多层磁场旋转式电涡流惯容阻尼器力学性能研究

为提高电涡流阻尼器输出的阻尼力,提出一种多层磁场旋转式电涡流惯容阻尼器(multilayer magnetic field rotary eddy current inertial damper,MMF-RECID),对其力学性能进行试验研究和有限元仿真。首先,介绍MMF-RECID的构造,建立MMF-RECID轴向力计算公式;然后,详细介绍了MMF-RECID试验样机,并考察在轴向反复荷载作用下MMF-RECID的惯容效应和耗能滞回性能,对MMF-RECID的轴向力组成进行分析,通过ANSOFT Maxwell软件对MMF-RECID的电涡流阻尼进行三维瞬态数值仿真,最后对一个设置MMF-RECID单自由度结构的减震效果进行分析。结果表明:MMF-RECID的滚珠丝杠传动系统实现了惯性质量和电涡流阻尼力的双重增效,多层磁场输出的电涡流阻尼力符合磁场线性叠加的规律,滞回曲线稳定、饱满;加载频率会改变MMF-RECID滞回曲线主轴方向的斜率以及轴向力的组成比例;ANSOFT Maxwell三维瞬态仿真结果与试验结果具有一致性;MMF-RECID具有良好的减震效果,且耗能密度高,具有工程应用可行性。

基于多层磁场的大长段电缆护套感应电压精确计算方法

电缆分段段长的大小主要取决于金属护套感应电压的大小,最大值不能超过国标300 V,因此金属护套感应电压的精确计算是确定段长的关键。基于电磁场理论,建立三相电缆空间磁场分布的数学模型,并计及电缆的结构参数,计算空间某一位置的金属护套感应电压。使用仿真软件进行验证,并与现有简化公式法计算结果对比表明,考虑电缆结构参数的电磁场求解法的计算结果与仿真结果更加接近,尤其是对于线径较小容量较低的电缆,为大长段电缆段长的选择提供理论指导作用。

铝转子单边盘式感应电机的新型等效电路

铝转子单边盘式感应电机气隙较大,主要参数随半径变化,用传统电机分析法会造成较大误差,且无法准确描述铝转子中集肤效应的影响.采用一种新的电磁模型,利用分环计算和多层行波磁场模型有效解决了该电机存在的特殊问题,提高了模型精度.通过磁场分布计算得到电机的T型等效电路.分析了等效电路中电感和电阻参数.制作样机并通过空载试验和短路试验测定其T型等效电路参数,试验结果与计算结果误差较小,证明该方法能准确估算铝转子单边盘式感应电机的主要参数.计算电机电磁转矩随转差率变化的情况,高转差率下的实验转矩输出值与计算值接近.

Critical Behavior of the Gaussian Model with Periodic Interactions on Diamond—Type Hierarchical Lattices in External Magnetic Fields

The Gaussian spin model with periodic interactions on the diamond-type hierarchical lattices is constructed by generalizing that with uniform interactions on translationally invariant lattices according to a class of substitution sequences. The Gaussian distribution constants and imposed external magnetic fields are also periodic depending on the periodic characteristic of the interaction bonds. The critical behaviors of this generalized Gaussian model in external magnetic fields are studied by the exact renormalization-group approach and spin rescaling method. The critical points and all the critical exponents are obtained. The critical behaviors are found to be determined by the Gaussian distribution constants and the fractal dimensions of the lattices. When all the Gaussian distribution constants are the same, the dependence of the critical exponents on the dimensions of the lattices is the same as that of the Gaussian model with uniform interactions on translationally invariant lattices.

Vector imaging of electric field-induced reversible magnetization reversal in exchange-biased multiferroic heterostructures

Exchange bias between ferromagnetic and antiferromagnetic layers has been widely utilized in spintronic devices.Controlling the exchange bias in magnetic multilayers by an electric field(E-field)has been proposed as a low-power solution for manipulating the macroscopic properties such as exchange bias fields and magnetization values,while how the magnetic domains respond to the E-fields has rarely been reported in an exchange-biased system.Here,we realize the vector imaging of reversible electrical modulation of magnetization reversal in exchange-biased CoFeB/IrMn/PMN-PT(011)multiferroic heterostructures,utilizing in-situ quantitative magneto-optical Kerr effect(MOKE)microscopy.Under the electrical control,magnetic domains at-80 Oe rotate reversibly between around 160°and 80°-120°,whose transverse components reverse from 225°to 45°correspondingly.Moreover,pixel-by-pixel comparisons are conducted to further imply the reversible magnetization reversal by E-fields.Efield-induced reversible magnetization reversal is also demonstrated without applying external magnetic fields.Vector imaging of electrical manipulation of exchange bias is of great significance in understanding the magnetoelectric effect and the development of next-generation spintronic devices.