A 3D Model on the Electromechanical Behavior of a Multifilament Twisted Nb3Sn Superconducting Strand
A 3D Model on the Electromechanical Behavior of a Multifilament Twisted Nb3Sn Superconducting Strand
复制标题
多丝扭曲 Nb3Sn 超导绞线机电行为的 3D 模型
DOI：
10.1007/s10948-015-3080-z
复制
发表时间：
2015-09-01
影响因子：
1.8
通讯作者：
Gao, Yuanwen
中科院分区：
文献类型：
--
作者：
Ta, Wurui;Li, Yingxu;Gao, Yuanwen
目前，Nb3Sn线等常规低温超导体已广泛应用于高能物理、核物理以及磁共振成像系统中。本文建立了三维有限元模型，考虑了复杂的超导纤维束结构和金属矩阵单元，研究了Nb3Sn线在拉伸和弯曲载荷作用下的电磁行为。纤维束和金属基体的力学本构关系分别用弹性和弹塑性轴向应力-应变曲线描述。金属基元的伏安特性符合欧姆定律，超导灯丝的伏安特性符合幂函数关系。通过ITER Nb3Sn线的标度律，模拟了其应力应变状态，并在电磁模型中实现。我们发现铜和绞合丝的塑性导致了不均匀应变分布的增强，而不是未加绞合丝的钢绞线的应变分布。我们还讨论了拉伸和弯曲载荷下的电流/场分布、临界电流退化和交流损耗。
At present, conventional low-temperature superconductors such as Nb3Sn strands have been extensively applied in high-energy and nuclear physics, as well as in magnetic resonance imaging systems. In this paper, a 3D finite element model considering sophisticated structure of superconducting filament bundles and metal matrix elements is built to deal with the electromagnetic behaviors of a Nb3Sn strand exposed to tension and bending loads. The mechanical constitutive relations of filament bundles and metal matrix are described with elastic and elasto-plastic axial stress–strain curve, respectively. The voltage–current characteristic of the metal matrix elements is determined with the Ohmic law, and that of the superconducting filaments follows thenpower relation. The stress–strain state is simulated and then implemented in the electromagnetic model, through the scaling law of ITER Nb3Sn strand. We find that the plasticity of copper and the twist filaments cause the enhanced inhomogeneous strain profile in a strand composite, compared to the strain profile in a strand with untwisted filaments. We also discuss the current/field profile, critical current degradation, and AC loss in the strand composite under the tension and bending loads.