A comparison of strain effect on critical current in Bi-2223 superconducting tapes in different bending modes

The influence of the bending strain on the critical current (I_c) in Ag alloy/Bi-2223 superconducting tapes was investigated at 77 K. The strain effect on I_c degradation in the different bending modes is discussed in terms of sample geometry and n-value. The I_c degradation behavior with bending occurring across the tape´s width direction called ´hard bending´ is discussed in particular, and compared with results under conventional bending tests known as ´easy bending´. It was found that I_c degraded with increases in the bending strain. In the case of hard bending, greater degradation in I_c occurred than under easy bending. This might be a result of the difference in the filaments cross-section of the tape and the generation of a new type of damage, such as local buckling, expected during hard bending. The n-value also decreased as the bending strain increased and its behavior was similar to the I_c-bending strain relationship.