Mechanical characterization and structural optimization of novel conductor on round core cables

Abstract In recent years, the continuous breakthrough of high magnetic field records has imposed increasingly stringent requirements on high-temperature superconducting (HTS) cables for the preparation of magnets, particularly regarding cooling efficiency, bending flexibility, and mechanical strength. To address these challenges, novel CORC cable designs featuring advanced core structures-including conductor-on-round-tube (CORT) and conductor-on-spiral-tube (HFRC)-have been developed. Although these designs enhance cooling efficiency and cable flexibility through modifications to the core structure, their impact on mechanical performance has not yet been thoroughly characterized. This paper systematically investigates the mechanical behavior of CORC cables with diverse core structures under axial tensile, torsion, and bending loads through a combination of theoretical analysis, FE simulation, and experimental validation. The research proposes optimization strategies focusing on two key aspects: (1) the winding parameters of HTS tapes, and (2) the geometric configuration of the core structure. Theoretical analyses demonstrate that variations in HTS tape winding angle and core radius significantly affect the axial strain in the tapes. The FE model evaluates three critical parameters: core outer radius, inner-toouter radius ratio, and helix angle of the spiral tube core. The numerical results indicate that the ratio between the inner and outer radii of the winding core should be maintained below 0.7, considering both the axial strain distribution of the HTS tapes and the deformation of the cable. Furthermore, the influence of the spiral tube core's helix angle on cable performance is strongly dependent on the applied mechanical load. These findings offer both theoretical insights and practical guidelines for the design, fabrication, and engineering implementation of HTS CORC cables.