Local and overall critical current of Bi2223-composite tape under applied tensile and bending strains

Abstract

Local and overall transport critical current IC and n-value at 77K of multifilamentary Bi2223-composite tape were studied under applied tensile and bending strains. The IC and n-value of the local elements constituting of the overall sample and those of the overall sample were measured for the voltage probe distances 10 and 60mm, respectively. The local IC as well as n-value varied along the sample length under both tensile and bending strains, while the critical current reduction process under the tensile strain was quite different from that under bending one; a big difference in damage among the local elements was found under tensile strain but not under bending one. While the damage process was different between the tensile and bending strains, the relation of overall IC and n-value to the local ones was described comprehensively by the voltage summation model. From the analysis of the experimentally observed critical current–applied strain relation of the local elements, the variation of the critical current determining factor “fracture strain–residual strain” along the sample length was revealed.