VISCOELASTIC PROPERTIES OF SILICONE-BASED MAGNETORHEOLOGICAL ELASTOMERS

2007 ◽  
Vol 21 (28n29) ◽  
pp. 4790-4797 ◽  
Author(s):  
HOLGER BÖSE
Keyword(s):  
Magnetic Field ◽  
Smart Materials ◽  
Viscoelastic Properties ◽  
Magnetic Particles ◽  
Relative Increase ◽  
Matrix Composites ◽  
Mechanical Stiffness ◽  
Storage And Loss Moduli ◽  
Order Of Magnitude ◽  
Reported Data

Magnetorheological (MR) elastomers are composite materials consisting of magnetic particles in elastomer matrices, whose mechanical properties can be influenced by applying a magnetic field. Main parameters which determine the behavior of these smart materials are the concentration of the magnetic particles and the mechanical stiffness of the elastomer matrix. The viscoelastic properties of silicone-based MR elastomers are outlined in terms of their storage and loss moduli. The mechanical behavior of the material is also influenced by a magnetic field during the curing of the elastomer matrix, which leads to materials with anisotropic microstructures. The storage modulus of soft elastomer matrix composites can be increased in the presence of a magnetic field by significantly more than one order of magnitude or several hundreds of kPa. The relative increase exceeds that of all previously reported data. A shape memory effect, i. e. the deformation of an MR elastomer in a magnetic field and its return to original shape on cessasion of the magnetic field, is described.

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.

scholarly journals Controllable Magnetoactive Polymer Conduit

2018 ◽  
Vol 12 (1) ◽  
pp. 192-200
Author(s):  
A. Diermeier ◽  
D. Sindersberger ◽  
L. Krenkel ◽  
X. C. Rosell ◽  
G. J. Monkman
Keyword(s):  
Magnetic Field ◽  
Smart Materials ◽  
Kinematic Viscosity ◽  
Magnetic Particles ◽  
Mechanical Characteristics ◽  
Control Strategies ◽  
Tube System ◽  
Shear Moduli ◽  
Magnetic Field Homogeneity ◽  
Field Homogeneity

Objective: Magneto-active Polymers (MAP) are smart materials whose mechanical characteristics, such as elastic and shear moduli, may be controllable by means of an externally applied magnetic field. Methods: Various additives may be used to influence the characteristics of the polymer matrix whilst a suspension of soft and/or hard magnetic particles determine the magnetic properties of the composite. Both pre-cure and post-cure magnetization is possible. Results: A range of control strategies have been investigated for evaluation of the system using fluids of differing kinematic viscosity. Conclusion: Depending on the degree of magnetic field homogeneity, magneto-deformation and magnetostriction contribute to MAP actuation. This paper presents a novel application in the form of a peristaltic MAP tube system, applicable to flow control and pumping of hemorheological fluids in blood circulatory systems for biomedical research purposes.

scholarly journals Magnetic Field-Dependent Reversal Effect of the Electromagnet- Induced Normal Stress of Magnetorheological Materials

2020 ◽  
Vol 1 (4) ◽  
pp. 1 ◽  
Author(s):  
Taixiang Liu ◽  
Yangguang Xu ◽  
Ke Yang ◽  
Lianghong Yan ◽  
Beicong Huang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Normal Stress ◽  
Applied Magnetic Field ◽  
Smart Materials ◽  
Uniform Magnetic Field ◽  
Magnetic Particles ◽  
Reversal Effect ◽  
Field Dependent

Magnetorheological (MR) materials are a type of magnetoactive smart materials, whose physical or mechanical properties can be altered by applying a magnetic field. In usual, MR materials can be prepared by mixing magnetic particles into non-magnetic matrices. In this work, the electromagnet-induced (or non-uniform magnetic field-induced) normal stress of MR materials is studied. It shows that the stress does not vary monotonically along with the enhancement of the applied magnetic field. There exists a field-dependent reversal effect of the variation of the stress. The reversal effect is thought resulting from that the ratio of interparticle repellent of parallel magnetic particles to the particle-electromagnet attraction gets enlarged along with the enhancement of the field.

A New Device for Measuring the Viscoelastic Properties of Hydrated Matrix Gels

2002 ◽  
Vol 124 (2) ◽  
pp. 145-154 ◽  
Author(s):  
Jeffrey W. Parsons ◽  
Robin N. Coger
Keyword(s):  
Material Properties ◽  
Viscoelastic Properties ◽  
Type I Collagen ◽  
Bulk Material ◽  
Type I ◽  
New Device ◽  
Storage And Loss Moduli ◽  
Order Of Magnitude ◽  
Stiffness And Damping ◽  
Surrounding Fluid

Determinations of the viscoelastic properties of extracellular matrices (ECMs) are becoming increasingly important for accurate predictive modeling of biological systems. Since the interactions of the cells with the ECM and surrounding fluid (e.g., blood, media) each affect cell behavior; it is advantageous to evaluate the ECM’s material properties in the presence of the hydrating fluid. Conventional rheometry methods evaluate the bulk material properties of gel materials while displacing the hydrating liquid film. Such systems are therefore nonideal for testing materials such as ECMs, whose properties change with dehydration. The new, patent pending, piezoelectrically actuated linear rheometer is designed to eliminate this problem. It uses a single cantilever to apply an oscillating load to the gel and to sense the gel’s deflection. Composed of two thin film piezopolymer layers, the cantilever uses one layer as the actuator, and the second piezopolymer layer to measure the lateral movement of its attached probe. The viscoelastic nature of the ECM adds stiffness and damping to the system, resulting in the attenuation and phase shift of the sensor’s output voltage. From these parameters, the ECM’s shear storage and loss moduli are then determined. Initial tests on the BioMatrix I and type I collagen ECMs reveal that the first prototype of the piezoelectrically actuated linear rheometer is capable of accurately determining the trend and order of magnitude of an ECM’s viscoelastic properties. In this paper, details of the rheometer’s design and operating principles are described.

scholarly journals Giant Extensional Strain of Magnetoactive Elastomeric Cylinders in Uniform Magnetic Fields

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3297 ◽  
Author(s):  
Dmitry V. Saveliev ◽  
Inna A. Belyaeva ◽  
Dmitry V. Chashin ◽  
Leonid Y. Fetisov ◽  
Dirk Romeis ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Aspect Ratio ◽  
Smart Materials ◽  
Magnetic Particles ◽  
Sample Composition ◽  
Deformation Properties ◽  
Extensional Strain ◽  
The Impact ◽  
Macroscopic Shape

Elongations of magnetoactive elastomers (MAEs) under ascending–descending uniform magnetic fields were studied experimentally using a laboratory apparatus specifically designed to measure large extensional strains (up to 20%) in compliant MAEs. In the literature, such a phenomenon is usually denoted as giant magnetostriction. The synthesized cylindrical MAE samples were based on polydimethylsiloxane matrices filled with micrometer-sized particles of carbonyl iron. The impact of both the macroscopic shape factor of the samples and their magneto-mechanical characteristics were evaluated. For this purpose, the aspect ratio of the MAE cylindrical samples, the concentration of magnetic particles in MAEs and the effective shear modulus were systematically varied. It was shown that the magnetically induced elongation of MAE cylinders in the maximum magnetic field of about 400 kA/m, applied along the cylinder axis, grew with the increasing aspect ratio. The effect of the sample composition is discussed in terms of magnetic filler rearrangements in magnetic fields and the observed experimental tendencies are rationalized by simple theoretical estimates. The obtained results can be used for the design of new smart materials with magnetic-field-controlled deformation properties, e.g., for soft robotics.

scholarly journals Magnetorheological Elastomers: Fabrication, Characteristics, and Applications

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4597
Author(s):  
Sung Kang ◽  
Kisuk Choi ◽  
Jae-Do Nam ◽  
Hyoung Choi
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Viscoelastic Properties ◽  
Magnetic Particles ◽  
Advanced Materials ◽  
Vibration Absorber ◽  
Solid Base ◽  
Magnetorheological Elastomers ◽  
Electromagnetic Wave Absorption ◽  
Elastomeric Materials

Magnetorheological (MR) elastomers become one of the most powerful smart and advanced materials that can be tuned reversibly, finely, and quickly in terms of their mechanical and viscoelastic properties by an input magnetic field. They are composite materials in which magnetizable particles are dispersed in solid base elastomers. Their distinctive behaviors are relying on the type and size of dispersed magnetic particles, the type of elastomer matrix, and the type of non-magnetic fillers such as plasticizer, carbon black, and crosslink agent. With these controllable characteristics, they can be applied to various applications such as vibration absorber, isolator, magnetoresistor, and electromagnetic wave absorption. This review provides a summary of the fabrication, properties, and applications of MR elastomers made of various elastomeric materials.

Shear Vibration Property of Magnetically-Responsive Gels in Magnetically Open Looped System

2013 ◽  
Author(s):  
Hiroshi Nasuno ◽  
Yotsugi Shibuya ◽  
Hiroshi Sodeyama ◽  
Katsuaki Sunakoda
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Magnetic Particles ◽  
Deformation Characteristics ◽  
Dynamic Shear ◽  
Force Relation ◽  
Shear Vibration ◽  
Storage And Loss Moduli ◽  
Displacement Force ◽  
Different Thickness

This paper deals with dynamic shear deformation characteristics of magnetically-responsive (MR) gels under inhomogeneous magnetic fields. Magnetic particles as Fe-Si-Ni type which is generally known as permalloy, were dispersed in silicone gel to prepare the MR composite. An external magnetic field is applied only to one side of the MR gel by using magnetically open-looped circuit, and different excitation frequencies with constant shear strain amplitude is also applied to MR gels with each different thickness. The shear displacement-force relation of MR gel in open-looped circuit were observed, and mechanical properties such as storage and loss moduli were evaluated from experimental data. As a result, it is found that the characteristics change to a large extent depending on the applied magnetic field and the thickness of the MR gel.

Magnetorheological Elastomer based torsional vibration isolator for application in a prototype drilling shaft

2021 ◽  
pp. 146134842110446
Author(s):  
Thaer M. I. Syam ◽  
Asan G. A. Muthalif
Keyword(s):  
Magnetic Field ◽  
Torsional Vibration ◽  
Smart Materials ◽  
Magnetic Particles ◽  
Vibration Isolation ◽  
Drill String ◽  
Vibration Isolator ◽  
Magnetorheological Elastomer ◽  
Rotational Vibration ◽  
Active Vibration

Smart materials properties are altered using external stimuli such as temperature, pressure and magnetic field. Magnetorheological Elastomer (MRE) is a type of smart composite material consisting of a polymer matrix embedded with ferromagnetic particles. In the presence of an external magnetic field, its mechanical properties, such as stiffness, change due to the interaction between the magnetic particles, which have applications in vibration isolation. Unwanted vibration in machines can cause severe damage and machine breakdown. In this work, a semi-active vibration isolator using MRE is proposed for a potential application in a drilling system to isolate the torsional vibration. The MRE was fabricated with a 35% mass fraction (MF) consisted of silicon rubber and iron particles. It was fitted with aluminium couplers and attached to the shaft (drill string) to study its efficiency in vibration isolation under a magnetic field. Two tests were conducted on the drilling prototype setup used in this work; the first test was a hammer impact test. The torsional transfer function TTF analysis showed that the system’s natural frequency has shifted from 13.9 Hz to 17.5 Hz by the influence of increasing magnetic field around the MRE. The results showed that the continuous rotational vibration amplitude of the prototype is attenuated by more than 40%.

Actuation Behavior in Patterned Magnetorheological Elastomers: Simulation, Experiment, and Modeling

2012 ◽  
Author(s):  
Paris von Lockette
Keyword(s):  
Magnetic Field ◽  
Smart Materials ◽  
Magnetic Particles ◽  
Constitutive Models ◽  
Barium Hexaferrite ◽  
Shear Stiffness ◽  
Silicone Elastomer ◽  
Dynamic Shear ◽  
Magnetorheological Elastomers ◽  
Magnetic Symmetry

Magnetorheological elastomers (MREs) are an emerging class of smart materials whose mechanical behavior varies in the presence of a magnetic field. Historically MREs have been comprised of soft-magnetic iron particles in a compliant matrix such as silicone elastomer. Numerous works have experimentally cataloged the MRE effect, or increase in shear stiffness, versus the applied field. Several other researchers have derived constitutive models for the large deformation behavior of MREs. In almost all cases the arrays of embedded particles, and or the particles themselves, are assumed magnetically symmetric with respect to the external magnetic field, i.e. the bulk materials exhibit magnetic symmetry in the given experimental or analytical configuration. In this work the author presents results of dynamic shear experiments, Lagrangian dynamic analysis, and static shear simulations on MRE material systems that exhibit broken magnetic symmetry. These new materials utilize barium hexaferrite powder as the magnetically anisotropic filler combined with a compliant silicone elastomer matrix. Simulations of representative laminate structures comprised of varied arrays of magnetic particles exhibit novel actuation behaviors including reversible shearing deformation, variable magnetostriction, and most surprisingly, piezomagnetism. Results of dynamic shear experiments and analytical modeling support predicted shearing actuation responses in MREs having broken symmetry and only in those systems.

Effects of an External Magnetic Field on Polymeric Foam-Ferromagnet Composites

2016 ◽  
Vol 97 ◽  
pp. 30-35
Author(s):  
Marco D'Auria ◽  
Valentina Volpe ◽  
Daniele Davino ◽  
Roberto Pantani ◽  
Luigi Sorrentino
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Strain Curve ◽  
Strengthening Effect ◽  
Mechanical Stiffness ◽  
Linear Elastic ◽  
Micro Particles ◽  
Measured Stress ◽  
Positive Variation ◽  
Particle Alignment

Composite lightweight materials based on a polymeric matrix with embedded magnetic micro-particles have been developed. The application of a magnetic field (MF) during the foaming of samples induced the alignment of magnetic particles along the MF lines, forming reinforcing chain-like structures. The presence of aligned micro-particles imparted an anisotropic mechanical behavior along the particle alignment direction, thus strongly improving mechanical stiffness and strength compared to randomly filled systems. The application of a MF on pre-strained samples during the magneto-mechanical characterization resulted in a direct relationship between the measured variation of the elastic modulus of the foam and the time dependent intensity of the applied MF (also for a magnetic field strength as low as 200 kA/m). In particular, all reinforced samples pre-strained in the linear elastic region of the stress-strain curve exhibited a magneto-strictive response (negative variation of the measured stress). On the contrary, a positive variation of the measured stress (strengthening effect) was detected in samples with aligned particles at pre-strains above the yield point. This behavior has been related to the tendency of chain-like aggregates in buckled cell edges to re-align along the MF lines.

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