Strand buckling analysis under large electromagnetic force by using structural mechanics and strand trace measurement

电缆导管导体通常被用作最有前途的大型聚变磁体导体，它由扭曲的股和插入称为导管的金属外壳的子电缆组成。在评估导体性能的温度裕度的测试活动中，随着传输电流循环次数的增加，温度裕度越来越差。根据对导线的目视检查，由于导线运动引起的导线屈曲可能会导致导线劣化。为了研究屈曲的机理，运用结构力学方法对钢绞线的运动进行了计算。结果表明，热收缩力引起的滑移运动会引起位移。对滑移距离的验证进行了试验研究，其结果与计算得到的滑移量一致。研究结果对大型磁体导体设计活动的开展具有指导意义。

The Cable-In-Conduit conductor is commonly used as the most promising one for large-scale fusion magnets, which consists of twisted strands and sub-cables inserted into the metal case called conduit. During test campaign to evaluate the temperature margin for the assessment of the conductor performance, the temperature margin was getting worse as the number of transport current cycle increases. According to the visual inspection of the conductor, strand buckling due to strand movement might cause the deterioration. In order to investigate the mechanism of the buckling, I calculated the strand movement by using structural mechanics. The results showed the slip motion due to thermal contraction force would cause the displacement. Experimental investigation for certification of the slip distance carried out and its result supported the slip obtained by the calculation. The results will useful for the development of the conductor design activities for large scale magnets.