Prediction of critical current-bending strain relation of Bi2223 composite tape using residual strain of filaments, load-strain curve and geometry of cross-section

摘要

A prediction method of the critical current-bending strain relation of the Bi2223 composite tape, which was bent at room temperature and cooled down to 77 K for measurement of critical current, was presented. The present method consisted of (a) measurement of residual strain of Bi2223 filaments at room temperature in the sample length direction by the X-ray diffraction method, (b) estimation of tensile fracture strain of the filaments from the analysis of the load-strain curve at room temperature, (c) measurement of geometrical factors such as the thickness of the sample and shape of the core by observation of the cross-section with optical microscope, and (d) calculation of the critical current as a function of bending strain by using the measured parameters mentioned in (a)-(c). The predicted variation of critical current with bending strain by the present approach described well the experimental one.