Magnetic Anisotropy in Silicon Iron Alloys

Abstract In this article it is presented a study of the magnetic anisotropy of non -oriented and grain oriented Fe-Si strips with the surface area of 280 x 30 mm 2 . The measurements were performed with a unidirectional single strip tester on Fe -Si strips cut at 0, 15, 30, 45, 60, 75, 90 with the rolling direct ion. For the representation of the magnetic field strength at constant magnetic flu x density it was used a software program that interpolated the experimental results. It was determined the hard and the easy axis of the samples and the influence of the frequency on the anisotropy of the materials.The loss behaviour of these alloys was studied as a function of frequency in the range of 5 Hz to 200 Hz at a given magnetic polarization (J p ) of 1 T and using the concept of loss separation for the data analysis it was given a correlation between the different types of losses and the anisotropy axis

Correlation between Magnetic Properties and Chemical Composition of Non-Oriented Electrical Steels Cut through Different Technologies

Due to worldwide regulations on electric motor manufacturing, the energy efficiency of these devices has to be constantly improved. A solution may reside in the fact that high quality materials and adequate cutting technologies should be carefully chosen. The magnetic properties of non-oriented electrical steels are affected by the cutting methods, through induced plastic, and thermal stresses. There is also an important correlation between chemical composition and different magnetic properties. In this paper, we analyze different industrial grades of non-oriented electrical steels, used in electrical machines’ core manufacturing as M800-65A, M800-50A, M400-65A, M400-50A, M300-35A, and NO20. The influence of the cutting methods on the normal magnetization curve, total energy loss and its components, and relative magnetic permeability is investigated in alternating currents using a laboratory single sheet tester. The chemical composition and grain size influence are analyzed and correlated with the magnetic properties. Special attention is devoted to the influence of the increased cutting perimeter on the energy losses and to the way it relates to each chemical alloy constituent. The final decision in what concerns the choice of the proper magnetic material and the specific cutting technology for the motor magnetic cores is imposed by the desired efficiency class and the specific industrial applications

Effect of punching and water-jet cutting methods on magnetization curve and energy losses of non-oriented magnetic steel sheets

Strip samples of widths ranging between 5 mm and 30 mm were cut from different types of non-oriented magnetic steel sheets by means of guillotine shear cutting and water-jet technology and characterized from DC to 400 Hz. The measured magnetization curves and energy losses and their dependence on the strip width, that is, on the proportion of damaged to pristine sample cross-section, have been analyzed and modeled. While confirming an expected lighter material deterioration engendered by water-jet cutting, the analysis of the results remarkably shows that the evolution of the normal magnetization curve and the quasi-static magnetic losses with the width of the cut strip follows a hyperbolic law. This novel finding permits one to predict, using minimum pre-emptive information, the evolution of normal magnetization curve and hysteresis loss from indefinitely wide to narrow fully degraded strip. The highly strain-hardened region is, in this way, estimated to propagate from the strip edge by about 2.1 mm and 1.6 mm in the punched and water-jet cut samples, respectively. The dynamic loss behavior is assessed by analysis of the excess loss component, in accordance with the statistical theory of losses. A small to moderate increase of the dynamic loss (i.e. of the excess loss) with decreasing strip width is found, following to some extent the behavior of the quasi-static loss

Effect of punching and water-jet cutting methods on magnetization curve and energy losses of non-oriented magnetic steel sheets

Strip samples of widths ranging between 5 mm and 30 mm were cut from different types of non-oriented magnetic steel sheets by means of guillotine shear cutting and water-jet technology and characterized from DC to 400 Hz. The measured magnetization curves and energy losses and their dependence on the strip width, that is, on the proportion of damaged to pristine sample cross-section, have been analyzed and modeled. While confirming an expected lighter material deterioration engendered by water-jet cutting, the analysis of the results remarkably shows that the evolution of the normal magnetization curve and the quasi-static magnetic losses with the width of the cut strip follows a hyperbolic law. This novel finding permits one to predict, using minimum pre-emptive information, the evolution of normal magnetization curve and hysteresis loss from indefinitely wide to narrow fully degraded strip. The highly strain-hardened region is, in this way, estimated to propagate from the strip edge by about 2.1 mm and 1.6 mm in the punched and water-jet cut samples, respectively. The dynamic loss behavior is assessed by analysis of the excess loss component, in accordance with the statistical theory of losses. A small to moderate increase of the dynamic loss (i.e. of the excess loss) with decreasing strip width is found, following to some extent the behavior of the quasi-static loss

Effect of mechanical cutting on the energy loss of laser-scribed grain-oriented alloys

We investigate the effect of mechanical cutting on the magnetic properties of high permeability grain-oriented (HGO) laser-scribed Fe-Si sheets. Measurements have been performed on strips of different widths (5 to 60 mm) cut from 0.27 mm thick sheets. Normal magnetization curve and energy loss have been determined by means of a digitally controlled single strip tester from 1 Hz to 1 kHz at peak magnetic polarization values Jp = 1000 mT and 1700 mT. The results fit into a simple phenomenological model regarding the dependence of magnetization curve and energy loss on the strip width, in substantial continuity with the approach originally developed for non-oriented electrical steels. The hysteresis Wh and excess Wexc loss components are shown to depend on the strip width according to a hyperbolic law, with a limiting fully hardened strip predicted to occur for widths around 3.5 mm. It is then consistently observed that the mechanical cutting of standard 30 mm wide HGO Epstein strips is conducive to an increase of the energy loss at 50 Hz and 1.7 T of the order of 13 %

Influence of mechanical and water-jet cutting on the dynamic magnetic properties of NO Fe-Si steels

Magnetization curve and energy losses have been analyzed in non-oriented (NO) Fe-Si alloys with variable thickness (0.20 mm–0.35 mm), cut at widths ranging between 5 mm and 60 mm, in order to assess the impact of cutting, either done by punching or water-jet techniques. Measurements were performed by means of a digitally controlled single strip tester, from dc up to 1.5 kHz, at peak polarization values Jp = 1.0 T and 1.5 T. The evolution of the magnetization curve and the structure-dependent hysteresis Wh and excess Wexc loss components have been assessed as a function of the strip width using a simple phenomenological model, by which the extension of the damaged area at the edges of the cut sheets is estimated. Such a model assumes a hyperbolic dependence of the measured polarization on the cut strip width

Self-Organizing Equilibrium Patterns of Multiple Permanent Magnets Floating Freely under the Action of a Central Attractive Magnetic Force

The present communication revisits the almost century-and-a-half-old problem of some identical small magnets floating freely on the water’s surface under the action of a superimposing magnetic field created by a stronger magnet placed above them. Originally introduced and performed by Alfred Marshall Mayer and reported in a series of articles starting from 1878 onward, the proposed experiments were intended to provide a model (theoretical and educational) for the building block of matter that, at a microscopic level, is the atom. The self-organizing patterns formed by the repelling small magnets under the influence of a single attractive central force are presented in a slightly different reenactment of the original experiments. Although the set-up is characterized by an axially symmetric magnetostatic structure, and the floated magnets are all identical, the resulting equilibrium patterns are not necessarily symmetrical, as one would expect. To the authors’ best knowledge, the present communication proposes for the first time a quantitative approach to that extremely complex conceptual problem by providing a methodology for computing the equilibrium point coordinates in the case of n = 1…20 floating magnets, as proposed by the original A.M. Mayer experiments. A good agreement between the experiments and computed data was demonstrated for n = 2…15 (1st variant), but it was less accurate while still preserving the experimental set-up configurations for n = 15 (2nd variant)…20. Finally, this study draws the conclusions from the performed experiments and their corresponding computer simulations, identifies some open issues, and outlines possible solutions to address them, as well as future developments concerning the subject in general

Additive Manufactured Magnesium-Based Scaffolds for Tissue Engineering

Additive manufacturing (AM) is an important technology that led to a high evolution in the manufacture of personalized implants adapted to the anatomical requirements of patients. Due to a worldwide graft shortage, synthetic scaffolds must be developed. Regarding this aspect, biodegradable materials such as magnesium and its alloys are a possible solution because the second surgery for implant removal is eliminated. Magnesium (Mg) exhibits mechanical properties, which are similar to human bone, biodegradability in human fluids, high biocompatibility, and increased ability to stimulate new bone formation. A current research trend consists of Mg-based scaffold design and manufacture using AM technologies. This review presents the importance of biodegradable implants in treating bone defects, the most used AM methods to produce Mg scaffolds based on powder metallurgy, AM-manufactured implants properties, and in vitro and in vivo analysis. Scaffold properties such as biodegradation, densification, mechanical properties, microstructure, and biocompatibility are presented with examples extracted from the recent literature. The challenges for AM-produced Mg implants by taking into account the available literature are also discussed

Mechanical and Computational Fluid Dynamic Models for Magnesium-Based Implants

Today, mechanical properties and fluid flow dynamic analysis are considered to be two of the most important steps in implant design for bone tissue engineering. The mechanical behavior is characterized by Young’s modulus, which must have a value close to that of the human bone, while from the fluid dynamics point of view, the implant permeability and wall shear stress are two parameters directly linked to cell growth, adhesion, and proliferation. In this study, we proposed two simple geometries with a three-dimensional pore network dedicated to a manufacturing route based on a titanium wire waving procedure used as an intermediary step for Mg-based implant fabrication. Implant deformation under different static loads, von Mises stresses, and safety factors were investigated using finite element analysis. The implant permeability was computed based on Darcy’s law following computational fluid dynamic simulations and, based on the pressure drop, was numerically estimated. It was concluded that both models exhibited a permeability close to the human trabecular bone and reduced wall shear stresses within the biological range. As a general finding, the proposed geometries could be useful in orthopedics for bone defect treatment based on numerical analyses because they mimic the trabecular bone properties