scholarly journals Field-Dependent Stiffness of a Soft Structure Fabricated from Magnetic-Responsive Materials: Magnetorheological Elastomer and Fluid

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 953 ◽  
Author(s):  
Byung-Keun Song ◽  
Ji-Young Yoon ◽  
Seong-Woo Hong ◽  
Seung-Bok Choi
Keyword(s):  
Large Deformation ◽  
Permanent Magnets ◽  
Skin Layer ◽  
Magnetic Flux Density ◽  
Magnetorheological Elastomer ◽  
Deformation Region ◽  
Responsive Materials ◽  
Magnetic Stimulus ◽  
Two Samples ◽  
Field Dependent

A very flexible structure with a tunable stiffness controlled by an external magnetic stimulus is presented. The proposed structure is fabricated using two magnetic-responsive materials, namely a magnetorheological elastomer (MRE) as a skin layer and a magnetorheological fluid (MRF) as a core to fill the void channels of the skin layer. After briefly describing the field-dependent material characteristics of the MRE and MRF, the fabrication procedures of the structure are provided in detail. The MRE skin layer is produced using a precise mold with rectangular void channels to hold the MRF. Two samples are produced, namely with and without MRF, to evaluate the stiffness change attributed to the MRF. A magnetic field is generated using two permanent magnets attached to a specialized jig in a universal tensile machine. The force-displacement relationship of the two samples are measured as a function of magnetic flux density. Stiffness change is analyzed at two different regions, namely a small and large deformation region. The sample with MRF exhibits much higher stiffness increases in the small deformation region than the sample without MRF. Furthermore, the stiffness of the sample with MRF also increases in the large deformation region, while the stiffness of the sample without MRF remains constant. The inherent and advantageous characteristics of the proposed structure are demonstrated through two conceptual applications, namely a haptic rollable keyboard and a smart braille watch.

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

Development and Modeling of a Highly-Adjustable Base Isolator Utilizing Magnetorheological Elastomer

2013 ◽  
Author(s):  
Yancheng Li ◽  
Jianchun Li
Keyword(s):  
Analytical Model ◽  
Seismic Isolation ◽  
Large Scale ◽  
Lateral Stiffness ◽  
Magnetorheological Elastomer ◽  
Isolation System ◽  
Vertical Loading ◽  
Base Isolator ◽  
Field Dependent ◽  
Dependent Property

This paper presents a recent research breakthrough on the development of a novel adaptive seismic isolation system as the quest for seismic protection for civil structures, utilizing the field-dependent property of the magnetorheological elastomer (MRE). A highly-adjustable MRE base isolator was developed as the key element to form smart seismic isolation system. The novel isolator contains unique laminated structure of steel and MRE layers, which enable its large-scale civil engineering applications, and a solenoid to provide sufficient and uniform magnetic field for energizing the field-dependent property of MR elastomers. With the controllable shear modulus/damping of the MR elastomer, the developed adaptive base isolator possesses a controllable lateral stiffness while maintaining adequate vertical loading capacity. Experimental results show that the prototypical MRE base isolator provides amazing increase of lateral stiffness up to 1630%. Such range of increase of the controllable stiffness of the base isolator makes it highly practical for developing new adaptive base isolation system utilizing either semi-active or smart passive controls. To facilitate the structural control development using the adaptive MRE base isolator, an analytical model was developed to stimulate its behaviors. Comparison between the analytical model and experimental data proves the effectiveness of such model in reproducing the behavior of MRE base isolator, including the observed strain stiffening effect.

scholarly journals Analysis of a Permanent-Magnet Brushless DC Motor with Fixed Dimensions

2010 ◽  
Vol 26 (1) ◽  
pp. 78-81
Author(s):  
Uldis Brakanskis ◽  
Janis Dirba ◽  
Ludmila Kukjane ◽  
Viesturs Drava
Keyword(s):  
Magnetic Flux ◽  
Permanent Magnet ◽  
Permanent Magnets ◽  
Dc Motor ◽  
Magnetic Flux Density ◽  
Brushless Dc Motor ◽  
Outer Diameter ◽  
Zone Length ◽  
Brushless Dc ◽  
Permanent Magnet Brushless Dc

Analysis of a Permanent-Magnet Brushless DC Motor with Fixed DimensionsThe purpose of this paper is to describe the analysis of a permanent-magnet brushless DC motor with fixed outer diameter and active zone length. The influence of air gap, material of permanent magnets and their size on the magnetic flux density of the machine and magnetic flux is analyzed. The work presents the calculations of two programs, the comparison of the results and the most suitable combination of factors that has been found.

scholarly journals The Air Gap and Angle Optimization in the Axial Flux Permanent Magnet Motor

1970 ◽  
Vol 110 (4) ◽  
pp. 25-29 ◽  
Author(s):  
C. Akuner ◽  
E. Huner
Keyword(s):  
Magnetic Flux ◽  
Permanent Magnet ◽  
Permanent Magnets ◽  
Air Gap ◽  
Magnetic Flux Density ◽  
Permanent Magnet Motor ◽  
Axial Flux ◽  
Flux Change ◽  
Torque Values ◽  
The Impact

In this study, the axial flux permanent magnet motor and the length range of the air gap between rotors was analyzed and the appropriate length obtained. NdFeB permanent magnets were used in this study. Permanent magnets can change the characteristics of the motor's torque. However, the distance between permanent magnets and the air gap will remain constant for each magnet. The impact of different magnet angles for the axial flux permanent magnet motor and other motor parameters was examined. To this aim, the different angles and torque values of the magnetic flux density were calculated using the finite element method of analysis with the help of Maxwell 3D software. Maximum torque was obtained with magnet angles of 21°, 26°, 31.4°, and 34.4°. Additionally, an important parameter for the axial flux permanent magnet motor in terms of the air gap flux was analyzed. Minimum flux change was obtained with a magnet angle of 26°. The magnetic flux of the magnet-to-air-gap is under 0.5 tesla. Given the height of the coil, the magnet-to-air-gap distance most suitable for the axial flux permanent magnet motor was 4 mm. Ill. 11, bibl. 4, tabl. 2 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.280

ROOM TEMPERATURE MAGNETIC ANOMALIES IN BENZENE TREATED Bi–Pb–Sr–Ca–Cu–O POWDER

1991 ◽  
Vol 05 (21) ◽  
pp. 1447-1456 ◽  
Author(s):  
A. R. HARUTUNYAN ◽  
L. S. GRIGORYAN ◽  
A. S. KUZANYAN ◽  
A. A. KUZNETSOV ◽  
A. A. TERENTIEV ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Chemical Composition ◽  
Room Temperature ◽  
Microprobe Analysis ◽  
Magnetic Anomalies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Two Samples ◽  
Field Dependent ◽  
History Of

Two samples of benzene-treated Bi–Pb–Sr–Ca–Cu–O powder exhibited at 300 K magnetic field dependent diamagnetism and magnetization irreversibility. The treatment with benzene resulted also in the appearance of microwave absorption at low magnetic fields, while is sensitive to magnetic history of the sample. From X-ray diffraction data one can see that upon benzene treatment the reflections of 85 K and 110 K phases do not change practically, but a series of new reflections appeared, indicating a lattice modulation with 4.9 nm periodicity. A microprobe analysis revealed substantial inhomogeneity of chemical composition across the samples. The room temperature anomalies were weakened in one sample and vanished in the second upon thermal cycling.

scholarly journals Mitigation Method of Slot Harmonic Cogging Torque Considering Unevenly Magnetized Permanent Magnets in PMSM

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3887
Author(s):  
Jeong ◽  
Lee ◽  
Hur
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Permanent Magnet Synchronous Motor ◽  
Harmonic Component ◽  
Magnetic Flux Density ◽  
Element Analysis ◽  
Cogging Torque ◽  
Maxwell Stress Tensor ◽  
The Finite Element Analysis ◽  
Harmonic Components

This paper presents a mitigation method of slot harmonic cogging torque considering unevenly magnetized magnets in a permanent magnet synchronous motor. In previous studies, it has been confirmed that non-uniformly magnetized permanent magnets cause an unexpected increase of cogging torque because of additional slot harmonic components. However, these studies did not offer a countermeasure against it. First, in this study, the relationship between the residual magnetic flux density of the permanent magnet and the cogging torque is derived from the basic form of the Maxwell stress tensor equation. Second, the principle of the slot harmonic cogging torque generation is explained qualitatively, and the mitigation method of the slot harmonic component is proposed. Finally, the proposed method is verified with the finite element analysis and experimental results.

scholarly journals An Analytical–Experimental Approach to Quantifying the Effects of Static Magnetic Fields for Cell Culture Applications

2020 ◽  
Vol 10 (2) ◽  
pp. 531
Author(s):  
Pablo Ferrada ◽  
Sebastián Rodríguez ◽  
Génesis Serrano ◽  
Carol Miranda-Ostojic ◽  
Alejandro Maureira ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Permanent Magnets ◽  
Bubbly Flow ◽  
Scenedesmus Obliquus ◽  
Relative Difference ◽  
Magnetic Flux Density ◽  
The South ◽  
Nannochloropsis Gaditana ◽  
Static Magnetic Fields ◽  
The North

This work aimed to study the effects of static magnetic fields (SMFs) on cell cultures. A glass flask was filled with a liquid medium, which was surrounded by permanent magnets. Air was introduced through a tube to inject bubbles. Two magnet configurations, north and south, were used as perturbation. Scenedesmus obliquus and Nannochloropsis gaditana, growing in Medium 1 and 2, were subjected to the bubbly flow and SMFs. Differences between media were mainly due to conductivity (0.09 S/m for Medium 1 and 4.3 S/m for Medium 2). Joule dissipation ( P ) increased with the magnetic flux density ( B 0 ), being 4 orders of magnitude higher in Medium 2 than in 1. Conversely, the time constant ( τ P ) depended on B 0 , being nearly constant for Medium 1 and decreasing at 449 s/T for Medium 2. Dissipation occurred with the same τ P (235 s) in Medium 1 and 2 at B 0 = 0.5 T. In Species 1, the SMF effect was inhibitory. For Species 2, a higher enzymatic activity was observed. For superoxide dismutase, the relative difference was 78% with the north and 115% with the south configuration compared to the control values. For the catalase, differences of 29% with the north and 23% with the south configuration compared to control condition were obtained.

Platform Design for Characterizing Shear Force Produced by Magnetized Magnetorheological Fluid

2019 ◽  
Author(s):  
Ping-Hsun Lee ◽  
Jen-Yuan (James) Chang
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Yield Stress ◽  
Flux Density ◽  
Shear Force ◽  
Permanent Magnets ◽  
Magnetic Flux Density ◽  
Finite Element Method Result ◽  
Mr Fluid ◽  
The Magnetic Field

Abstract In this paper we proposed a platform for measuring shear force of magnetorheological (MR) fluid by which the relationship of yield stress and magnetic flux density of specific material can be determined. The device consisted of a rotatable center tube in a frame body and the magnetic field was provided by two blocks of permanent magnets placed oppositely outside the frame body. The magnitude and direction of the magnetic field were manipulated by changing the distance of the two permanent magnets from the frame body and rotating the center tube, respectively. For determining the magnetic field of the device, we adopted an effective method by fitting the FEM (finite element method) result to the measured one and then rebuilt the absent components to approximate the magnetic field, which was hardly to be measured simultaneously as different device setup were required. With the proposed platform and analytical methods, the drawing shear force and the corresponding yield stress contributed by MR fluid could be evaluated in respect to the magnitude and direction of given magnetic flux density with acceptable accuracy for specific designing purposes without a large, complex, and expensive instrument.

scholarly journals A Magneto-Hyperelastic Model for Silicone Rubber-Based Isotropic Magnetorheological Elastomer under Quasi-Static Compressive Loading

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2435
Author(s):  
Yanliang Qiao ◽  
Jiangtao Zhang ◽  
Mei Zhang ◽  
Lisheng Liu ◽  
Pengcheng Zhai
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Silicone Rubber ◽  
Experimental Results ◽  
Magnetic Flux Density ◽  
Magnetorheological Elastomer ◽  
Static Compression ◽  
Compression Property ◽  
Hyperelastic Model ◽  
Quasi Static Compression

A new magneto-hyperelastic model was developed to describe the quasi-static compression behavior of silicone rubber-based isotropic magnetorheological elastomer (MRE) in this work. The magnetization property of MRE was characterized by a vibrating sample magnetometer (VSM), and the quasi-static compression property under different magnetic fields was tested by using a universal testing machine equipped with a magnetic field accessory. Experimental results suggested that the stiffness of the isotropic MRE increased with the magnetic flux density within the tested range. Based on experimental results, a new magneto-hyperelastic model was established by coupling the Ogden hyperelastic model, the magnetization model and the magneto-induced modulus model based on a magnetic dipole theory. The results show that the proposed new model can accurately predict the quasi-static compression property of the isotropic MRE under the tested magnetic flux density and strain ranges using only three model parameters.

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