Magnetostriction of Field-Structured Composites

2003 ◽  
Vol 785 ◽  
Author(s):  
James E. Martin ◽  
Robert A. Anderson ◽  
Gerald Gulley
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Structural Phase ◽  
Sensors And Actuators ◽  
Demagnetizing Field ◽  
New Class ◽  
Self Consistent Field ◽  
Principal Directions

ABSTRACTField-structured magnetic particle composites are an important new class of materials that have great potential as both sensors and actuators. These materials are synthesized by suspending magnetic particles in a polymeric resin and subjecting these to magnetic fields while the resin polymerizes. If a simple uniaxial magnetic field is used, the particles will form chains, yielding composites whose magnetic susceptibility is enhanced along a single direction. A biaxial magnetic field, comprised of two orthogonal ac fields, forms particle sheets, yielding composites whose magnetic susceptibility is enhanced along two principal directions. A balanced triaxial magnetic field can be used to enhance the susceptibility in all directions, and biased heterodyned triaxial magnetic fields are especially effective for producing composites with a greatly enhanced susceptibility along a single axis. Magnetostriction is quadratic in the susceptibility, so increasing the composite susceptibility is important to developing actuators that function well at modest fields. To investigate magnetostriction in these field-structured composites we have constructed a sensitive, constant-stress apparatus capable of 1 ppm strain resolution. The sample geometry is designed to minimize demagnetizing field effects. We have demonstrated field-structured composites with nearly 10,000 ppm strain, and have shown that at large magnetic fields a structural phase transition occurs within the composite. These experimental results are compared to microscopic, self-consistent field simulations of magnetostriction in these complex, disordered materials.

scholarly journals Optical Imaging of Magnetic Particle Cluster Oscillation and Rotation in Glycerol

2021 ◽  
Vol 7 (5) ◽  
pp. 82
Author(s):  
River Gassen ◽  
Dennis Thompkins ◽  
Austin Routt ◽  
Philippe Jones ◽  
Meghan Smith ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Magnetic Particle ◽  
Barium Hexaferrite ◽  
Optical Microscope ◽  
Simplified Model ◽  
Particle Cluster ◽  
Average Deviation ◽  
Cross Sectional

Magnetic particles have been evaluated for their biomedical applications as a drug delivery system to treat asthma and other lung diseases. In this study, ferromagnetic barium hexaferrite (BaFe12O19) and iron oxide (Fe3O4) particles were suspended in water or glycerol, as glycerol can be 1000 times more viscous than water. The particle concentration was 2.50 mg/mL for BaFe12O19 particle clusters and 1.00 mg/mL for Fe3O4 particle clusters. The magnetic particle cluster cross-sectional area ranged from 15 to 1000 μμm2, and the particle cluster diameter ranged from 5 to 45 μμm. The magnetic particle clusters were exposed to oscillating or rotating magnetic fields and imaged with an optical microscope. The oscillation frequency of the applied magnetic fields, which was created by homemade wire spools inserted into an optical microscope, ranged from 10 to 180 Hz. The magnetic field magnitudes varied from 0.25 to 9 mT. The minimum magnetic field required for particle cluster rotation or oscillation in glycerol was experimentally measured at different frequencies. The results are in qualitative agreement with a simplified model for single-domain magnetic particles, with an average deviation from the model of 1.7 ± 1.3. The observed difference may be accounted for by the fact that our simplified model does not include effects on particle cluster motion caused by randomly oriented domains in multi-domain magnetic particle clusters, irregular particle cluster size, or magnetic anisotropy, among other effects.

scholarly journals Railway Actuator Made of Magnetic Elastomers and Driven by a Magnetic Field

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1351 ◽  
Author(s):  
Yasuhiro Umehara ◽  
Yusuke Yamanaga ◽  
Shota Akama ◽  
Shunsuke Kato ◽  
Shogo Kamoshita ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Elastic Modulus ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Fine Particles ◽  
Lateral Force ◽  
Railway Vehicle ◽  
Compression Tests ◽  
Field Stress ◽  
Magnetic Elastomers

We fabricated a mono-link using bimodal magnetic elastomers that demonstrate drastic changes in the elastic modulus by magnetic fields. The magnetic elastomer is bimodal consisting of large magnetic particles and nonmagnetic fine particles. The storage modulus for bimodal magnetic elastomers was altered from 2.2 × 105 to 1.7 × 106 Pa by a magnetic field of 500 mT. Compression tests up to a strain of 20% also revealed that the on-field stress for the bimodal magnetic elastomer was 1.24 times higher than the off-field stress. The bimodal magnetic elastomer was synthesized for the mono-link and was mounted on the bogie of a railway vehicle. A running test exhibited that the wheel lateral force was reduced by 20% by applying a magnetic field of 390 mT.

Targeting Magnetic Nanoparticles in High Magnetic Fields for Drug Delivery Purposes

2004 ◽  
Vol 820 ◽  
Author(s):  
Ramazan Asmatulu ◽  
Richard.O. Claus ◽  
Judy S. Riffle ◽  
Michael Zalich
Keyword(s):  
Magnetic Field ◽  
Drug Delivery ◽  
Magnetic Nanoparticles ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Guidance System ◽  
Test Results ◽  
Test Parameters ◽  
Magnetic Guidance ◽  
The Magnetic Field

AbstractBiodegradable magnetic nanoparticles were synthesized using Poly(L-Lactic Acid) and magnetite nanoparticles (∼14 nm) at different dosages, and then these nanaoparticles (nanocomposites) and pure magnetic particles were targeted in external magnetic fields by changing the test parameters. The magnetic field test results showed that magnetic saturation, fluid speed, magnetic field distance and particle size were extremely effective for a magnetic guidance system that is needed for an effective drug delivery approach. Thus, it is assumed that such nanoparticles can carry drugs (chemotherapy) to be able to cure cancer tumors as well as many other diseases.

A variational calculation of magnetized correlated fermion system using a spin-dependent correlation: Application to liquid 3He

2015 ◽  
Vol 29 (07) ◽  
pp. 1550046 ◽  
Author(s):  
Gholam Hossein Bordbar ◽  
Mohammad Taghi Mohammadi Sabet
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Correlation Function ◽  
Magnetic Fields ◽  
Spin Correlation ◽  
Variational Calculation ◽  
Fermion System ◽  
Magnetic Instability ◽  
Spin Correlation Function ◽  
Dependent Correlation

In the presence of magnetic field, we have employed a spin-dependent correlation function to investigate the properties of liquid 3 He using the variational method based on the cluster expansion of the energy. It has been indicated that at all relevant magnetic fields and densities, the inclusion of spin-dependency for the correlation function leads to the lower magnitudes for the kinetic, magnetic and potential energies, and therefore the total energy of this system. We have seen that the spin–spin correlation affects the system to be less magnetized compared to the case in which we consider the spin-independent correlation, especially at low densities. In the case of spin–spin correlation function, our results show a maximum in the magnetic susceptibility, and therefore a meta-magnetic instability for the system for the magnetic fields in the range 50 T ≤ B ≤ 60 T . This behavior has not been observed in the case of spin-independent correlation.

Non-Equilibrium Magnetization of a Dilute Suspension of Magnetic Particles

2009 ◽  
Vol 152-153 ◽  
pp. 167-170 ◽  
Author(s):  
Alexander Tyatyushkin
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Heat Generation ◽  
Applied Magnetic Field ◽  
Single Particle ◽  
Uniform Magnetic Field ◽  
Magnetic Particles ◽  
Equilibrium Magnetization ◽  
Dilute Suspension ◽  
Generation Power

A suspension of magnetic particles in a viscous liquid magnetized in an alternating uniform magnetic field is theoretically studied. The suspension is regarded as so dilute that interaction of a single particle with the applied magnetic field can be considered without taking into account the influence of other particles. The complex magnetic susceptibility of the suspension is found as a function of the frequency of the applied magnetic field. The heat generation power density averaged over the period of the oscillations is calculated.

scholarly journals Experiments and Numerical Implementation of a Boundary Value Problem Involving a Magnetorheological Elastomer Layer Subjected to a Nonuniform Magnetic Field

2021 ◽  
Vol 88 (7) ◽  
Author(s):  
Charles Dorn ◽  
Laurence Bodelot ◽  
Kostas Danas
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Boundary Value Problem ◽  
Magnetic Particles ◽  
Boundary Value ◽  
Energetic Efficiency ◽  
Iron Core ◽  
Isotropic Layer ◽  
Magnetorheological Elastomer ◽  
Electromagnetic Coil

Abstract This study investigates experimentally and numerically the response of a magnetorheological elastomer (MRE) layer placed atop an electromagnetic coil. The MRE layer is deflected upon application of a current in the coil, which creates highly nonuniform magnetic fields. Isotropic and transversely isotropic layers (i.e., containing chains of magnetic particles) are tested experimentally, and the isotropic layer exhibits the largest deflection. To enhance the energetic efficiency of the model device, an iron core is introduced inside the electromagnetic coil, thereby leading to an increase in the resulting magnetic field near the center of the MRE layer. In parallel, the boundary value problem —including the MRE layer, the coil, the core (if present) and the surrounding air—is modeled numerically. For this, a magneto-mechanical, vector potential-based variational formulation is implemented in a standard three-dimensional finite element model at finite strains. For the material description, a recently proposed analytical homogenization-guided model is used to analyze the MRE in the “coil-only” configuration. It is then employed to predict the response of the layer in the “coil plus core” configuration, thus circumventing the need for a separate material characterization procedure. The proposed numerical simulation strategy provides a deeper understanding of the underlying complexity of the magnetic fields and of their interaction with the MRE layer. This study also reveals the importance of modeling the entire setup for predicting the response of MRE materials and, as a result, constitutes a step toward designing more efficient MRE-based devices.

Magnetic phenomena

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Flux Density ◽  
Magnetic Dipole ◽  
Electric Charge ◽  
Dipole Moments ◽  
Magnetic Flux Density

In this chapter we deal with a number of magnetic properties and their directional dependence: pyromagnetism, magnetic susceptibility, magnetoelectricity, and piezomagnetism. In the course of dealing with these properties, two new ideas are introduced: magnetic symmetry and axial tensors. Moving electric charge generates magnetic fields and magnetization. Macroscopically, an electric current i flowing in a coil of n turns per meter produces a magnetic field H = ni amperes/meter [A/m]. On the atomic scale, magnetization arises from unpaired electron spins and unbalanced electronic orbital motion. The weber [Wb] is the basic unit of magnetic charge m. The force between two magnetic charges m1 and m2 is where r is the separation distance and μ0 (=4π×10−7 H/m) is the permeability of vacuum. In a magnetic field H, magnetic charge experiences a force F = mH [N]. North and south poles (magnetic charges) separated by a distance r create magnetic dipole moments mr [Wb m]. Magnetic dipole moments provide a convenient way of picturing the atomistic origins arising from moving electric charge. Magnetization (I) is the magnetic dipole moment per unit volume and is expressed in units of Wb m/m3 = Wb/m2. The magnetic flux density (B = I + μ0H) is also in Wb/m2 and is analogous to the electric displacement D. All materials respond to magnetic fields, producing a magnetization I = χH, and a magnetic flux density B = μH where χ is the magnetic susceptibility and μ is the magnetic permeability. Both χ and μ are in henries/m (H/m). The permeability μ = χ + μ0 and is analogous to electric permittivity. χ and μ are sometimes expressed as dimensionless quantities (x ̅ and μ ̅ and ) like the dielectric constant, where = x ̅/μ0 and = μ ̅/μ0. Other magnetic properties will be defined later in the chapter. A schematic view of the submicroscopic origins of magnetic phenomena is presented in Fig. 14.1. Most materials are diamagnetic with only a weak magnetic response induced by an applied magnetic field.

Newton novel magnetic instrument. Potential application to unveil key questions as the origin of the Moon

2020 ◽  
Author(s):  
José Luis Mesa Uña ◽  
Marina Díaz Michelena ◽  
Francisco Javier de Frutos Hernánsanz ◽  
Claudio Aroca Hernández-Ros ◽  
Marina Pérez Jiménez ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Temporal Variations ◽  
Magnetic Characteristics ◽  
Potential Contribution ◽  
The European Union ◽  
The Moon ◽  
Lunar Crust ◽  
Sensors And Actuators ◽  
Earth Planet

<p>The main objective of this contribution is to present the evolution of NEWTON novel magnetic susceptometer for planetary exploration, a state of the art sensor for the measurement of the complex magnetic susceptibility developed in the frame of an EU H2020 funded project [1].</p><p>The magnetic susceptibility is a complex parameter dependent on the external magnetic field amplitude, direction and frequency. NEWTON susceptometer has been developed to determine the magnetic susceptibility of rocks and soils, with the capability to determine not only the real part but also the imaginary part of the susceptibility.</p><p>The calibration and validation process for the susceptometer prototype casted very good results in comparison with other commercial and high resolution laboratory devices, reaching a resolution in the order of χ = 10<sup>−4</sup> (I.S. Vol. Susceptibility), representative of Earth, Moon and Mars rocks. The critical parts of the prototype have been subjected to different tests, i.e. vibration and TVT, to verify the capability to withstand the hard environmental conditions of interplanetary missions.</p><p>In this work we discuss the potential contribution of NEWTON instrument on the technical and scientific objectives achievement in future investigations on the Moon, either as payload during in-situ exploration with rovers or in sample return missions, providing a useful tool for fast in place sample analysis.</p><p>There are still open questions regarding Moon’s magnetic field and geological characteristics of the satellite. Most hypotheses to explain the magnetic characteristics and anomalies on the lunar surface invoke a thermally driven core dynamo during its Pre-Nectarian and Nectarian history [2]. However, this theory is problematical given the small size of the core and the required strong magnetic field strength of an ancient dynamo. Further investigations on the lunar samples from missions [3] indicate ancient magnetic fields with intensities of <1 to 120 μT for the period between 4.2 to 4.0 Ga. This huge range of intensities may indicate that the Moon’s magnetic field experienced extreme high temporal variations [2]. Even if considering large uncertainties, dynamo models should consider paleointensities of at least ~35 μT for this high-field period.</p><p>The use of scientific instruments like NEWTON susceptometer in rover exploration missions could shed some light on the ancient dynamo magnetic field, the magnetic and mineral composition of the lunar crust and other unanswered questions from the Moon.</p><p>Acknowledgements:</p><p>This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 730041 and the Spanish Programme of Research, Development and Innovation oriented to the challenges of the society under grant ESP2017-88930-R.</p><p> </p><p><strong>References:</strong></p><p>[1] M.Diaz Michelena, J.L Mesa Uña, M. Perez Jimenez, M. Maicas Ramos, P. Cobos Arribas, C. Aroca Hernandez-Ros, Sensors and Actuators, A: Physical, volume 263, pages 471-479 (2017)</p><p>[2] Tikoo, S.M., Weiss, B.P., Cassata, W.S., Shuser, D.L., Gattacceca, J., Lima, E.A., Suavet, C., Nimmo, F. & Fuller, M.D. Earth Planet. Sci. Lett., 404: 89-97 (2014)</p><p>[3] Tsunakawa, H., Takahashi, F., Shimizu, H., Shibuya, H., & Matsushima, M. Icarus 228: 35-53 (2014).</p><p>[3] Fuller, M. (1974). Reviews of Geophysics, 12 – 1, 101-103 (1974)</p>

Theoretical Modeling and Simulations of Magnetic Fluids in Gradient Magnetic Fields

2010 ◽  
Vol 146-147 ◽  
pp. 1510-1513
Author(s):  
Xiao Ling Peng ◽  
Xiao Yang ◽  
Hai Biao Wei ◽  
Rui Ping Yue ◽  
Hong Liang Ge
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Gradient ◽  
Magnetic Particles ◽  
Magnetic Field Gradient ◽  
Magnetic Fluids ◽  
Gradient Distribution ◽  
Particle Distributions ◽  
The Right ◽  
Pulsed Fields

When a magnetic field is applied to magnetic fluids (MF), various structures of MF are formed: chain-like structures in low fields, columnar, lamellar and striped structures in high fields, ellipsoidal structures in pulsed fields, and layered structures in rotating fields. The inner structures and particle distributions of MF in gradient magnetic fields are quite interesting, but very few works have been done on this. In the present study, the effects of magnetic field gradient on the structures of MF are investigated using a two-dimensional Monte Carlo simulation. The results show that a gradient distribution of magnetic particles is formed under gradient magnetic fields. Moreover, with increasing the field gradient, more magnetic particles are pushed to the right region and particle distribution changes from grass-like clusters to needle-like ones.

Influence of the Magnetic Interaction among Particles on Distributions of Magnetic Fluids Using Computer Simulations

2010 ◽  
Vol 150-151 ◽  
pp. 1595-1598
Author(s):  
Xiao Ling Peng ◽  
Hai Biao Wei ◽  
Xiao Yang ◽  
Rui Ping Yue ◽  
Hong Liang Ge
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Particle Distribution ◽  
Magnetic Field Gradient ◽  
Magnetic Interaction ◽  
Magnetic Fluids ◽  
Colloidal Dispersion ◽  
Gradient Distribution ◽  
Particle Distributions

Magnetic fluid is a stable colloidal dispersion of ferromagnetic particles in a liquid carrier. Once a magnetic field is applied to magnetic fluids (MF), various structures of MF are formed. A detailed understanding of structures and particle distributions in gradient magnetic fields is much important. But very few works have been done on this. In the present study, the effects of magnetic field gradient and magnetic interaction among magnetic particles on the structures of MF are investigated using a two-dimensional Monte Carlo simulation. The results show that a gradient distribution of magnetic particles is formed under gradient magnetic fields. However, as the interaction between magnetic particles increases, the distribution gradient decreases, accompanied by the formation of chain-like clusters. Moreover, with increasing the magnetic interaction, particle distribution changes from grass-like clusters to needle-like ones.

Sign in / Sign up

Export Citation Format

Share Document