Fracture problems of a superconducting slab with a central kinked crack

Abstract

In this work, the central kinked crack problem is investigated for a long rectangular superconducting slab under electromagnetic forces. The distributions of both the current density and the magnetic flux density in the slab are obtained analytically in the Kim critical state model for both the zero-field cooling and the field cooling magnetization processes. And based on the finite element method, the stress intensity factors at the crack tips for decreasing magnetic fields are numerically calculated. Numerical results obtained show that the zero-field cooling activation process generally has more significant influence on the stress intensity factors than the field cooling activation process, and that for every activation process, as the applied field decreases, the superconducting slab is most dangerous when the currents in the crack region are just be influenced. In general, both the maximal mode-I stress intensity factors (SIFs) and mode-II SIFs decrease with the increasing of either the introduced dimensionless parameter p in the Kim model or the crack length. However, the effects of kinked angles on the SIFs are complex. The present study should be helpful to the design and application of high-temperature superconductors.