Experimental Investigation on the Contact Mechanical Characteristics of Superconducting Strands in the CICC Cross-Section

Interstrand force is related to the understanding of the mechanical response of superconducting strand under large electromagnetic force, which is important to the safety of the ITER magnet structure. A two-dimensional discrete element method and relevant simulations to quantitatively characterize the contact force behavior on the superconducting strands in the ITER cable-in-conduit-conductor cross-section has been performed by Zhu et al. (2012, Supercond. Sci. Technol. , 25 , 125011). Here, we report direct measurements of the contact forces inside a two-dimensional system of photoelastic disks that are subjected to a single-direction compression, and obtained the contact force (including force chain) and its direction. Then, we can conclude that the contact force distribution among strands is strongly anisotropic. We use a probability density function to analyze this inhomogeneity. The influences of a helium channel on the contact force behavior are also taken into account. Notably, the energy loss during this compression is also calculated based on the experimental results, which are considered to be suitable for providing qualitative predictions of the contact force behavior among the superconducting strands under electromagnetic force.