Damage evolution under bending and tensile stress and its influence on critical current of Bi2223/Ag superconducting composite tape

The influence of bending and tensile damage introduced at room temperature on the critical current at 77 K under zero magnetic field of a multifilamentary Bi2223/Ag/Ag alloy superconducting composite tape was studied. From the analysis of the tensile stress–strain curve, the residual strain and intrinsic tensile-fracture strain of Bi2223 filaments were estimated, with which the measured change of critical current with tensile strain was accounted for. A simple model, in which the damage evolution in both tensile and compressive sides was incorporated, was proposed to describe the change in critical current with bending strain. The application of the model to the experimental result indicated that the intrinsic compressive-strength of Bi2223 filaments, determining damages in the compressive side, is about five times higher than the tensile strength.