有限元法模拟Nb_3Sn线材的应变分布

FEM analysis of strain for Nb_3Sn composite superconductors

Nb3Sn超导磁体正常运行时,复合超导线材将受到大的机械载荷(如温度载荷、轴向拉伸和电磁力),其超导电性可能发生可逆和不可逆的退化。针对Nb3Sn线材经高温热处理后冷却到4.2K所产生的热应变,对复合线材结构建立详细的三维有限元分析模型,解决了一维模型不能详细模拟应变分布的问题,从微观尺度仿真了导体内部的应变分布,阐明了导体不同组份材料上热应变分布的特点。在此基础上,进一步分析了对Nb3Sn复合导线施加轴向拉力时,内部Nb3Sn芯丝上由压应变向拉伸应变的转换过程。

During normal operation of Nb3Sn superconductors, Nb3 Sn composite superconductors subject to large mechanical loading （such as temperature loading, axis stretching and electric -magnet force）,which disturbs the current flow and causes reversible and irreversible degradation of superconducting properties. This paper focused on the problem that the conductors were subjected to thermal stress as Nb3Sn wires were heat- treated at high temperatures and operated usually at 4. 2K. One dimensional finite element model could not detail model geometries with large filament amount. A three dimensional finite element model was used to describe the thermal strain and of Nb3 Sn wires. The models developed in this work described axial stress and strain in the cross section.