Change of the V–I curve and critical current with applied tensile strain due to cracking of filaments in Bi2223composite tape

Abstract

The critical current at 77 K of multifilamentary Bi2223 composite tape was studied under appliedtensile strain experimentally and analytically. Beyond the irreversible strain, the critical currents(IC) decreased significantly with increasing applied tensile strain(εc), due to the enhanced cracking of the Bi2223 filaments. The voltage generationin the voltage–current relation was calculated by the current share modelin which the transport current is shared by the Bi2223 filament and Agnear the cracked portion. Then the critical current was estimated with a1 µV cm−1 criterion. By the application of the current share model to the experimental result, theeffective crack length responsible for the reduction in critical current was estimated, withwhich the change of critical current could be described satisfactorily as a function ofapplied strain.