Effects of Bending Strain on Critical Current of Bi2223/Ag Tapes

Bending stress-strain characteristics and effect of bending fatigue on critical current of Bi2223/Ag tapes are investigated at 77K under self field.The results shown that critical current I_c reduction is due to the micro cracks of superconductive ceramic core caused by the bending strain and thermal cycle.Experimental study found that I_c declined obviously when the bending strains of tapes was more than 0.3% and significant decrease of I_c occurred within 4 cycles and then the decrease became gentle in repeated bending test.Therefore the bending strain of Bi2223/Ag tapes should not exceed 0.3% in application,and Bi2223/Ag tapes should be bended as few times as possible in process of production and use.