Bending strain effects on the critical current in Cu-stabilized IBAD/EDDC processed SmBCO coated conductor tape

Abstract

Influences of bending strain on the critical current, I c, in Cu-stabilized IBAD/EDDC processed SmBCO coated conductor (CC) tapes were investigated at 77 K and self-field using a small-scale Goldacker type bending test rig. Considering the location of the superconducting layer against the neutral axis, tensile and compressive bending strains were applied to the SmBCO coating layer and the strain effect on I c degradation was discussed. Under tensile bending strain, the I c decreased monotonically but recovered reversibly up to the irreversible strain limit. Under compressive bending strain, however, the I c increased but in some cases it suddenly dropped after straightening due to the delamination of the copper stabilizer. Also, repeated bending strains were applied to Cu-stabilized SmBCO CC samples in order to observe the behavior of I c under cyclic loading. I c Initially decreased with the application of 0.7% bending strain, but when the tape was subjected to repeated bending up to 100 cycles, no more degradation occurred. And finally, the I c almost recovered to I c0 when the tape was straightened.