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 Ic reduction is due to the micro cracks of superconductive ceramic core caused by the bending strain and thermal cycle.Experimental study found that Ic declined obviously when the bending strains of tapes was more than 0.3% and significant decrease of Ic 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.