Bending deformation and its influence on critical current in Bi2223 composite superconducting tapes

Abstract

The strain dependence of the critical current, I c, of Ag and Ag-alloy sheathed Bi2223 composite superconducting tapes has been studied under bending deformation. The tensile stress–strain behavior of the composite tapes was first analyzed to determine several unknown parameters such as Young’s modulus, yield strength and the thermal expansion coefficients of each component. In this analysis, these were inversely decided to meet the global tensile stress–strain behavior including intermediate unloading and reloading processes and the thermal expansion of the composite tapes. Thus evaluated values were used for the bending analysis in which the movement of the neutral axis was taken into account. Based on the analyzed strain distribution, the relative decrease of the critical current with the increase of the Bi2223 tape curvature was calculated from the volume fraction of the broken filaments. The calculated value agreed well with the experimental results.