Wiedemann effect of Fe-Ga based magnetostrictive wires

（Fes3Ga17）98Cr2 wires each with a diameter of 0.7 mm are prepared by hot swaging and warm drawing from the casting rods directly, because the ductility of Fes3Ga17alloy is improved by adding Cr element. The Wiedemann twists and dependences on magnetostrictions of Fe83Ga17 and （Fe83Ga17）98Cr2 wires are investigated. The largest observed Wiedemann twists of 245 s.cm-1 and 182 s.cm-1 are detected in the annealed Fes3Ga17 and （Fe83Ga17）98Cr2 wires, respectively. The magnetostrictions of the annealed Fes3Ga17 and （Fes3Ga17）98Cr2 wires are 160 ppm and 107 ppm, respectively. The maximum of the Wiedemann twist increases with magnetostriction increasing. However the magnetostriction is just one important factor that affects the Wiedemann effect of alloy wire, and the relationship between magnetostriction and Wiedemann effect is a complex function rather than a simple function.

Frequency dependence of the magnetoelectric effect in a magnetostrictive-piezoelectric heterostructure

The frequency dependence of the magnetoelectric effect in a magnetostrictive-piezoelectric heterostructure is theoretically studied by solving combined magnetic, elastic, and electric equations with boundary conditions. Both the mechanical coupling coefficient and the losses of the magnetostrictive and piezoelectric phases are taken into account. The numerical result indicates that the magnetoelectric coefficient and the resonance frequency are determined by the mechanical coupling coefficient, losses, and geometric parameters. Moreover, at the electromechanical resonance frequency, the module of the magnetoelectric coefficient is mostly contributed by the imaginary part. The relationship between the real and the imaginary parts of the magnetoelectric coefficient fit well to the Cole–Cole circle. The magnetostrictive-piezoelectric heterostructure has a great potential application as miniature and no-secondary coil solid-state transformers.

Preparation and Compressive Stress Effect of Polymer Matrix RE-Fe Giant Magnetostrictive Composite

Polymer matrix RE-Fe giant magnetostrictire composite （GMPC） was prepared using bonding and magnetic field forming technique, and magnetostriction of samples was measured for different compressive stress. The experimental results show thai there is certain compressive effect in GMPC. And the influence of compressive stress on magnetostriction of sample was investigated. It offers essential reference for application and device design of GMPC.

INFLUENCE OF HEAT TREATMENT ON THE COMPRESSIVE STRESS EFFECT OF MAGNETOSTRICTION OF <112> AXIAL ALIGNED Tb-Dy-Fe ALLOYS

The magnetostrictive properties of <112> axial aligned Tb0.3Dy0.7(Fe1-xMx)1.95(M=Mn, Al, x=0～ 0.15) alloys prepared by directional solidification are reported. The influence of heat treatment on microstructure and the compressive stress effect of magnetostriction is discussed.

Giant Volume Magnetostriction Caused by Itinerant Electron Metamagnetic Transition and Pronounced Invar Effects in La(Fe_xSi_(1-x))_(13) Compounds

A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below TC, closely correlated with the negative mode-mode coupling among spin fluctuations.

Influence of Magnetic Heat Treatment and Compressive Stress on Jump Effect of Magnetostriction of Tb_(0.3)Dy_(0.7)Fe_(1.95) Alloy

The 〈 110 〉 -oriented TTb0.3Dy0.7Fe1.95 polycrystalline alloy was magnetically annealed, and its influence on jump effect of magnetostriction was investigated. In the vacuum superconductive high magnetic field equipment, 〈 110 〉 -oriented Tb0.3Dy0.7Fe1.95 polycrystalline alloy of the directional solidification was annealed at 623 and 723 K for 5 min under the magnetic field vertical to specimen axis. It is found that magnetic annealing can enhance the jump effect under compressive stress, and increase the saturated magnetostriction coefficient λs, the λs of the magnetic annealing specimens at 623 K under 8.1 MPa is attained to 1950 × 10^-6, Magnetic annealing increases the maximum of dynamic magnetostriction coefficient, d33^max, as well as the magnetic field for d33^max under 8.1 MPa.

Coupling of the Magnetostriction and Hall Effect in the Porous Magnetorheological Composite

The first part of this paper is presents a method for producing the composite which shows ferromagnetic, highly-elastic and electrically-conducting properties. This composite consists of ferromagnetic particles of the size 0.15-0.25 mm made of the chemically pure iron. The mentioned particles were dispersed in the elastic porous silicone the matrix with pores of the size 0.15-0.25 mm. Colloidal graphite particles of the size not exceeding 0.5 μm were added to the matrix to increase electrical conductivity. The production method consist in mixing particles of iron, graphite and sodium chloride with non-polymerized silicone and rinsing salt particles by water after the matrix polymerization. In its second part the paper provides a description of the measurement system for longitudinal magnetostriction and the Hall voltage. The magnetic field with the induction of ± 8 T produced by the Bitter type magnet was applied to the composite samples. The supplying voltage was applied to these samples and the Hall voltage was measured at the electrodes glued to them. The longitudinal magnetostriction was measured by means of the capacitor with a variable capacity placed at the upper surface of these samples. The linear magnetostriction exceeding ± 6 % and the Hall voltage reaching ± 5.5 nV were detected by the conducted measurements. Both the longitudinal magnetostriction and the Hall voltage show nonlinear changes and hysteresis lopes during the magnetic field application and the supplying current flow. The coupling of these changes and other regularities observed in the investigated composites and especially their non-linearity and hysteresis, are discussed in the final part of the paper.

Coupling effects between elastic and electromagnetic fields from the perspective of conservation of energy

Coupling effects among different physical fields reflect the conversion of energies from one field into another substantially.For simple physical processes,their governing or constitutive equations all satisfy the law of conservation of energy(LCE).Then,an analysis is extended to the coupling effects.First,for the linear direct and converse piezoelectric and piezomagnetic effects,their constitutive equations guarantee that the total energy is conserved during the process of energy conversion between the elastic and electromagnetic fields.However,the energies are converted via the work terms,(βijkEi),kvj and(γijkHi),kvj,rather than via the energy terms,βijkEiejk andγijkHiejk.Second,for the generalized Villari effects,the electromagnetic energy can be treated as an extra contribution to the generalized elastic energy.Third,for electrostriction and magnetostriction,both effects are induced by the Maxwell stress.Moreover,their energies are purely electromagnetic and thus both have no converse effects.During these processes,the energies can be converted in three different ways,i.e.,via the non-potential forces,via the cross-dependence of the energy terms,and directly via the electromagnetic interactions of ions and electrons.In the end,the general coupling processes which involve elastic,electromagnetic fields and diffusion are also analyzed.The advantages of using this energy formulation are that it facilitates discussion of the conversion of energies and provides better physical insights into the mechanisms of these coupling effects.

2 GeV Electron Beam Irradiation Effects in Advanced Metallic Glasses

Six amorphous alloys (Alloy 1: Fe56Co24Nb4B13Si2Cu1, Alloy 2: Fe68.5Co5Nb3Cu1Si15.5B7, Alloy 3: Fe75.3Ni0.8Cr0.9Si8.7B14.3, Alloy 4: Fe56Co24Cr10Nb4B3Si1Cu2, Alloy 5: Fe72.9Nb3Cu1Si16.2B6.9, Alloy 6: Fe83.3Si8.6Nb5.5B1.4Cu1.2) were selected in terms of their composition and magnetostriction constants and uniformly irradiated in a high radiation environment in Hall A of the Thomas Jefferson National Accelerator Facility. The 2 GeV electron beam irradiation-induced effects were characterized by Mӧssbauer spectroscopy. The microstructural changes were related to the evolution of the hyperfine magnetic field distributions and isomer shifts. In particular, the occurrence of stress centers in the amorphous materials was evidenced.

基于Armstrong能量模型的非线性动态维拉里磁滞行为建模与验证

磁致伸缩材料工作在应力激励条件下的输出特性在很大程度上取决于偏置条件(预应力、偏置磁场)和激励频率。为指导磁致伸缩材料在动态应力驱动下的应用,需要建立一个能够适应各种操作条件的动态磁滞模型。该文结合Armstrong能量模型和J-A磁滞模型,建立了磁致伸缩材料的静态维拉里磁滞模型,通过引入频率相关时间常数的一阶微分方程将静态模型拓展为考虑动态损耗的动态非线性维拉里磁滞模型。利用粒子群遗传优化算法通过三个递进步骤提取模型参数。实验数据与模型计算数据的对比结果表明,该模型不仅能够充分描述预应力和偏置磁场对准静态维拉里效应的影响,而且能够反映在不同频率动态应力下磁通密度-应力(B-σ)动态小环和主环的变化趋势,该模型可为磁致伸缩材料器件在应力条件下的应用提供理论指导。

基于L型铁钴的三维力触觉传感器设计及输出特性

该文提出了一种基于L型铁钴丝的三维力触觉传感器,利用磁致伸缩材料铁钴合金设计制作了三维力触觉传感单元,并测试了该结构的输出特性。基于电磁原理、逆磁致伸缩效应和欧拉伯努利动力学原理,推导了输出电压方程。搭建触觉传感单元实验平台,对传感器进行法向和切向标定,设计的传感器法向测力范围为0~13 N,切向测力范围为0~6 N,输出特性具有良好的线性关系。其中,0~8 N法向力范围内灵敏度约为23.997 mV/N,9~13 N法向力范围内灵敏度约为17.537 mV/N;0~4 N切向力范围内灵敏度约为11.599 mV/N,5~6 N切向力范围内灵敏度约为6.281mV/N。在4Hz频率、2N法向力条件下,该传感器动态响应的输出电压幅值变化范围为46.5~49.8mV,与静态力输出电压幅值的相对误差低于5%,响应时间和恢复时间分别为25 ms和29ms,表明该传感器具有良好的动态特性。分别采用广义逆矩阵和BP神经网络对传感器测得的三维力进行解耦,其中,BP神经网络解耦方法平均误差仅有2.90%,可有效提高测量精度。该传感器体积小、输出线性度好,可同时实现静态力和动态力的测量,在智能机器人等领域具有良好的应用前景。

磁弹性生物传感器在食品检测中的研究进展

对引起食品安全问题的主要污染物,如食源性病原体、重金属残留、农药/兽药残留等进行快速而有效的检测是减少食品安全事故发生的重要监控点,高效、灵敏和准确的检测方法对食品检测领域意义重大。近年来,磁弹性生物传感器由于其无毒、低成本、便携、高灵敏度、高准确性和特异性以及可与无线网络连接等特点逐渐成为研究热点。该文主要介绍磁弹性生物传感器的工作原理及其在食品检测应用中的研究进展,以期为食品检测领域提供新思路。

光纤磁场传感器研究现状及发展趋势

磁测量在矿产勘探、工业制造和国防等领域有广泛应用,因此,对促进科学、技术和社会发展具有重要的意义。目前,电学磁场传感器存在绝缘结构复杂、成本高、抗干扰能力差、难以数字化等缺点。相比之下,光纤磁场传感器具有绝缘性好、结构小巧、可数字化,具备强大的抗干扰能力以及高度可复用性。因此,光纤磁场传感器为解决这些问题提供了高度可行的方法。详细论述了基于磁致伸缩效应、法拉第效应和磁流体材料的光纤磁场传感器的工作原理、研究现状及存在的挑战,然后展望了光纤磁场传感器的未来发展方向和前景。

干式铁芯电抗器振动特性数值模拟及试验研究

振动是影响干式铁芯电抗器运行状态的关键因素之一。在考虑铁芯夹件、垫块等结构件的影响下,采用有限元法实现了10 kV干式铁芯电抗器的3维瞬态电磁-结构多物理场仿真分析,研究了电抗器在磁致伸缩力、麦克斯韦力与洛伦兹力3者共同作用下的振动位移及速度分布特性。仿真结果表明,正常运行状态下,干式铁芯电抗器铁芯夹件的振动位移及速度显著大于其他部位,尤其是用于固定绕组的穿心螺杆。其次,结合干式铁芯电抗器模态仿真分析,获得了其模态特性及固有频率,并进一步分析了其振动机理。最后,采用多普勒激光测振仪测量了某10 kV干式铁芯电抗器的振动特性。试验结果表明,干式铁芯电抗器的振动频率以100 Hz及其倍频为主,其中300 Hz的振动响应最显著,其与其固有频率较接近,存在一定的共振风险。同时,试验结果与仿真结果一致性较好,验证了该文所述仿真分析方法的正确性和有效性。

Large,low-field and reversible magnetostrictive effect in MnCoSi-based metamagnet at room temperature

TiNiSi-type MnCoSi-based alloys show large magnetostriction during the magnetic-field-induced metamagnetic transition.However,the high critical field required to drive the transition directly hinders their potential applications.In this work,we systematically investigate the tricritical behavior and magnetostrictive effect in substituted MnCoSi alloys.Replacing Si with Sb or In,Co with Fe or Cu,and Mn with Co,which can simultaneously reduce the critical field and the temperature of tricritical point,are explored.Among the substituted MnCoSi alloys,Mn_(0.983)Co_(1.017)Si displays a temperature of a tricritical point of 250 K and a room-temperature critical field of 0.60 T,which is the lowest up to now.Profited from these optimizations,a large reversible magnetostrictive effect under low field is successfully realized at room temperature.In a field of 1 T,the magnetostriction of Mn_(0.983)Co_(1.017)Si alloy is close to 1000 ppm.Besides,a strong relation between critical field and valence electron concentration is revealed in the transition-metal-substituted MnCoSi alloys.Our work greatly enhances the low-field magnetostrictive performance of MnCoSi-based alloys and make them be of interest in potential applications.

Magnonic frequency combs based on the resonantly enhanced magnetostrictive effect

A magnonic counterpart to optical frequency combs is vital for high-precision magnonic frequency metrology and spectroscopy.Here,we present an efficient mechanism for the generation of robust magnonic frequency combs in a yttrium iron garnet(YIG)sphere via magnetostrictive effects.We show that magnonic and vibrational dynamics in the ferrimagnetic sphere can be substantively modified in the presence of magnetostrictive effects,which results in degenerate and non-degenerate magnonic four-wave mixing and frequency conversion.Particularly,resonantly enhanced magnetostrictive effects can induce phonon laser action above a threshold,which leads to significant magnonic nonlinearity and enables a potentially practical scheme for the generation of robust magnonic frequency combs.Numerical calculations of both magnonic and phononic dynamics show excellent agreement with this theory.These results deepen our understanding of magnetostrictive interaction,open a novel and efficient pathway to realize magnonic frequency conversion and mixing in a magnonic device,and provide a sensitive tool for precision measurement.

光学电流互感器的研究现状及发展趋势

传统的电磁感应式电流互感器存在结构庞大复杂、响应速度慢、安全水平低等问题,因而学者们将各种传感技术与光纤相结合,探索在未来能够成为电力系统主要应用的光学电流互感器。随着光电子技术的成熟发展,光学电流互感器应运而生。它具有高灵敏度、高集成度、高稳定性和在复杂环境下工作的能力等突出优点。针对光学电流互感器按照原理不同进行分类,对全光纤电流互感器、基于磁致伸缩效应的电流互感器、基于磁光效应的电流互感器、基于热效应的电流互感器的原理、结构、制造技术和信号处理的研究现状进行评述,并对其未来发展趋势进行预测。

基于Android移动终端的双通道磁弹性免疫传感装置

传统检测仪器昂贵且上手难度大,不仅提高了微机电检测系统的操作门槛,而且极大地限制了其使用场合和适用人群,磁弹性传感器正是面临这种难题的微机电系统之一。为了解决这一问题,应用STM32F407作为硬件系统的主控芯片,联合Android移动开发技术设计了一种基于Android移动终端的双通道磁弹性免疫传感装置。用Metglas合金2826制成的同参数磁弹性传感器对D-二聚体进行分析,实验结果表明,基于Android移动终端的免疫传感设备不仅可以得到与传统检测仪器———矢量网络分析仪3656A相当的结果。其能够在0.25μg/mL到2.5μg/mL对D-二聚体进行检测,检测限可达45 ng/mL,并且具有低成本、低功耗、便携和对用户友好的优势,有发展成为新一代家庭健康检测设备的潜力。

基于锁模激光器的FBG电流传感器高速解调系统

智能电网可靠、安全、经济、高效的发展目标,对电流参数的检测速率提出了更高的需求。本文开展了锁模激光器对基于磁致伸缩效应的光纤布拉格光栅(fiber Bragg grating, FBG)电流传感器复用实现高速解调的实验研究,首次将时间拉伸-色散傅里叶变换(time-stretch dispersive Fourier transformation, TS-DFT)技术与光纤电流传感技术进行了结合。固定于磁致伸缩材料表面的FBG能够感知通电螺线管产生的磁场所引发的材料应变。TS-DFT技术可将应力引起的FBG波长偏移映射为时域上反射脉冲的时延偏移实现高速解调。在0~4.5 A电流范围内对2个传感FBG的波长复用进行监测,系统的解调速率高达69.6 MHz,该技术在电流或磁场传感领域有广阔的应用前景。

磁致伸缩式扭转超声波位移传感器的研究与设计

介绍磁致伸缩式扭转超声波位移传感器的工作原理及设计机制 ,该传感器利用磁致伸缩的Wiedeman效应发射扭转波 ,利用磁致伸缩逆效应接收回波信号 ,根据发射脉冲与回波信号的时间差计算活动磁铁的位置。由于磁致伸缩材料和扭转波传播的特性 ,以及测量电路对于精确测时功能的实现 ,使得该传感器同时具有精度高、成本低、寿命长和安装简便 ,适用范围宽等优点。