Interaction of Two Parallel Cracks in REBCO Bulk Superconductors under Applied Magnetic Field

Interactions of two collinear and parallel a/b-plane cracks in REBCO (where RE is a rare-earth element and usually Y is adopted) bulk superconductors under the Lorentz force resulted from the applied magnetic field are studied. By using the derived boundary integral equation for the crack problem of a cylindrical bulk superconductor under the applied magnetic field, we comprehensively investigate the stress intensity factor (SIF) of modes I and II at the crack tips of the two collinear and parallel cracks with their sizes, relative positions and the applied magnetic field. The calculated results show that in most cases, the SIF of mode I is found to be about tens of times of the one of mode II, and all the SIFs are always proportional to increase in the applied magnetic field, and the cracks near the center are more dangerous due to the larger Lorentz force.