MRE, such as viscoelasticity, magnetic-induced properties, and hysteresis, were comprehensively investigated in the samples. The equivalent stiffness and loss of energy changed significantly in the tilted angle domain. The force–displacement loops also showed a clear difference among the samples when the experiments were performed at the same amplitude, frequency, and magnetic flux density. The experimental results show that the magnetic and hysteretic properties strongly depend on the initial tilt angle of the chain.

THE EFFECTS OF ADDITIVE ON THE IMPACT ABSORPTION CAPABILITY OF MAGNETORHEOLOGICAL ELASTOMER

Magnetorheological elastomer (MRE) is a smart material whose its damping and stiffness characteristics change when exposed to a magnetic field. MRE usually contains rubber and ferrous particles. Other materials such as additives, can improve physical properties of MRE during cyclic loading. However, limited research has been conducted into the effect of incorporating these additives on MRE performance when subjected to impact loading. Additives can change the MRE’s structure such as stiffness and enhance its damping properties, especially its impact absorption capabilities. This study focuses on the force-displacement characteristics of additives and their relationships with MRE containing additives in impact absorption applications. This study uses ferrite, zinc, aluminum, and copper as additives in MREs fabrication and subjects the MREs to a drop impact test at varying applied currents of 0, 0.5, 1.0, 1.5, and 2.0 ampere. The experimental results show that the MRE containing ferrite has the highest average impact absorption capability of 2.24 Nm, followed by zinc, aluminum, and copper.

Magneto-mechanical properties of anisotropic magnetorheological elastomers with tilt angle of magnetic chain under compression mode

Characterization of mechanical properties of magnetorheological elastomers (MREs) is essential for the design of smart materials and devices with customized features and functionalities. While the properties of MREs under shear mode have been extensively researched, MREs with tilt angle under compression mode have been less exploited. In this study, a magneto-mechanical model of anisotropic MREs is established based on magnetic dipole theory and energy method considering the reconfiguration effect of compressive strain on the microstructure of the magnetic chain. This leads to the provision of a dynamic magneto-mechanical model of the anisotropic MREs, incorporating the magneto-induced mechanical model, by using the robust fitting method. Experiments were conducted to assess the force–deflection (stress–strain) characteristics of MREs with tilt angle under compression mode, subject to the regulation of the tilt angle of magnetic chain, magnetic flux density, and mass fraction of magnetic particles. The magnetic-induced modulus, obtained from the theoretical model, is experimentally verified through magneto-mechanical testing, alongside an analysis on the dynamic mechanical properties under different dynamic strain amplitudes and frequencies. The mean square error (MSE) in terms of magneto-mechanical storage modulus in the robust fitting ranges from 2.73% to 10.86%. Experimental results also show that the range of magneto-induced stress (typically from 178 KPa to 74.6 KPa) decrease when the tilt angle of the magnetic chain increases (from 15° to 25°) corresponding to 60% mass fraction. The compression strain of the anisotropic MREs, affecting both the spacing of adjacent magnetic particles and the tilt angle of magnetic chain, causes significant changes in the magnetic-induced modulus. In addition, the hysteresis loops under different deformation (Mullins effect) show an increasing energy dissipation with decreasing tilt angle.

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.

Influence of Gamma Radiation on the Damping Property of Magnetorheological Elastomer.

Magnetorheological elastomer (MRE) is a kind of smart material, whose mechanical property can be controlled by the external magnetic field quickly and reversibly. The damping property of MRE is one of the most concerned properties when designing MRE based devices. In this work, the influence of gamma radiation on the damping property of MRE was investigated. Six different exposures of gamma radiation were applied to the MRE samples. The highest gamma radiation dose was up to 1 × 105 Gy(Si), which can cover most of the engineering application scenarios. The influence of gamma radiation on the damping-strain relation and the damping-magnetic-field relation were studied. The probable mechanisms were discussed in detail. It is found that the gamma radiation does not affect the variation trend of loss factor of MRE with increasing strain amplitude or magnetic flux density. But it affects the variation trend of the maximum change of strain-induced or magnetic-field-induced loss factor of MRE. Besides, with constant strain and constant magnetic flux density, the loss factor of MRE shows w-shape variation trend with increasing gamma radiation dose. It is considered to be resulted from the combined action of the intrinsic damping and the interfacial friction damping of MRE.

Natural Weathering Effects on the Mechanical, Rheological, and Morphological Properties of Magnetorheological Elastomer (MRE) in Tropical Climate.

Magnetorheological elastomer (MRE) materials have the potential to be used in a wide range of applications that require long-term service in hostile environments. These widespread applications will result in the emergence of MRE-specific durability issues, where durability refers to performance under in-service environmental conditions. In response, the outdoor tropical climatic environment, combined with the effects of weathering, will be the primary focus of this paper, specifically the photodegradation of the MRE. In this study, MRE made of silicone rubber (SR) and 70 wt% micron-sized carbonyl iron particles (CIP) were prepared and subjected to mechanical and rheological testing to evaluate the effects under natural weathering. Magnetorheological elastomer samples were exposed to the natural weathering conditions of a tropical climate in Kuala Lumpur, Malaysia, for 30 days. To obtain a comprehensive view of MRE degradation during natural weathering, mechanical testing, rheology, and morphological evaluation were all performed. The mechanical and rheological properties test results revealed that after 30 days of exposure and known meteorological parameters, Young’s modulus and storage modulus increased, while elongation at break decreased. The degradation processes of MRE during weathering, which are responsible for their undesirable change, were given special attention. With the help of morphological evidence, the relationship between these phenomena and the viscoelastic properties of MRE was comprehensively defined and discussed.

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.

Multiscale numerical modeling of magneto-hyperelasticity of magnetorheological elastomeric composites

Mechanical properties of magnetorheological elastomers (MREs) are essential for their engineering applications. While the magneto-elastic responses of MREs under large deformation are obtained with experimental methods, microstructure-based modeling and simulation can indicate the physical mechanisms that further provide guidelines for engineering design. We herein propose a computational micromechanics-based multiphysics coupling model to reveal the overall magneto-hyperelastic properties of MREs. Interactions among ferromagnetic particles in MREs are defined in terms of magnetic body forces. The coupled magnetic and mechanical fields are solved in the three-dimensional representative volume elements with chained microstructures under large deformation. The macroscopic stresses are obtained by the computational homogenization procedures with consideration of the microscopically coupled fields of stresses and magnetic body forces. Effects of demagnetizing field and microstructures on the overall magnetic stresses are particularly emphasized. The mechanical properties obtained from several groups of experiments are quantitatively predicted and interpreted which further verifies the applicability and correctness of the proposed method.

Temperature Dependent on Mechanical and Rheological Properties of EPDM-Based Magnetorheological Elastomers Using Silica Nanoparticles.

Temperature is one of the most influential factors affecting the performance of elastomer matrix in magnetorheological elastomer (MRE). Previous studies have utilized silica as a reinforcing filler in polymer composite and as a coating material in MRE to improve the thermal stability of the base material. However, the usage of silica as an additive in the thermal stability of MRE has not been explored. Thus, in this study, the effect of silica as an additive on the temperature-dependent mechanical and rheological properties of ethylene propylene diene monomer (EPDM)-based MREs was investigated by using 30 wt.% carbonyl iron particles (CIPs) as the main filler, with different contents of silica nanoparticles (0 to 11 wt.%). The microstructure analysis was examined by using field-emission scanning electron microscopy (FESEM), while the thermal characterizations were studied by using a thermogravimetric analyzer and differential scanning calorimetry. The tensile properties were conducted by using Instron Universal Testing Machine in the absence of magnetic field at various temperatures. Meanwhile, the rheological properties were analyzed under oscillatory loadings in the influence of magnetic field, using a rotational rheometer at 25 to 65 °C. The results revealed that the temperature has diminished the interfacial interactions between filler and matrix, thus affecting the properties of MRE, where the tensile properties and MR effect decrease with increasing temperature. However, the presence of silica capable improved the thermal stability of EPDM-based MRE by enhancing the interactions between filler and matrix, thus reducing the interfacial defects when under the influence of temperature. Consequently, the incorporation of silica nanoparticles as an additive in EPDM-based MRE requires more exploration, since it has the potential to sustain the properties of MRE devices in a variety of temperature conditions. Thus, the study on the temperature-dependent mechanical and rheological properties of MRE is necessary, particularly regarding its practical applications.

Field-Dependent Rheological Properties of Magnetorheological Elastomer with Fountain-Like Particle Chain Alignment.

Magnetorheological elastomer (MRE) consists of magnetic particles known as carbonyl iron (CIPs), which have been locked in a silicone-based matrix, in various alignments. However, current MRE exhibits inadequate rheological properties due to several issues such as particle alignments. Therefore, in this study, a new approach of the particle alignment of CIPs in MRE, namely fountain-like structure, is introduced. It is expected that this kind of MRE exhibits enhancement rheological responses, in off- and on-state conditions. This work includes the development of a new mold that can produce various directions of magnetic flux lines in order to have fountain-like structures of CIPs in MRE, during the curing process. Three types of particle alignments in MRE, namely isotropic, fountain-like and inverted fountain-like, are fabricated. The rheological properties of MRE in terms of storage modulus and MR effect are measured in an oscillatory shear mode using a rheometer. The results have revealed that fountain-like MRE exhibits higher storage modulus than the isotropic MRE, approximately 0.6 MPa of increment in the strain sweep test, in an on-state condition. Furthermore, it has been demonstrated from strain, frequency and the current sweep test that the rheological properties of fountain-like MRE related to storage modulus and magnetorheological (MR) effect are higher compared to the inverted fountain-like MRE.

Influence of chain-like cobalt particles on the properties of magnetorheological elastomers

The different pre-structure formed by the particles determine the performance of magnetorheological elastomers (MREs). In this study, spherical cobalt particles with a diameter of 2–5 μm and chain-like cobalt particles (CCPs) composed of spherical particles with a diameter of about 1 μm with a chain length of 10–40 μm were respectively prepared. These two kinds of particles were used to prepared MREs under different orientation magnetic fields. The effects of different chain-like microstructures on the performance of MRE are compared. The dynamic viscoelastic test results of MREs show that the chain-like particles increased the movement resistance in the matrix, thereby increasing the damping factor of CCP-MREs. The special chain-like particles improved the Payne effect factor and magnetic field-induced storage modulus of isotropic CCP-MRE. It is worth noting that the performance of anisotropic CCP-MRE is different from traditionally believed performance improvement. Based on this work, a relationship curve between the MR effect and the adjacent particles’ distance was proposed.

A macroscopic viscoelastic model of magnetorheological elastomer with different initial particle chain orientation angles based on fractional viscoelasticity

In this paper, a macroscopic viscoelastic modeling method for magnetorheological elastomer (MRE) based on fractional derivative model is presented to describe the dynamic viscoelastic properties of MRE with different initial particle chain orientation angles. The angle between the particle chain and the applied magnetic field is used as an indicator to describe the directionality of the particle chain. MRE samples with different initial inclination angles have been designed and fabricated. The dynamic viscoelastic properties of different MRE samples under shear working mode were measured using a parallel plate rheometer. The dynamic viscoelastic properties of MRE with different initial inclination angles are analyzed under the test conditions of different strain amplitude, frequency and magnetic flux density. The test results show that the initial inclination angle of the particle chain in the MRE has a significant effect on the dynamic viscoelastic properties of the MRE. A polynomial function is used to describe the relationship between the initial particle chain orientation angle and the magneto-induced modulus of MRE. A phenomenological model of magneto-induced modulus is established based on the fractional derivative model. The model parameters are identified using the nonlinear least square method. The predicted values of the model are in good agreement with the experimental results, indicating that the model can well describe the dynamic viscoelastic properties of MRE.

A novel chain-cluster model of magnetorheological elastomer for the dynamic mechanical performance research

The existing research on magnetorheological elastomer (MRE) mainly focused on the improvement of MRE formula and structural design of MRE devices. As to the microscopic mechanism, less research has been done. Based on the scanning electron micrograph of MRE, a novel chain-cluster model of MRE was constructed in this study. Particle size and particle distance were introduced simultaneously to the constitutive relation of MRE. The dynamic mechanical properties of MRE are studied theoretically and experimentally. Using the constructed chain-cluster model of MRE, the effect of magnetic field, particle volume fraction and strain on the magnetic-induced modulus of MRE were simulated. Rotating rheometer was adopted to test the magnetic response characteristics of MREs. Simulation and test results showed that the maximum magnetic-induced modulus tested experimentally was in good agreement with that calculated theoretically. Thus, the constructed chain-cluster model of MRE shows an important role in the field of intelligent vibration. It not only makes great sense in the prediction of MRE property but provides guidance on the property improvement of MRE.

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.

Micromechanics-based simulation of anisotropic magneto-mechanical properties of magnetorheological elastomers with chained microstructures

Magnetorheological elastomers (MREs) are ferromagnetic particle-reinforced composites that have a wide application prospect in engineering because of their tunable stiffness with applied magnetic fields. While a large number of experimental efforts have been carried out to characterize the magneto-mechanical properties of MREs, few physics-based quantitative modeling and simulation have been explored. Here a micromechanics-based finite element model and computational homogenization is developed to determine the field-dependent shear moduli of MREs. The magneto-elastic coupling is realized with the magnetic field-induced body forces in the local mechanical field. The three-dimensional body forces are solved with consideration of magnetization and demagnetizing fields. Effects of essential microstructure parameters (particle concentration and particle spacing) are investigated on the effective magneto-mechanical properties of chain-structured MREs. The numerical results demonstrate that the microstructures and demagnetizing field have significant effects on the field-induced moduli of MREs. RVEs with appropriate microstructures are selected to compare our model predictions of magneto-mechanical properties with multiple groups of experiment data in the literature, showing the capability and validity of the proposed model.