Computations and measurements of the magnetic polarizability tensor characterisation of highly conducting and magnetic objects
Computations and measurements of the magnetic polarizability tensor characterisation of highly conducting and magnetic objects
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DOI：
10.1108/ec-11-2022-0688
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发表时间：
2023-08
影响因子：
1.6
通讯作者：
J. Elgy;P. Ledger;J. L. Davidson;T. Özdeğer;A. Peyton
中科院分区：
文献类型：
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作者：
J. Elgy;P. Ledger;J. L. Davidson;T. Özdeğer;A. Peyton
利用复对称二阶磁极化率张量（MPT）识别高导电物体（也可能是高磁性物体）的能力对于金属检测应用是重要的，包括在安全检查中区分威胁和非威胁物体、识别未爆炸的杀伤人员地雷和弹药以及在废料分类中识别具有高商业价值的金属。许多日常非威胁物品具有大的导电性和磁行为，对于足够弱的场和感兴趣的频率，可以通过高的相对磁导率来建模。本文的目的是讨论上述idea.Design/methodology/approachThe的MPT的日常非威胁的高传导磁性物体在很宽的频率范围内的数值模拟是具有挑战性的，由于所产生的薄集肤深度。作者通过采用基于四面体单元的非结构化网格的高阶边缘有限元离散化来解决这一问题，并添加了薄层棱柱形单元。此外，计算机辅助设计（CAD）的非威胁和威胁对象的几何模型往往是不可用的，相反，作者提取的几何特征的对象从imaging procedure.FindingsThe作者获得准确的数值MPT characterisations是在接近现实的物理对象的实验测量。不确定性的评估显示几何和材料参数的不确定性对计算结果的影响。独创性/valueThe作者提出了新的计算和测量MPT表征的磁性材料制成的现实物体。一种新的评估不确定性的数值预测MPT表征不确定的几何形状和材料参数。
PurposeThe ability to characterise highly conducting objects, that may also be highly magnetic, by the complex symmetric rank–2 magnetic polarizability tensor (MPT) is important for metal detection applications including discriminating between threat and non-threat objects in security screening, identifying unexploded anti-personnel landmines and ordnance and identifying metals of high commercial value in scrap sorting. Many everyday non-threat items have both a large electrical conductivity and a magnetic behaviour, which, for sufficiently weak fields and the frequencies of interest, can be modelled by a high relative magnetic permeability. This paper aims to discuss the aforementioned idea.Design/methodology/approachThe numerical simulation of the MPT for everyday non-threat highly conducting magnetic objects over a broad range of frequencies is challenging due to the resulting thin skin depths. The authors address this by employing higher order edge finite element discretisations based on unstructured meshes of tetrahedral elements with the addition of thin layers of prismatic elements. Furthermore, computer aided design (CAD) geometrical models of the non-threat and threat object are often not available and, instead, the authors extract the geometrical features of an object from an imaging procedure.FindingsThe authors obtain accurate numerical MPT characterisations that are in close agreement with experimental measurements for realistic physical objects. The assessment of uncertainty shows the impact of geometrical and material parameter uncertainties on the computational results.Originality/valueThe authors present novel computations and measurements of MPT characterisations of realistic objects made of magnetic materials. A novel assessment of uncertainty in the numerical predictions of MPT characterisations for uncertain geometry and material parameters is included.