Fabrication Of Magnetorheological Elastomers Research Articles

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.

The fabrication and properties of magnetorheological elastomers employing bio-inspired dopamine modified carbonyl iron particles

To obtain magnetorheological elastomers (MREs) with improved mechanical properties and exhibiting an enhanced magnetorheological (MR) effect, bio-inspired dopamine modification has been used to improve the functionality at the surface of carbonyl iron (CI) particles. Various techniques including x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to confirm that a polydopamine (PDA) layer of about 27.5 nm had been successfully deposited on the surface of the carbonyl iron particles prior to their inclusion in the MRE composites. The magnetic properties of PDA modified CI particles were shown to be almost the same as those for untreated CI particles. With the introduction of a PDA layer to the surfaces of the particles, both the tensile strength and the elongation at break of the MREs were improved. Furthermore, the MRE composites filled with PDA-coated CI particles exhibited lower zero-field storage moduli but higher magnetic field induced storage moduli when magnetization saturation was reached. The absolute and relative MR effect for the MREs reached 0.68 ± 0.002 MPa and 294% respectively, which were higher than those of MREs with pristine CI particles whose absolute and relative MR effect were 0.57 ± 0.02 MPa and 187% respectively. The findings of this work provide insights into enhanced fabrication of MREs with both improved mechanical properties and magneto-induced performance.

Tunable low range Gr induced magnetorheological elastomer with magnetically conductive feedback

The effect of graphite (Gr) based magnetorheological elastomer (MRE) on resistance is experimentally evaluated in this research. Isotropic and anisotropic MRE samples are prepared by utilizing Gr as a filler in MRE fabrication. The physical, rheological and resistance properties of Gr-MRE are investigated and compared to those of typical or conventional MREs without Gr. Morphological aspects of Gr-MRE are characterized by field emission scanning electron microscope (FESEM), scanning electron microscope and energy dispersive x-ray spectroscopy, while rheological properties are evaluated using a rheometer. Subsequently, the resistance properties are investigated by using the designated test-rig. Based on the resistance evaluation, a curve describing the relationship of resistance (R) under different applied forces (F) and different magnetic fields (B) are established and plotted. Moreover, it is observed that the FESEM images shows the presence of Gr fractions, which contributes to the conductivity property of MRE. It is also observed that with the addition of Gr, the rheological and conductivity properties such as the storage modulus and resistance response are improved parallel with the increment of magnetic field. It is also demonstrated that the addition of Gr in MRE can contribute to the use of force detection in sensing devices.

Rheological and Resistance Properties of Magnetorheological Elastomer with Cobalt for Sensor Application

Cobalt particles have been introduced as a filler due to the advantages of embedding their magnetic and electrical properties in magnetorheological elastomer (MRE). In the present research, the rheology and resistance of MRE are experimentally evaluated. Isotropic and anisotropic MRE samples containing silicone rubber and cobalt particles were fabricated. The magnetic properties of MRE are conducted using a vibrating sample magnetometer (VSM). The morphological aspects of MRE are observed by using field emission scanning electron microscopy (FESEM) and characterized by energy-dispersive X-ray spectroscopy (EDX). Rheological properties under various magnetic field strengths were measured for the magnetic field, strain amplitude, and frequency sweep test by using a parallel-plate rheometer. Subsequently, the resistance of MRE is tested under different applied forces and magnetic fields. The MRE storage modulus depicted an enhancement in field-dependent modulus across all the applied magnetic fields. The electrical resistance generated from the sample can be manipulated by external magnetic fields and mechanical loads. The conductivity of MRE is due to the existence of cobalt arrangements observed by FESEM. By introducing cobalt as filler and obtaining satisfactory results, the study might open new avenues for cobalt to be used as filler in MRE fabrication for future sensing applications.

Enhancement of Particle Alignment Using Silicone Oil Plasticizer and Its Effects on the Field-Dependent Properties of Magnetorheological Elastomers.

The existing mold concept of fabricating magnetorheological elastomer (MRE) tends to encounter several flux issues due to magnetic flux losses inside the chamber. Therefore, this paper presents a new approach for enhancing particle alignment through MRE fabrication as a means to provide better rheological properties. A closed-loop mold, which is essentially a fully guided magnetic field inside the chamber, was designed in order to strengthen the magnetic flux during the curing process with the help of silicone oil (SO) plasticizers. The oil serves the purpose of softening the matrix. Scanning electron microscopy (SEM) was used to observe the surface morphology of the fabricated MRE samples. The field-dependent dynamic properties of the MREs were measured several ways using a rheometer, namely, strain sweep, frequency sweep, and magnetic field sweep. The analysis implied that the effectiveness of the MRE was associated with the use of the SO, and the closed-loop mold helped enhance the absolute modulus up to 0.8 MPa. The relative magnetorheological (MR) effects exhibited high values up to 646%. The high modulus properties offered by the MRE with SO are believed to be potentially useful in industry applications, particularly as vibration absorbers, which require a high range of stiffness.

Material Characterizations of Gr-Based Magnetorheological Elastomer for Possible Sensor Applications: Rheological and Resistivity Properties.

Considering persistent years, many researchers continuously seek an optimum way to utilize the idea of magnetorheology (MR) materials to be practically used for everyday life, particularly concerning resistivity sensing application. The rheology and resistivity of a graphite (Gr)-based magnetorheological elastomer (Gr-MRE) were experimentally evaluated in the present research. Magnetorheological elastomer (MRE) samples were prepared by adding Gr as a new additive during MRE fabrication. The effect of additional Gr on the rheological and resistivity properties were investigated and compared with those of typical MREs without a Gr additive. Morphological aspects of Gr-MRE were characterized using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX). Rheological properties under different magnetic fields were evaluated using a parallel-plate rheometer. Subsequently, the resistivity of all samples was measured under different applied forces and magnetic fields. From the resistivity evaluation, two relationship curves resistance (R) under different applied forces (F) and different magnetic fields (B) were established and plotted by using an empirical model. It was observed from the FESEM images that the presence of Gr fractions arrangement contributes to the conductivity of MRE. It was also observed that, with the addition of Gr, rheological properties such as the field-dependent modulus can be improved, particularly at low strain amplitudes. It is also demonstrated that the addition of Gr in MRE can contribute to the likely use of force detection in tactile sensing devices.

Optimization of pre-structuring parameters in fabrication of magnetorheological elastomer

Pre-structuring of magnetic particles during fabrication of magnetorheological elastomer (MRE) is a crucial step, which results in the formation of chain-like columnar structures in the rubber matrix. In this study, MRE based on natural rubber and carbonyl iron particles were prepared. The Taguchi method was utilized to study the effect of several dominating factors during the fabrication process such as pre-curing time, pre-curing temperature and applied magnetic field during curing on the loss tangent (tan δ) and tensile properties. Tan δ was measured through parallel-plate rheometer over a frequency range of 1–100Hz and a strain amplitude range of 0.1–6%. Tensile properties were measured with a universal tensile testing machine. The obtained data were statistically analyzed using S/N ratios and ANOVA in order to predict the optimal combination of factors, and then further experiments were conducted for verification purpose. Results indicated that the magnetic field had the greatest influence on tan δ when measured over a range of frequency and elongation at break. Furthermore, pre-curing time and magnetic field were found to influence tan δ when measured over a range of strain amplitude. However, none of the factors exhibited significant influence on tensile strength. In addition, the morphology of MRE was examined using scanning electron microscopy (SEM).

Design of magnetic Circuit Simulation for Curing Device of Anisotropic MRE

The strength of magnetic field during fabrication of magnetorheological elastomer (MRE) plays a crucial role in order to form a pre-structured MRE. So far, gaussmeter were used to determine the magnetic intensity subjected to the MRE during curing. However, the magnetic flux reading through that measurement considered less accurate. Therefore, a simulation should be done to figure out the magnetic flux concentration around the sample. This paper investigates the simulation of magnetic field distribution in a curing device used during curing stage of anisotropic magnetorheological elastomer (MRE). The target in designing the magnetic circuit is to ensure a sufficient and uniform magnetic field to all the MRE surfaces during the curing process. The magnetic circuit design for the curing device was performed using Finite Element Method Magnetic (FEMM) to examine the magnetic flux density distribution in the device. The material selection was first done instantaneously during a magnetic simulation process. Then, the experimental validation of simulation was performed by measuring and comparing the actual flux generated within the specimen type and the one from the FEMM simulation. İt apparent that the data from FEMM simulation shows an agreement with the actual measurement. Furthermore, the FEMM results showed that the magnetic design is able to provide sufficient and uniform magnetic field all over the surfaces of the MRE.

Formation of core–shell structured complex microparticles during fabrication of magnetorheological elastomers and their magnetorheological behavior

To improve mechanical and magnetorheological properties of magnetorheological elastomers (MREs), a facile method was used to fabricate high-performance MREs which consisted of the core–shell complex microparticles with an organic-inorganic network structure dispersed in an ethylene propylene diene rubber. In this work, the proposed magnetic complex microparticles were in situ formed during MREs fabrication as a result of strong interaction between matrix and CIPs using carbon black as a connecting point. The morphology of both isotropic (i-MREs) and anisotropic MREs (a-MREs) was observed by scanning electron microscope (SEM). The effects of carbonyl iron particle (CIP) volume content on mechanical properties and hysteresis loss of MREs were investigated. The effects of CIP volume content on the shear storage modulus, MR effect and loss tangent were studied using a modified dynamic mechanical analyzer under applied magnetic field strengths. The results showed that the orientation effect became more pronounced with increasing CIPs in the a-MREs, whereas CIPs distributed uniformly in the i-MREs. The tensile strength, tear strength and elongation at break decreased with increasing CIP content up to 40 vol.%, while the hardness increased. It is worth noting that the tensile strength of i-MREs and a-MREs containing 40 vol.% CIPs still had high mechanical properties as a result of good compatibility between complex microparticles and rubber matrix. The MR performance of shear storage modulus and damping properties of MREs increased remarkably with CIP content due to strong dipole–dipole interaction of complex microparticles. Besides, the hysteresis loss increased with increasing CIP content as a result of magnetic field induced interfacial sliding between complex microparticles.