Damage mechanism of REBCO coated conductor in CORC cables under electromagnetic loading

Abstract

The performance of Conductor on Round Core (CORC) cables in complex electromagnetic environments is crucial for the safe operation of large superconducting magnet systems. As a critical component, the delamination issue of rare-earth-barium-copper-oxide (REBCO) coated conductors plays an important role in the mechanical and electrical stability of CORC cables. In this paper, the distribution characteristics of current density, electromagnetic force, interfacial stress, and delamination damage of REBCO coated conductors in CORC cables under different background fields are presented using a combined electromagnetic damage model. The numerical results indicate that the magnitude and direction of the electromagnetic force vary periodically with the sinusoidal magnetic field. The frequency of the external magnetic field has minimal influence on the current density and electromagnetic force. When the magnetic field and the transport current intervene together, the interaction between the transport current and the shielding current induced by the magnetic field significantly changes the distribution of the current density and the electromagnetic force, which further affects the interfacial stress and the delamination propagation path of the cohesive layer. The magnitudes of current density and electromagnetic force are proportional to the slopes of the variation curves of the transport current and magnetic field. Notably, in both scenarios, the interfacial shear delamination stress shows a clear tendency to concentrate at the edges of REBCO coated conductor, which is the primary factor driving interfacial delamination and crack propagation. Therefore, accurately measuring the shear delamination strength of REBCO coated conductors is highly significant for determining their operational limits under multi-field conditions.