Trapped magnetic flux and fracture behaviors of long cylindrical superconductor with two collinear edge-cracks

In this work, to attempt to describe the multi-crack properties in bulk superconductors more clearly, we investigate the trapped magnetic flux and crack problem of a long cylindrical superconductor with two collinear edge-cracks during the field cooling magnetization process. The relationship between the crack lengths and the peak trapped flux in the cross section indicates that the trapped field in superconductors is significantly influenced by macro-defects. Based on the finite element method, we investigate the singular stress field induced by the complicated electromagnetic body forces. Numerical results obtained show that the stress intensity factors at the crack tips are affected by two important parameters: the external magnetic flux density and the length of the edge-cracks. As the external magnetic flux density decreases, the stress intensity factors increase quickly and then decrease gradually. That is to say that a peak value of the stress intensity factors appears during the magnetization process. For the crack length, the stress intensity factors generally change complicatedly because the crack length itself and the electromagnetic body forces generally play a role simultaneously. The analyses of the trapped magnetic flux and the fracture behaviors may be useful to researchers interested in cracking and mechanical failure of high-temperature superconductors.