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/sub c/) in Ag alloy/Bi-2223 superconducting tapes was investigated at 77 K. The strain effect on I/sub c/ degradation in the different bending modes is discussed in terms of sample geometry and n-value. The I/sub 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/sub c/ degraded with increases in the bending strain. In the case of hard bending, greater degradation in I/sub 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/sub c/-bending strain relationship.