Mechanical and electromagnetic properties of CORC cables under combined loads of axial tension and transverse compression

Abstract

Conductors on round core (CORC) superconducting cables have a special construction that provides them with excellent mechanical performance and symmetrical electromagnetic properties, making them a promising option for high magnetic field magnets and accelerator magnets. In these applications, the combination of high engineering current density and high magnetic fields results in large electromagnetic forces or thermal loads acting on the CORC cable, which may lead to irreversible degradation of its properties. These loads typically appear in two perpendicular directions: axial tension by hoop stresses and transverse compression by radial stresses. Therefore, enhancing the irreversible strain limit in axial tensile and transverse compression deformation is imperative while minimizing magnetization losses during the design of CORC cables. This paper develops a finite element (FE) model that can be used to predict the mechanical and electromagnetic behaviors of CORC cables when subjected to axial tensile and transverse compressive loads. The irreversible strain limit for various combined axial tensile-transverse compression deformation modes is investigated from the critical current density reduction perspective. The distribution of axial strain in the ReBCO layer is analyzed. On this basis, a discussion of the effect of strain on electromagnetic properties is presented. In general, it can be observed that the irreversible strain limit of CORC cables exhibits greater sensitivity to axial tensile strain as compared to transverse compressive strain. Smaller winding angles are still the optimal choice regarding resistance to deformation and critical current degradation. The conclusions drawn in this paper will guide the design of future CORC cables.