Folding Actuation and Locomotion of Novel Magneto-Active Elastomer (MAE) Composites

2013 ◽  
Author(s):  
Paris von Lockette ◽  
Robert Sheridan
Keyword(s):  
Magnetic Field ◽  
Barium Ferrite ◽  
Magnetic Particles ◽  
Flat Surface ◽  
Iron Particles ◽  
Soft Magnetic ◽  
Magnetorheological Elastomers ◽  
Vibration Attenuation ◽  
Magnetically Aligned ◽  
Mechanical Actuation

Magneto-active elastomers (also called magnetorheological elastomers) are most often used in vibration attenuation application due to their ability to increase in shear modulus under a magnetic field. These shear-stiffening materials are generally comprised of soft-magnetic iron particles embedded in a rubbery elastomer matrix. More recently researchers have begun fabricating MAEs using hard-magnetic particles such as barium ferrite. Under the influence of uniform magnetic fields these hard-magnetic MAEs have shown large deformation bending behaviors resulting from magnetic torques acting on the distributed particles and consequently highlight their ability for use as remotely powered actuators. Using the magnetic-torque-driven hard-magnetic MAE materials and an unfilled silicone elastomer, this work develops novel composite geometries for actuation and locomotion. MAE materials are fabricated using 30% v/v 325 mesh barium ferrite particles in Dow Corning HS II silicone elastomers. MAE materials are cured in a 2T magnetic field to create magnetically aligned (anisotropic) materials as confirmed by vibrating sample magnetometry (VSM). Gelest optical encapsulant is used as the uniflled elastomer material. Mechanical actuation tests of cantilevers in bending and of accordion folding structures highlight the ability of the material to perform work in moderate, uniform fields of μ0H = 150 mT. Computational simulations are developed for comparison. Folding structures are also investigated as a means to produce untethered locomotion across a flat surface when subjected to an alternating field similar to scratch drive actuators; geometries investigated show promising results.

Role of Magnetization Anisotropy in the Active Behavior of Magnetorheological Elastomers

2011 ◽  
Author(s):  
Paris R. von Lockette ◽  
Samuel E. Lofland
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Shear Stiffness ◽  
Shape Anisotropy ◽  
Spherical Particles ◽  
Dynamic Shear ◽  
Soft Magnetic ◽  
Magnetorheological Elastomers ◽  
Particle Level

Magnetorheological elastomers (MREs) are a re-emerging class of smart materials whose novel behavior stems from their response to magnetic fields. Historically comprised of soft-magnetic carbonyl (spherical) iron particles embedded in highly compliant matrix materials, MRE research has focused on their apparent change in shear modulus (in excess of 60%) under a magnetic field. Recent work by the authors has departed from the experimental and theoretical focus on MREs made from soft-magnetic particles (S-MREs) to investigate MREs having hard-magnetic particle inclusions (H-MREs). While H-MRE materials do not perform well in dynamic shear stiffness applications when compared to the traditional S-MREs, H-MREs provide remotely powered, fully reversible actuation capabilities that S-MREs are unable to achieve. In addition, in the same dynamic shear stiffness applications these H-MREs provide a measure of active control of which S-MREs are also incapable. This work examines the role that particle magnetization, developed due to shape anisotropy, plays in the actuation response S-MREs in contrast to H-MREs. H-MRE response is predicated on the response of the hard-magnetic particles to the external magnetic field and to neighboring particles. Since hard-magnetic particles have an internal preferred magnetic orientation, they are able to generate torques at the particle level, T = M × B, where T is the torque density, M is the magnetization, and B is the local magnetic flux density. In contrast, soft-magnetic particles may develop an induced magnetization when exposed to an external field if the particles exhibit shape anisotropy. This induced magnetization is also capable of producing torque at the particle level, however, spherical particles like those historically used in MREs are geometrically isotropic and therefore do not develop induced magnetization either and consequently the widely studied MREs comprised of soft-magnetic spherical particles generate no torque at the particle level. Shape anisotropy further complicates the mechanical response by inducing Eshelby-type shape-dependent effects on the mechanical stresses developed local to the particle. These effects vary the local particle rotation, resulting from a given macroscopic loading, and in turn affect the local magnetic field by changing the particle’s magnetization axis with respect to the external field. The result is a material system whose elastomagnetic response depends on particle shape and orientation as well as on particle magnetization. In previous works the authors used barium hexaferrite (a hard magnetic material) and carbonyl iron powders to generate MRE materials having varying particle alignment and magnetization permutations. These materials were examined in cantilever bending modes to assess and differentiate their abilities as bending actuators. In this work, finite element studies mirroring the bending tests are performed to determine the role of particle/magnetization anisotropy on the behavior. Results show strong dependence on particle shape anisotropy.

scholarly journals Influence of Additives on Thermal Properties and Morphological of Magnetorheological Elastomer

2019 ◽  
Vol 7 (4.14) ◽  
pp. 529
Author(s):  
Ku Zarina Ku Ahmad ◽  
MHA Khairi ◽  
SA Mazlan
Keyword(s):  
Natural Rubber ◽  
Smart Materials ◽  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Base Material ◽  
Rubber Matrix ◽  
Iron Particles ◽  
Soft Magnetic ◽  
Magnetorheological Elastomers ◽  
Roll Mill

Magnetorheological elastomers (MREs) are categorized as part of the smart materials class whose rheological properties can be altered under the influence of a magnetic field. MREs are fabricated by embedding soft magnetic particles such as carbonyl iron particles (CIPs) in a rubber matrix such as silicone and natural rubber. In this project, epoxidized natural rubber (ENR-50) is used as a base material with carbonyl iron particles. Sucrose Acetate Isobutyrate (SAIB) ester is added to the formulation to improve the viscosity and enhance the MRE properties. The isotropic MRE is fabricated using two roll mill and a compression mould. Various tests comprise mechanical, morphology, thermal and magnetic tests were conducted for MRE characterization purpose. The results showed that the addition of SAIB on the MRE had reduced 53% of viscosity in the rubber matrix compared to non-ester based MRE. Dispersion of magnetic particles is improved by the addition of ester as observed through Field Emission Scanning Electron Microscope (FESEM). Additionally, the thermal stability was also improved. Tensile strength of MRE consisting SAIB ester achieved maximum strength of 12.3 MPa and an elongation of 620% compared to non-ester based MRE.  

Encapsulation of Carbonyl Iron Particles with Poly(Vinyl Butyral) and their Magnetorheology

2007 ◽  
Vol 334-335 ◽  
pp. 193-196
Author(s):  
Jae Lim You ◽  
B.J. Park ◽  
I.B. Jang ◽  
Hyoung Jin Choi
Keyword(s):  
Magnetic Field ◽  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Mineral Oil ◽  
Iron Particles ◽  
Carrier Liquid ◽  
Mr Fluids ◽  
Fluid Systems ◽  
Ft Ir ◽  
Vinyl Butyral

To enhance dispersion stability of magnetorheological (MR) fluids, hybrid magnetic particles of carbonyl iron (CI)/ poly(vinyl butyral) (PVB) with core/shell microstrcutre (CI-PVB) were prepared, since pure magnetic CI based MR fluid systems show severe sedimentation of the CI particles due to the large density mismatch with the carrier liquid and difficulties in redispersion after caking. The composite particles of CI-PVB have a lower density than that of the pure CI particles, while exhibiting almost original magnetic property of the CI. Both CI and CI-PVB particles were dispersed in mineral oil (20 vol%) and their MR characteristics were examined via a rotational rheometer with a magnetic field supplier. Various characterizations of the CI-PVB particles were performed via SEM, TEM and FT-IR. Both yield stress and flow curve of shear stress as a function of shear rate of the MR fluids were investigated under applied magnetic field strengths.

MONITORING INTERPARTICLE DISTANCE IN MAGNETORHEOLOGICAL COMPOSITES

2007 ◽  
Vol 21 (28n29) ◽  
pp. 4868-4874
Author(s):  
G. BOSSIS ◽  
E. COQUELLE ◽  
C. NOEL ◽  
F. GIULIERI ◽  
A. M. CHAZE
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Energy Dissipation ◽  
Viscoelastic Properties ◽  
Magnetic Particles ◽  
Interparticle Distance ◽  
Magnetorheological Elastomer ◽  
Magnetorheological Elastomers ◽  
Magnetic Spheres ◽  
The Creation

We describe two different systems, the first one based on a magnetorheological elastomer and the second one on magnetic particles inside a liquid crystal. In both system we manage to have chain structures with particles that are not in contact. The effect of the gap between particles on the viscoelastic properties are studied. We show in particular how in magnetorheological elastomers, the energy dissipation is closely related to the creation and the motion of cavities in the gap between the particles. In liquid crystal chaining of particles can occur without applying a magnetic field. This happens if the anchoring of liquid crystal on the surface of the particles is homeotropic. We demonstrate how the combination of elastic defects and of a magnetic field allow to obtain microscopic springs made of a pair of magnetic spheres.

Sensing Behavior of Magnetorheological Elastomers

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Xiaojie Wang ◽  
Faramarz Gordaninejad ◽  
Mert Calgar ◽  
Yanming Liu ◽  
Joko Sutrisno ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Properties ◽  
Magnetic Particles ◽  
External Stimulus ◽  
Magnetorheological Elastomer ◽  
Polymer Medium ◽  
Mechanical Loads ◽  
Magnetorheological Elastomers ◽  
Impedance Response ◽  
Ferromagnetic Particles

A magnetorheological elastomer (MRE) is comprised of ferromagnetic particles aligned in a polymer medium by exposure to a magnetic field. The structures of the magnetic particles within elastomers are very sensitive to the external stimulus of either mechanical force or magnetic field, which result in multiresponse behaviors in a MRE. In this study, the sensing properties of MREs are investigated through experimentally characterizing the electrical properties of MRE materials and their interfaces with external stimulus (magnetic field or stress/strain). A phenomenological model is proposed to understand the impedance response of MREs under mechanical loads and magnetic fields. Results show that MRE samples exhibit significant changes in measured values of impedance and resistance in response to compressive deformation, as well as the applied magnetic field.

Tuning Active Magnetorheological Elastomers for Damping Applications

2010 ◽  
Vol 636-637 ◽  
pp. 766-771 ◽  
Author(s):  
Anna Boczkowska ◽  
Stefan F. Awietjan
Keyword(s):  
Magnetic Field ◽  
Carbonyl Iron ◽  
Volume Fraction ◽  
Iron Particles ◽  
Magnetorheological Elastomers ◽  
Ferromagnetic Component ◽  
Electron And Light Microscopy ◽  
Tan Δ ◽  
Microscopy Techniques ◽  
The Magnetic Field

Magnetorheological elastomers (MREs) were obtained by mixing soft polyurethane and carbonyl-iron particles. The effect of the volume fraction of the ferromagnetic particles on the MREs microstructure and properties, as well as their arrangement in relation to the external magnetic field were investigated. As a ferromagnetic component carbonyl–iron powder, with particle size from 6-9µm, was used. The amount of the carbonyl iron particles was varied from 1.5 to 33.0 %(v/v). The samples were produced with randomly dispersed and aligned carbonyl iron particles. Scanning electron and light microscopy techniques were used for the MRE microstructure observations. The rheological properties (G’, G’’ and tan δ) of the MRE were tested without and with the application of the magnetic field. It was found that the microstructure of MREs, particularly the amount and arrangement of the carbonyl-iron particles, has a significant influence on their rheological and damping properties.

"Magnetoactivated" Elastomer: An Alternative to Electroactive Polymer

2008 ◽  
Vol 144 ◽  
pp. 244-249 ◽  
Author(s):  
Yousef Razouk ◽  
Eric Duhayon ◽  
Bertrand Nogarede
Keyword(s):  
Magnetic Field ◽  
Magnetic Permeability ◽  
Applied Magnetic Field ◽  
Magnetic Particles ◽  
Young Modulus ◽  
Electroactive Polymer ◽  
Iron Particles ◽  
Silicon Matrix ◽  
Potential Applications ◽  
New Type

This paper deals with the development of a new type of composites called "magnetoactivated" polymers and the exploration of some of their potential applications. "Magnetoactivated" polymers consist of small embedding (micron-sized) magnetic particles in a high elastic silicon matrix to render it magnetically active and at the same time mechanically strong. The experimental characterizations obtained (magnetic permeability and Young modulus) were systematically compared with the values resulting from the modeling of this material.The elastic properties of our "magnetoactivated" silicon motive us to use them as pump membranes, the evolution of the displacement of the pump membrane with the applied magnetic field were verified in ANSYS and experimentally for various contents of iron particles in the silicon matrix.

Urethane Magnetorheological Elastomers - Manufacturing, Microstructure and Properties

2009 ◽  
Vol 154 ◽  
pp. 107-112 ◽  
Author(s):  
Anna Boczkowska ◽  
Stefan F. Awietjan
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Vibrating Sample Magnetometer ◽  
Iron Particles ◽  
Magnetorheological Elastomers ◽  
Microstructure And Properties ◽  
Ferromagnetic Particles ◽  
Scanning Electron

In this paper studies on urethane magnetorheological elastomers (MREs) microstructure in respect to their magnetic and mechanical properties are reported. MREs were obtained from a mixture of polyurethane gel and carbonyl-iron particles cured in a magnetic field of 100 and 300 mT. The amount of particles was varied from 1.5 to 33 vol. %. Samples with different arrangements of particles were produced. Effect of the amount of ferromagnetic particles and their arrangement on microstructure and properties in relation to the external magnetic field was investigated. The microstructure was studied using scanning electron microscopy. Magnetic properties were measured using vibrating sample magnetometer. Rheological and mechanical properties under compression were also examined.

scholarly journals Gelatine-Coated Carbonyl Iron Particles and Their Utilization in Magnetorheological Suspensions

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2503
Author(s):  
Tomas Plachy ◽  
Patrik Rohrer ◽  
Pavlina Holcapkova
Keyword(s):  
Magnetic Field ◽  
Liquid Medium ◽  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Silicone Oil ◽  
Rheological Parameters ◽  
Iron Particles ◽  
Magnetorheological Suspensions ◽  
Magnetorheological Suspension ◽  
Dynamic Yield

This study demonstrates the formation of biocompatible magnetic particles into organized structures upon the application of an external magnetic field. The capability to create the structures was examined in silicone-oil suspensions and in a gelatine solution, which is commonly used as a blood plasma expander. Firstly, the carbonyl iron particles were successfully coated with gelatine, mixed with a liquid medium in order to form a magnetorheological suspension, and subsequently the possibility of controlling their rheological parameters via a magnetic field was observed using a rotational rheometer with an external magnetic cell. Scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis confirmed the successful coating process. The prepared magnetorheological suspensions exhibited a transition from pseudoplastic to Bingham behavior, which confirms their capability to create chain-like structures upon application of a magnetic field, which thus prevents the liquid medium from flowing. The observed dynamic yield stresses were calculated using Robertson–Stiff model, which fit the flow curves of the prepared magnetorheological suspensions well.

Characterization of actuation properties of magnetorheological elastomers with embedded hard magnetic particles

2012 ◽  
Vol 23 (9) ◽  
pp. 1049-1054 ◽  
Author(s):  
Jeong-Hoi Koo ◽  
Alexander Dawson ◽  
Hyung-Jo Jung
Keyword(s):  
Magnetic Materials ◽  
Magnetic Particles ◽  
Iron Particles ◽  
Magnetorheological Elastomer ◽  
Hard Magnetic Materials ◽  
Magnetorheological Elastomers ◽  
Cantilevered Beam ◽  
Magnetic Poles ◽  
New Generation

This study investigates a new generation of magnetorheological elastomers based on hard magnetic particles. Unlike traditional magnetorheological elastomers that use iron particles, a dispersion of hard magnetic materials aligned in an electromagnetic field will produce a magnetorheological elastomer with magnetic poles. When a magnetic field is applied, perpendicularly to these poles, the filler particles generate torque and cause rotational motion of the magnetorheological elastomer blend. The primary goal of this study is to fabricate and characterize the actuation properties of magnetorheological elastomers filled with various hard magnetic particles. To this end, samples of magnetorheological elastomers consisting of hard magnetic materials were fabricated using four different particle types, and a test setup (electromagnet) was constructed. After mounting the magnetically anisotropic samples in a fixed-free configuration, uniform magnetic fields are applied to the samples (perpendicular to the poled direction), which causes the sample to bend, similar to a cantilevered beam. The blocked force and tip displacement of the samples were measured to characterize actuation properties of the samples. The results show that the responses of the deflection and the blocked force at the tip show linear trends over a reasonable range, suggesting that magnetorheological elastomers consisting of hard magnetic materials can be used as bending-type actuators in small mechanical systems and devices.

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