3D multiscale modeling and simulation on the mechanical failure and performance degradation of ultra-high field high temperature superconducting magnets

Abstract Modeling the multi-physics coupling and quench behaviors of superconducting (SC) magnets is crucial for the design and application of large-scale high-field SC magnets. In this paper, a coupled electromagnetic-mechanical-thermal homogenization model is developed using the representative volume element method to characterize the multi-physics behaviors of high-field high-temperature superconducting (HTS) magnets. The effective properties of HTS coils, including the elastic-plastic constitutive curves, effective resistivity, thermal expansion coefficients, and thermal conductivity are predicted with the homogenization model. On this basis, the macroscopic multi-physics behaviors of the HTS magnet are numerically simulated. To accurately predict the performance degradation and quench behavior of the magnet, a refined sub-model is constructed in critical regions. Bidirectional mapping between the macroscopic simulation and the local refinement enables the balance between the efficiency and accuracy requirement. Furthermore, typical critical part (such as solder joints) in the magnet which is commonly found prone to damage or initiate quench, is simulated within the global homogenization and local refinement framework, revealing that delamination and irreversible degradation caused by the local stress concentration. The proposed modeling framework characterizes the irreversible degradation and quench initiation during magnet excitation and provides basis for the design and development of ultra-high-field HTS magnets.