The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

Yuping Wu - One of the best experts on this subject based on the ideXlab platform.

  • influence of Demagnetizing Field on the permeability of soft magnetic composites
    Journal of Magnetism and Magnetic Materials, 2006
    Co-Authors: Zhaoliang Li, Linfeng Chen, Yuping Wu
    Abstract:

    The influence of Demagnetizing Field on the effective permeability of magnetic composites has been investigated. A theoretical expression of the effective permeability has been obtained and discussed according to four typical composites with spheres, needles, flakes, and aligned prolate ellipsoidal particles. The results indicate that the Demagnetizing Field within the particles can reduce the effective permeability significantly. In order to increase the effective permeability, it is necessary to decrease the Demagnetizing Field within the particles. A linear relationship between effective permeability and volume fraction is also observed for composites filled with spherical particles at low volume fraction.

Jorg Petrasch - One of the best experts on this subject based on the ideXlab platform.

  • tomography based numerical simulation of the Demagnetizing Field in soft magnetic composites
    Journal of Applied Physics, 2015
    Co-Authors: Stefan Arzbacher, Peter Amann, Bernd Weidenfeller, Thomas Loerting, Alexander Ostermann, Jorg Petrasch
    Abstract:

    The magneto-static behaviour of soft magnetic composites (SMCs) is investigated using tomography based direct numerical simulation. The microgeometry crucially affects the magnetic properties of the composite since a geometry dependent Demagnetizing Field is established inside the composite, which lowers the magnetic permeability. We determine the magnetic Field information inside the SMC using direct numerical simulation of the magnetic Field based on high resolution micro-computed tomography data of the SMC's microstructure as well as artificially generated data made of statistically homogeneous systems of identical fully penetrable spheres and prolate spheroids. Quasi-static electromagnetic behaviour and linear material response are assumed. The 3D magnetostatic Maxwell equations are solved using Whitney finite elements. Simulations show that clustering and percolation behaviour determine the Demagnetizing factor of SMCs rather than the particle shape. The Demagnetizing factor correlates with the slope of a 2-point probability function at its origin, which is related to the specific surface area of the SMC. Comparison with experimental results indicates that the relatively low permeability of SMCs cannot be explained by Demagnetizing effects alone and suggests that the permeability of SMC particles has to be orders of magnitude smaller than the bulk permeability of the particle material.

Zhaoliang Li - One of the best experts on this subject based on the ideXlab platform.

  • influence of Demagnetizing Field on the permeability of soft magnetic composites
    Journal of Magnetism and Magnetic Materials, 2006
    Co-Authors: Zhaoliang Li, Linfeng Chen, Yuping Wu
    Abstract:

    The influence of Demagnetizing Field on the effective permeability of magnetic composites has been investigated. A theoretical expression of the effective permeability has been obtained and discussed according to four typical composites with spheres, needles, flakes, and aligned prolate ellipsoidal particles. The results indicate that the Demagnetizing Field within the particles can reduce the effective permeability significantly. In order to increase the effective permeability, it is necessary to decrease the Demagnetizing Field within the particles. A linear relationship between effective permeability and volume fraction is also observed for composites filled with spherical particles at low volume fraction.

Stefan Arzbacher - One of the best experts on this subject based on the ideXlab platform.

  • tomography based numerical simulation of the Demagnetizing Field in soft magnetic composites
    Journal of Applied Physics, 2015
    Co-Authors: Stefan Arzbacher, Peter Amann, Bernd Weidenfeller, Thomas Loerting, Alexander Ostermann, Jorg Petrasch
    Abstract:

    The magneto-static behaviour of soft magnetic composites (SMCs) is investigated using tomography based direct numerical simulation. The microgeometry crucially affects the magnetic properties of the composite since a geometry dependent Demagnetizing Field is established inside the composite, which lowers the magnetic permeability. We determine the magnetic Field information inside the SMC using direct numerical simulation of the magnetic Field based on high resolution micro-computed tomography data of the SMC's microstructure as well as artificially generated data made of statistically homogeneous systems of identical fully penetrable spheres and prolate spheroids. Quasi-static electromagnetic behaviour and linear material response are assumed. The 3D magnetostatic Maxwell equations are solved using Whitney finite elements. Simulations show that clustering and percolation behaviour determine the Demagnetizing factor of SMCs rather than the particle shape. The Demagnetizing factor correlates with the slope of a 2-point probability function at its origin, which is related to the specific surface area of the SMC. Comparison with experimental results indicates that the relatively low permeability of SMCs cannot be explained by Demagnetizing effects alone and suggests that the permeability of SMC particles has to be orders of magnitude smaller than the bulk permeability of the particle material.

K Ishiyama - One of the best experts on this subject based on the ideXlab platform.

  • influence of Demagnetizing Field on thin film gmi magnetic sensor elements with uniaxial magnetic anisotropy
    Sensors and Actuators A-physical, 2015
    Co-Authors: Hiroaki Kikuchi, Shingo Kamata, Tomoo Nakai, S Hashi, K Ishiyama
    Abstract:

    Abstract We investigated the dependence of Demagnetizing effect on the giant magnetoimpedance (GMI) properties of elements fabricated using a thin film with uniaxial magnetic anisotropy. Using photolithography techniques, we fabricated two types of sensor elements. One type has a typical GMI configuration, i.e., the easy axis is parallel to the width of the sensor element, whereas the other type has an inclined easy axis. In sensors with a typical GMI configuration, the impedance changes and sensitivity at the edges of the elements are reduced relative to the middle sections, whereas the discontinuous impedance jump is substantially reduced or modified in sensors with inclined easy-axis GMI elements. This divergence in behavior can be explained by the differences in the distribution of Demagnetizing Fields within the respective element types. Because the Demagnetizing Field has an increased gradient of growth at the edge of an element, rotation or movement of the magnetization moment becomes increasingly modified. We confirmed the changes in the distribution of the Demagnetizing Field within the element using magnetic-Field analysis and confirmed by domain observation that nonuniform magnetic domain movement occurs at the edge of the element. The change in the direction-to-gain ratio associated with higher element sensitivity is also discussed, and a method to effectively utilize the discontinuous jump is introduced. Only the central part of the element should be used to eliminate the influence due to the distribution of the Demagnetizing Field.

  • Improvement of Stepped Magnetoimpedance Properties by Controlling the Demagnetizing Effect
    IEEE Transactions on Magnetics, 2015
    Co-Authors: H. Kikuchi, S Hashi, S. Kamata, S. Oe, T. Nakai, K Ishiyama
    Abstract:

    We investigated the effects of controlling the distribution of the Demagnetizing Field on the impedance profiles of stepped giant magnetoimpedance elements. Elements with an ellipsoidal shape were adopted to improve the properties in discontinuous impedance jumps, as the Demagnetizing Field is expected to be uniform in an ellipsoid. The impedance jumps in the ellipsoidal elements became sharper and more abrupt, and the height ratio improved by 3-4 times compared with the ratio of the conventional rectangular elements. The observed domain structures propagated from the edge to the center in the rectangular elements, which is explained on the basis of the calculated distribution of the Demagnetizing factor. On the other hand, all the domains appeared or disappeared in the ellipsoidal elements, indicating that the Demagnetizing factor is nearly constant in the elements. The results contribute to a miniaturization of the element in order to keep the abrupt discontinuous impedance.