管内电缆导体截面股线接触力行为分析

国际热核聚变试验堆(ITER)所希冀的是由管内电缆导体(CICC)绕制的超导磁体产生强磁场约束高温等离子体的运动,进而实现可控的热核聚变. CICC导体结构复杂,通常是由上千根NbTi/Cu或Nb3Sn/Cu经四级或五级绞缆加工而成,运行在极低温、大电流、强磁场复杂环境,承受的电磁力将引起股线间产生接触挤压变形,甚至引起股线的断裂,给装置安全性带来隐患.传统的CICC导体横截面股线接触力研究实验上多采用非实体的光弹模型,数值上采用不含颗粒变形的离散单元法(Discrete Element Method, DEM),均难以给出真实的CICC导体截面股线接触力特征.本文实验中采用真实的CICC导体,通过在横截面喷涂散斑的方式,采用数字图像相关法(Digital Image Correlation, DIC),给出了股线间的变形特征.理论上采用颗粒单元法(Granular Element Method, GEM),将DIC获得的股线变形作为输入参数,直接给出了CICC导体在横向压力作用下的横截面股线接触力的分布特征,并对接触力链大小和方向进行了统计分析.

Analysis on the contact force behaviors among strands of CICC conductor cross section

International Thermonuclear Experimental Reactor(ITER) hopes to achieve controllable thermonuclear fusion by constraining the motion of high temperature plasma by a strong magnetic field which is generated by superconducting magnets wound by the cable-in-conduit conductors(CICCs). The CICC structure is complex, usually with thousands of Nb Ti/Cu or Nb3 Sn/Cu twisted in four or five stages. It operates in a complex environment of extremely low temperature,high current and strong magnetic field. The electromagnetic force generated by the superconducting material will cause deformation, reduce its characteristic parameters and bring hidden trouble to the safety of the device. Traditional studies on the contact force of the cross-section strand of CICC mostly adopt non-actual object photoelastic model in the experiment, and numerically adopt discrete element method(DEM) without particle deformation. However, it is difficult to give the contact force of the cross-section strand closer to the real working condition. In this experiment, the deformation characteristics were calculated between strands of the prototype of CICC by spraying speckle on the crosssection and using digital image correlation(DIC). Theoretically, taking the strand deformation obtained by DIC as the input parameter of granular element method(GEM), the distribution characteristics of the contact force of the CICC conductor under the action of transverse pressure are calculated, and the size and direction of the contact force chain are statistically analyzed.