CORC(conductor on round core)超导电缆是一种基于REBCO(rare-earth barium copper oxide)导体的高温超导电缆，已经成为迄今为止最灵活的高温超导(HTS)导体之一。然而，由于超导REBCO陶瓷材料的脆性，临界电流表现出敏感的应变依赖性，即临界电流与应变密切相关。该材料的应变一旦超过临界值，就会引发明显的衰减。除此之外，由于带材缠绕和电缆绞合后的复杂变形，切实存在一个实际性的挑战，即如何准确预测电缆超导带材在各种变形下的轴向应变。在本文中，我们建立了分析模型，可以用来准确计算CORC电缆的超导带材在电缆内芯上缠绕、电缆弯曲和扭曲变形等实际条件下的轴向应变。并且通过比较分析结果与有限元数值结果和实验数据，验证了分析模型，即超导带的临界电流随CORC电缆的核心直径而变化。在轴向应变结果的基础上，进一步确定了临界参数，即超导层的轴向应变恰好达到临界应变时的参数，如临界核心直径、临界弯曲直径和临界绞距等。对CORC电缆中REBCO超导带材的应变分析研究将有助于CORC电缆的加工和进一步设计高水平的超导线圈和磁体。
Strain analysis of the superconductor REBCO tape of CORC cables under winding,bending and twist deformations
Conductor on round core(CORC)cables are superconductor rare earth-barium-copper-oxide(REBCO)based conductors that allow for high operating currents and have been becoming one of the most flexible high temperature superconducting(HTS)conductors to date.Nevertheless,due to the brittle nature of superconductor REBCO ceramics,the critical current exhibits a sensitive strain dependence,i.e.,the critical current varies closely with strain,and especially raises a significant degradation once the strain exceeds a critical value.And,due to the complex deformation of tape winding and after cable stranding,firstly there is a practical challenge that how to accurately estimate the axial strain of the superconductor tape of cables under various deformations.In this paper,we developed the analytical models that can be used to accurately calculate the axial strain of the superconductor tape of CORC cables under the practical conditions of tape winding on the cable core,the cable bending,and twist deformations for stranding.The analytic model was validated by comparing the analytic result both with FEM numerical result and experimental data that the critical current of the superconducting tape varies with the core diameter of CORC cables.Further,on the analytic models,the axial strain,and the dependence on the core diameter and winding angle,the bending diameter,and the strand pitch were obtained respectively for CORC cables under tape winding,cable bending,and twist deformations.Particularly,the critical parameters,which are here defined at which the axial strain of the superconductor layer just reaches the critical strain,such as the critical core diameter,critical bending diameter,and critical pitch were determined.Thus,the analytic study of the strain of the superconductor REBCO tape of CORC cables will be helpful for CORC cables processing and further the design of high-level superconducting coils and magnets.
CORC cableSuperconductor REBCO tapeStrain analysisWindingBending and twist deformations
彭昱昊、苟晓凡
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College of Mechanics and Materials,Hohai University,Nanjing 211000,China
CORC cable Superconductor REBCO tape Strain analysis Winding Bending and twist deformations
National Science Foundation of ChinaNational Science Foundation of China
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NSTL
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