Papers by Keyword: Magnetostriction

Abstract: The magnetostriction and magnetic properties of electrical steel are depended on the external stress. In this paper, a noncontact magneostriction measuring system using laser displacement meter with high resolution of 10 nm has been built. The grain-oriented electrical steel with dimensions 500 mm × 100 mm × 0.3 mm was measured between 20 MPa and-20 MPa. The magnetostriction and magnetic properties were highly sensitively to stress. A clear relationship between power loss and magnetostriction under stress was found, and the underlying mechanism has been discussed.

Abstract: Shear horizontal (SH) guided waves have been proved to be a viable method in the Non-Destructive Evaluation (NDE). Electromagnetic acoustic transducers (EMAT) can excite SH waves easily. By bonding the Fe-Co alloy to the test sample, the SH guided waves based on magnetostriction effect can be used to detect the flaw in nonferromagnetic material. The principle of exciting and receiving SH waves is introduced, and an experiment is carried out to validate the result.

Abstract: Introducing the principle, which the magnetostrictive displacement sensor is based on, and the gauging to small shifting is given in this paper. These sensor possess the peculiarities of high precision, long-life and easy to assemble. The gauging to small shifting belongs to the major characteristics test to artillery. On account of the faultiness existing testing means, this method is submitted to the characteristics test of artillery. Which magnetostrictive displacement sensor is applied to the shifting measure. By means of tests, the conclusion could be given that this method is easy to operate, automatic, high testing precision and widely used.

Abstract: The main features of the magnetic, magnetoelastic and record magnetoelectric properties of a HoAl₃(BO₃)₄ alumoborate single crystal have been studied experimentally and theoretically. For B||a we have observed a giant polarization ΔP_ba(B_a) ≈ –5240 µС/m² induced by field of 9 T at T = 5 K. We have calculated the magnetic characteristics of HoAl₃(BO₃)₄ in the framework of a crystal-field model. The parameters of the crystal-field in HoAl₃(BO₃)₄ have been determined. Good agreement of experimental and calculational magnetization curves M_c,^с(В) and the temperature dependences of magnetization M_с,^с(T) was achieved. For interpretation of magnetostriction in HoAl₃(BO₃)₄ the field and temperature dependences of the multipole moments have been calculated.

Abstract: The influence of the temperature, elastic tensile stresses and external magnetic field on the impedance of amorphous Co₇₅Fe₅Si₄B₁₆ ribbons was studied. It was observed that the character of the elastic tensile stresses influences the impedance and its changes in the external magnetic field are determined by a temperature of the ribbons. It was shown that changes of the stressimpedance character and magnetoimpedance temperature dependences were caused by a change in the sign of a magnetostriction constant with the temperature.

Abstract: An important source of transformer core vibration is magnetostriction of the thin silicon-steel lamination. In the power grid, direct current (DC) may form by solar magnetic storms and DC transmission. Transformer core supersaturation and harmonic increase in current caused by DC bias will intensify magnetostriction and produce additional transformer core vibration. In order to obtain transformer core vibration under DC bias, the magnetization curve and magnetostriction characteristics of thin silicon-steel lamination are measured. Then, this paper establishes a numerical magneto-mechanical strong coupling model including magnetostrictive effect under DC bias for three-phase three-column dry transformers. On the basis of the proposed model, and the measured magnetic characteristics of the thin silicon-steel lamination, transformer core vibration under DC bias and no-load condition has been calculated. In order to verify the proposed model, transformer core vibration under DC bias and no-load condition is studied experimentally. Numerical calculation results together with experimental results confirm the validity of the proposed method.

Abstract: Magnetorheological elastomers (MREs) are a class of smart composites whose mechanical properties can be obviously changed under different magnetic field. Only a few works study its magnetostrictive property, which describes the changes in dimensions of a material in its magnetization. Magnetostriction in the ferromagnetic particle is also called eigenstrain in MREs. It is modeled using the nonlinear function of the magnetization in this article. The eigenstrain due to the magnetostriction is incorporated in the structure of the MREs using a generalized Hookes Law. By means of initial strain, a finite element simulation is presented to describe the magnetostriction of MREs. The results show that the magnetostriction along the magnetic field depends on the magnetization and the volume fraction of particles. As an application, we will present numerical simulations for a magnetostriction and compare these results with measured data.

Abstract: The composition dependence of crystal structure, lattice parameter, micromorphology, Curie temperatures, magnetocrystalline anisotropy constant of Tb_0.29Dy_0.48Ho_0.23(Fe_1-XMn_X)_1.95 (x0.3) alloys were investigated by the experiment. X-ray diffraction patterns demonstrate the Tb_0.29Dy_0.48Ho_0.23(Fe_1-XMn_X)_1.95 (x0.3) alloys possess MgCu₂-type cubic Laves structure. The lattice parameter of Tb_0.29Dy_0.48Ho_0.23(Fe_1-XMn_x)_1.95 alloy increases with increasing of x value. The Curie temperature T_c decreases from 375°C for x=0 to 316 °C for x=0.05, 265°C for x=0.1. The magnetocrystalline anisotropy constant K₁ of Tb_0.29Dy_0.48Ho_0.23(Fe1_-xMn_x)_1.95 (x0.3) decreases slightly with the increasing of x value. The magnetostriction was examined under applied magnetic field H in the room temperature. The Tb_0.29Dy_0.48Ho_0.23(Fe_1-xMn_x)_1.95 (x0.2) alloys have the character of giant magnetostrictive in room temperature. With the increasing of Mn concentration, the magnetostrictive of Tb_0.29Dy_0.48Ho_0.23(Fe_1-xMn_x)_1.95 (x0.2) alloy decreased.

Abstract: Fe_81-xNi_xGa₁₉(with x ranging from 0-25 at.% Ni) ribbons were made by melt spinning method. We have studied the structural (phases, texturing, and lattice parameter), magnetic (saturation magnetization and saturation magnetostriction) properties of these ribbons. The main results are as follows: (i) For x≤10, all the ribbons are A₂ single phase; for x=15, the ribbon is of A₂+L1₂+DO₃+E2₁ phase; for x=20, the ribbon is of A₂+L1₂+DO₃+B₂ phase; for x=25, only A₂ and L1₂ phases exist. (ii) For x=5 and 15, an obvious (211) texture was detected, whereas other ribbons are (110) textured, no (100) texture was tested. (iii) (110) texture in our ribbons brought low saturation magnetic field (Hs) and high saturation magnetostrction (λs). (iv) E2₁ phase played a positive role in the magnetostricion of FeNiGa ribbons.

Abstract: Two series of Fe_81-xNi_xGa₁₉/Si (100) and Fe_81-yNi_yGa₁₉/glass films, where x or y = 0 26at.%Ni, were made by the magnetron sputtering method. We have performed three kinds of experiments on these films: the saturation magnetostriction (λ_S); [ii] the nanoindentation; and [iii] magnetic hysteresis-loop measurements. The main findings of this study are summarized below:[ λ_S reachesa local maximum, when x = 22 and [B] the Youngs modulus, E_f, of the Fe-Ni-Ga film deposited on a Si (100) substrate is larger than that (the same film) deposited on a glass substrate. We conclude thatthe Fe₅₉Ni₂₂Ga₁₉ film could beemployed in a low-field and low-costnano-magnetic switching device.