Analysis of torsional deformation-induced degeneration of critical current of Bi-2223 HTS composite tapes

Abstract

A deformation-induced degradation model based on Weibull distribution function of statistical damage of superconducting filaments is developed to explore the influence of the torsional displacement on the critical current of Bi-2223 high temperature superconducting (HTS) composite tapes. It is extended in view of the critical current degradation mechanism of HTS tapes under uniaxial deformation. A longitudinal strain is introduced to unify the relation between uniaxial and torsional strain for the tapes. The extended model shows good predictions on the critical current degradation of the HTS tapes with torsional deformation in comparison with experiment data. The quantitative analysis indicates that the tensile longitudinal strain arised from torsional deformation plays a dominant role for superconducting filaments damage evolution compared to the compressive one, in which the irreversible degradation is always induced to remarkably reduce the critical current. Furthermore, a structural optimization design to enhance the carrying-current ability is achieved where the superconducting core should be less located at the tensile region of the HTS composite tapes.