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题名 超导磁体导体的宏观力电行为和微观机理的研究
姓名 李瀛栩
院系 土木工程与力学学院
专业 固体力学
学位名称 工学博士
外文题名 Studying on the electro-mechanical behaviors and microscopic mechanism of superconducting cable conductors
第一导师姓名 高原文
关键词 超导电缆;性能退化;超导微观机理;临界态模型;电流输运;临界电流;电磁响应;上临界磁场
外文关键词 Superconducting cable;performance degradation;superconductivity;critical-state model;current transport;critical current;electromagnetic response;upper critical field
学科 工学
摘要 本论文围绕超导磁体导体的力—电—磁行为进行了理论建模和分析计算,旨在揭示超导电缆在运行环境下的力学变形及其对超导输运性能的影响,同时为优化电缆设计提供理论支撑和参考。本学位论文主要内容包括以下几个方面的研究内容:1)发展经典绳缆理论中的多层级方法,用以研究超导电缆在简单加载下的整体加载曲线和局部应变分布,同时运用有限元软件ABAQUS对理论模型的结果进行了验证和加强。2)将超导电缆中的多层级绞扭的股线等效为一螺旋形的弹性曲杆,周围股线对此股线的接触和压缩作用转化为这一等效股线的边界和加载条件。得到的超导电缆的输运电流电压特性曲线与试验结果吻合良好。3)对于受弯曲荷载的超导股线的电流输运进行了理论建模,得到了输运电流在股线内部的分布模式,并预测了实验测量中超导股线的临界电流退化。4)我们将Ginzburg-Landau-Abrikosov-Gor’kov理论拓展到处理A15型Nb3Sn中上临界磁场Hc2随着Sn含量的变化。5)引入了II型超导体的临界态模型,考虑了磁通线钉扎的各向异性,并用于分析各向异性双轴超导平板中的临界态发展情况。我们给出了在多种激励磁场边界条件和初始条件下,各向异性双轴平板中的磁场、电流和电场的分布特性。
外文摘要 We focus on the theoretical modeling and numerical analysis of the mechanical-electro-magnetic behaviors of CICC in superconducting magnets, aiming to discover the effect of the mechanical deformation on the superconducting transport performance, and to provide support/reference for the cabling design. The following presents the main content of this dissertation: 1) We develop an analytical model based on the hierarchical approach of classical wire rope theory, to calculate global displacement-load curve and local axial strain distribution. 2) The spring rod is taken as a more accurate description for strand helix, compared to rectilinear beam in most of previous models.The transport voltage-current curve at cable level is compared to the experimental one and found a good agreement. A certain extent of promotion for CICC performance is suggested to increase the subsequent twist pitch length and reduce the void fraction in a reasonable range. Besides increasing the twist angle with respect to the cable axis properly is helpful for reducing the degradation. 3) Based on the D Ciazynski and A Torre’s formulae, we propose an improved scheme, further revealing the intrinsic mechanism for TARSIS. Especially the obtained transverse transport map well characterizes the inter-filament transfer, showing clearly two pathways of the electric field and the filament twist dependence of the current. Meanwhile, the improved scheme is extended to describe the generalized transport properties, predicting V-I characteristic within a wide resistive range. The V-I curves illustrate the shift from typical power law behavior to less precise power law behavior with loading increasing. 4) We extend the Ginzburg-Landau-Abrikosov-Gor’kov (GLAG) theory to account for the variation of the upper critical field Hc2 with Sn content in A15-type Nb3Sn. Hc2 at the vicinity of the critical temperature Tc is related quantitatively to the electrical resistivity, specific heat capacity coefficient and Tc, with inclusion of the electron-phonon coupling correction, Pauli paramagnetic limiting and martensitic phase transformation of A15 lattices. 5) We introduce a critical-state model incorporating the anisotropy of flux-line pinning to analyze the critical states developing in an anisotropic biaxial superconducting slab exposed to a uniform perpendicular magnetic field and to two crossed in-plane magnetic fields which are applied successively. We find that an enhanced in-plane anisotropy mod...
研究领域 电磁固体力学与智能结构
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