Three-dimensional electromagnetic-mechanical coupled modelling of multilayer HTS REBCO coated conductors considering strain effects

Rare-earth barium copper oxide (REBCO) coated conductors, known for their high critical current density and excellent high-field performance, are promising candidates for applications in high-field scientific magnets, nuclear magnetic resonance (NMR) magnets, fusion magnets and electrical machines. Although significant progress has been made in numerical simulations of the electromagnetic performance, the coupled effects of mechanical stress on the electromagnetic response, especially under high magnetic fields and large currents, including critical current degradation and conductor mechanical failure, still require further investigation. Since high-temperature superconducting (HTS) REBCO is a typical brittle material and highly sensitive to mechanical strain, its critical current density distribution is significantly affected by mechanical factors under complex operating conditions. In this paper, a three-dimensional electromagnetic-mechanical coupled model based on the H-formulation was developed in the COMSOL Multiphysics to simulate the strain-dependent behavior of multilayer REBCO tape. A mechanical loading apparatus was also designed to experimentally investigate the impact of mechanical loading on critical current degradation. The experimental results provided reliable validation for the proposed model, while the simulations further revealed the internal stress-strain distribution across different layers and its impact on current-carrying capability. The differences in the critical current density of the REBCO tape with and without considering strain effects were compared, which represents a key issue that has not been explored in previous numerical models. This work is useful for developing large-scale HTS cable and highfield magnet models, offering practical insights that can support their design and application.