Mechanical Simulation of 2G HTS Tapes and Stacks During Localized Temperature Increase

Abstract

High-temperature superconductor (HTS) materials have emerged as promising candidates for high-field magnets due to their superior critical current density, temperature, and magnetic fields. During magnet quench, high current density can quickly lead to local temperature increase and temperature gradient that can potentially damage the coil. This paper presents an analysis of the mechanical impact of the large thermal gradients. The study employs 3D finite element method (FEM) simulations to investigate the mechanical responses of second-generation HTS tapes to different hotspot temperature profiles. The focus is on analyzing the axial tape strain, normal stress and the various shear stresses in tape layer interfaces. We consider both single tapes and tape stacks. The normal zone propagation is not simulated, but we examine different end-temperature profiles to identify the critical thermal conditions that may lead to too large strain or stress. The results suggest that induced axial strain can exceed the elastic limit or lead to irreversible critical current reduction. Also, the shear stress computed using the Mohr-Coulomb criterion may reach very high values potentially leading to mixed-mode delamination. Future studies are needed to verify the damage methods after high temperatures and help in determining the maximum safe temperature in magnet design. The results highlight the importance of mechanical boundary conditions in this type of numerical or experimental study.