Thermal effect on delamination and buckling of superconducting film-substrate structures

High-Temperature superconducting (HTS) film-substrate structures have great potential applications in magnets and superconducting cables that have great potential for high temperature superconducting wires in space solar power stations. The most important issue in the successful application of those structures is the delamination of interfaces. Therefore, in this paper, the delamination induced by electromagnetic force and temperature change in the superconducting film-substrate structure is studied. Energy release rates of delamination are given. It is found that thermal effect on the energy release rate is more significant when the electromagnetic force increases. If without electromagnetic force, as the crack length reaches at its critical value, the film will be buckling and the crack becomes a mixed crack. The closed-form solution of the energy release rate of the mixed crack is provided. On the other hand, when the crack length is smaller than its critical buckling length and the crack is the mode II crack. The influence of the stress intensity factor of the mode II crack is more significant for a thicker film. This suggests that the film should be designed to be thinner. This study is useful for engineers to design HTS film-substrate structures.