Short-term and long-term mechanical characteristics of BSCCO steel-reinforced tapes

An investigation on short-term and long-term mechanical characteristics of Bi₂Sr₂Ca₂Cu₃O_y reinforced tapes is presented in this paper. Results of critical current measurements obtained after bending, as well as during application of tensile stress and strain, are shown. Data are processed to provide a threshold model for the bending test, according to which bending on large-diameter mandrels does not provide appreciable damage to superconductor tapes. The values of critical current density derived from tensile stress and strain are investigated by the Weibull cumulative function, showing the existence of two distinct failure modes, determined by different strengths of reinforced tapes. This statistical analysis provides a methodology for a feasible quality control test on superconductive tapes. Long-term behavior evaluation, carried out through life lines derived from tests under different levels of stress and strain, indicate that reinforced tapes show largely improved endurance with respect to nonreinforced ones.