scholarly journals II. The measurement of magnetic hysteresis

1902 ◽  
Vol 198 (300-311) ◽  
pp. 33-104 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Magnetic Hysteresis ◽  
Physical Processes ◽  
Mathematical Expressions ◽  
Sheet Iron ◽  
Standard Specimens ◽  
Simple Instrument ◽  
Energy Dissipated

1. Two ideal physical processes have been devised as the foundations of two methods of deducing mathematical expressions for the energy dissipated in magnetic material through magnetic hysteresis; these processes are due to Professor E. Warburg and to the late Dr. J. Hopkinson. In Warburg’s theory the specimen, in the form of a slender wire, is placed in a magnetic field due to a pair of permanent magnets so arranged as to produce magnetic force parallel to the length of the specimen. The mechanical work spent in moving these magnets through such a cycle of changes of position, that the iron is subjected to a cycle of magnetic changes, is clearly equal to the energy dissipated on account of magnetic hysteresis in the specimen. In terms of the magnetic quantities the energy dissipated per cub. centim. per cycle is — ∫I d H or ∫H d I ergs, where H is the magnetic force and I the intensity of magnetisation. Professor J. A. Ewing has applied the principle involved in Warburg’s theory to the design of a simple instrument by which the hysteresis of any specimen of sheet iron (for the range of induction B = 4000 to B = - 4000 C. G. S. units approximately) is determined by comparison with two standard specimens supplied with the instrument, and previously tested for hysteresis by the ballistic method. The principle has also been employed by W. S. Franklin, by H. S. Webb, and by G. L. W. Gill to obtain absolute determinations of hysteresis.

II. Magnetic qualities of iron

1894 ◽  
Vol 54 (326-330) ◽  
pp. 75-77 ◽  
Keyword(s):  
Magnetic Induction ◽  
Magnetic Force ◽  
Magnetic Hysteresis ◽  
Iron Wire ◽  
Sheet Iron

The paper describes a series of observations of magnetic quality in vai'ious specimens of sheet iron and iron wire. A principal object was to determine the amount of energy lost in consequence of magnetic hysteresis when the iron under examination was carried through cyclic magnetising processes between assigned limits of the magnetic induction B. For this purpose observations of the relation of the induction B to the magnetic force H were made, from which curves were drawn, and the area enclosed by the curves in cyclic magnetising processes was measured.

Research on the Magnetic Force of a Blood Pump Driven by Large Gap External Magnetic Field

2012 ◽  
Vol 271-272 ◽  
pp. 1636-1640
Author(s):  
Xiao Yan Tang ◽  
Zhong Yun ◽  
Chuang Xiang
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Magnetic Field Intensity ◽  
Current Theory ◽  
Calculation Model ◽  
Blood Pump ◽  
Single Turn ◽  
The Magnetic Field

The calculation model of the single turn rectangle current carrying coil was established. The theoretic formula for calculating the magnetic field intensity of any point in space was derived. For a pair of radial magnetizing permanent magnets, the formula for calculating the magnetic force of permanent magnet in the magnetic field was deduced based on the equivalent current theory of permanent magnet. According to the formula, the influencing factors and the changing rules for the magnetic force of permanent magnet can be seen directly: the current, the coil turns are proportional to its magnetic force, while the coupling distance is inversely proportional to its magnetic force.

scholarly journals Comparison of closed-form solutions to experimental magnetic force between two cylindrical magnets

2021 ◽  
pp. 141-146
Author(s):  
Sampart Cheedket ◽  
Chitnarong Sirisathitkul
Keyword(s):  
Magnetic Field ◽  
Closed Form ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Magnetic Levitation ◽  
Closed Form Solution ◽  
Vertical Tube ◽  
Form Solution ◽  
Closed Form Solutions ◽  
Set Up

The force between permanent magnets implemented in many engineering devices remains an intriguing problem in basic physics. The variation of magnetic force with the distance x between a pair of magnets cannot usually be approximated as x-4 because of the dipole nature and geometry of magnets. In this work, the force between two identical cylindrical magnets is accurately described by a closed-form solution. The analytical model assumes that the magnets are uniformly magnetized along their length. The calculation, based on the magnetic field exerted by one magnet on the other along the direction of their orientation, shows a reduction in the magnetic force with the distance x and a dependence on the size parameters of magnets. To verify the equation, the experiment was set up by placing two cylindrical neodymium iron boron type magnets in a vertical tube. The repulsive force between the identical upper and lower magnets of 2.5 cm in diameter and 7.5 cm in length was measured from the weight on the top of the upper magnet. The resulting separation between the magnets was recorded as x. The forces measured at x=0.004-0.037 m differ from the values calculated using the analytic solution by -0.55 % to -13.60 %. The calculation also gives rise to a practical remnant magnetic field of 1.206 T. When x is much large than the equation of force is approximated as a simple form proportional to 1/x-4. The finding can be directly used in magnetic levitation as well as applied in calculating magnetic fields and forces in other systems incorporating permanent magnets.

Numerical and experimental study of dynamics of two pendulums under a magnetic field

2019 ◽  
Vol 233 (4) ◽  
pp. 441-453 ◽  
Author(s):  
Krystian Polczyński ◽  
Adam Wijata ◽  
Jan Awrejcewicz ◽  
Grzegorz Wasilewski
Keyword(s):  
Magnetic Field ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Magnetic Interaction ◽  
Variable Magnetic Field ◽  
Phase Portraits ◽  
Bifurcation Diagrams ◽  
Regular Motion ◽  
Novel Model ◽  
Two Degree Of Freedom

In this article, a two-degree-of-freedom system consisting of two pendulums with magnets embedded in a variable magnetic field is investigated experimentally and numerically. Pivots of the pendulums are coupled by an elastic element. The magnetic interaction originates from permanent magnets, mounted at free ends of the pendulums and current-powered air coils underneath. A novel model for the magnetic force is proposed and verified experimentally. Nonlinear dynamics of the system is examined by means of time series, bifurcation diagrams, phase portraits, and Poincaré sections. Regions of chaotic and regular motion are predicted numerically and justified experimentally. Multiperiodic motion and coexisting solutions are detected, and pictures in basins of their attraction are reported, among other.

scholarly journals Rayleigh-Bénard Convection of Paramagnetic Liquid under a Magnetic Field from Permanent Magnets

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 341
Author(s):  
Kengo Wada ◽  
Masayuki Kaneda ◽  
Kazuhiko Suga
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Magnetic Induction ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Cell Pattern ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard ◽  
High Magnetic Induction

The convection control is important in terms of the heat transfer enhancement and improvement of the applied devices and resultant products. In this study, the convection control by a magnetic field from block permanent magnets is numerically investigated on the Rayleigh-Bénard convection of paramagnetic fluid. To enhance the magnetic force from the available permanent magnets, pairs of alternating-pole magnets are employed and aligned near the bottom heated wall. The lattice Boltzmann method is employed for the computation of the heat and fluid flow with the consideration of buoyancy and magnetothermal force on the working fluid. It is found that, since the magnetic force at the junction of pair magnets becomes strong remarkably and in the same direction as the gravity, descending convection flow is locally enhanced and the pair of symmetrical roll cells near the magnet junction becomes longitudinal. The local heat transfer corresponds to the affected roll cell pattern; locally enhanced at the magnet junctions and low heat transfer area is shifted aside the magnet outer edge. The averaged Nusselt number on the hot wall also increases proportionally to the magnetic induction but it is saturated at high magnetic induction. This suggests the roll cell pattern is no more largely affected at extremely-high magnetic induction.

scholarly journals XIX. Magnetic qualities of iron

1893 ◽  
Vol 184 ◽  
pp. 985-1039 ◽  
Keyword(s):  
Magnetic Hysteresis ◽  
Detailed Examination ◽  
Cyclic Process ◽  
Magnetic Cycle ◽  
Ballistic Method ◽  
Sheet Iron ◽  
Electrical Engineers ◽  
Magnetizing Force ◽  
Cyclic Variations ◽  
Energy Dissipated

Recent applications of electricity, and especially the extended use of transformers, have added particular interest to the study of cyclic magnetizing processes in iron. It has become a matter of consequence to investigate, in various specimens of metal, not only the amount of the energy dissipated by hysteresis in a magnetic cycle, hut the relative amounts under various degrees of magnetization and various intensities of magnetizing force. Other questions arise with regard to the dependence of this loss on the frequency of the cyclic process and on the manner in which it is performed. The experiments to be described in this paper deal mainly with the effects of cyclic variations of magnetizing force. They are intended to contribute some additions to existing data, to answer one or two specific questions, and to exemplify certain more or less novel methods of experimental inquiry. A section at the end of the paper relates to the molecular theory of magnetization, and its adequacy to explain some characteristic manifestations of magnetic hysteresis. Experiments on Rings, by the Ballistic Method. In a paper published eight years ago by one of us, experiments were described in which a piece of soft iron was carried through a numerous series of cycles of magneti­sation, of graded amplitude, with the object of determining the form taken by the curve of magnetization and magnetizing force during the process of reversal between any assigned limits, and of comparing the work spent in the process with the ampli­tude of the magnetization. A similar experiment was described for steel. Since then the importance of such information has been recognized by electrical engineers, and some experiments with a similar object have been made by Messrs, Evershed and Vignoles, and by Mr. C. P. Steinmetz. Notwithstanding, however, the increased interest which now attaches to the matter in consequence of its practical bearing, the available data are still meagre. By way of adding to them, we have made a detailed examination of some ten samples of wire and sheet iron, arranged in the form of rings to be operated on by the ballistic, method.

Measuring magnetic force and magnetic field of small permanent magnets

1990 ◽  
Vol 28 (2) ◽  
pp. 124-125 ◽  
Author(s):  
J. L. Sandoval ◽  
A. Porta ◽  
P. Segarra
Keyword(s):  
Magnetic Field ◽  
Magnetic Force ◽  
Permanent Magnets

scholarly journals Efficient Toughening of Short-Fiber Composites Using Weak Magnetic Fields

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2415
Author(s):  
Omri Goldberg ◽  
Israel Greenfeld ◽  
Hanoch Daniel Wagner
Keyword(s):  
Magnetic Field ◽  
Fracture Toughness ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
Glass Fibers ◽  
High Energy ◽  
Short Fiber ◽  
Local Concentration ◽  
Weak Magnetic Fields ◽  
Energy Dissipated

Short fibers may serve as toughening agents of composite materials because of the high energy dissipated during fracture, associated with numerous fiber pullouts. An ongoing challenge is to improve their toughness even further, by directing and concentrating fibers near highly stressed structural regions. Weak magnetic fields are utilized to increase the fracture toughness of an epoxy matrix reinforced by short magnetized glass fibers by directing and concentrating fibers near highly stressed structural regions. The orientation and local concentration of the fibers are controlled by the vector components of the magnetic field, and by the gradient in field intensity, respectively. Optimized fracture toughness was achieved by using two pairs of permanent magnets, combining enhanced concentration of fibers in the crack-tip vicinity with alignment of the fibers along the load direction. This optimized value was well above the reference fracture-toughness measured for composites with the same filler content in the absence of a magnetic field, as well as above the value achieved by exploiting unidirectional alignment, without fiber translation, using a solenoid. The method suggested in this study—localized reinforcement using magnetic translation of fillers through the formation of magnetic gradients—enables efficient and controllable improvement in the composite’s overall resistance to fracture, without the involvement of additional phases or material.

Study of MFM Application in Semiconductor Failure Analysis

2004 ◽  
Author(s):  
Way-Jam Chen ◽  
Lily Shiau ◽  
Ming-Ching Huang ◽  
Chia-Hsing Chao
Keyword(s):  
Magnetic Field ◽  
Failure Analysis ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Current Flow ◽  
Force Microscopy ◽  
The Magnetic Field ◽  
A Current

Abstract In this study we have investigated the magnetic field associated with a current flowing in a circuit using Magnetic Force Microscopy (MFM). The technique is able to identify the magnetic field associated with a current flow and has potential for failure analysis.

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.

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