Degradation Due to Bending Fatigue Strain in YBCO Coated Conductors

A YBCO coated conductor is expected to be a high performance superconductor. To design applied superconducting machines with YBCO conductors, evaluation of not only the superconducting property but also the mechanical property is very important. In particular, the performance against fatigue cycles should be investigated for practical use of the machines. Hence, we measured degradation of YBCO conductors due to bending strain including fatigue. First, we show dependence of the bending strain on critical currents of the conductor. And next, we give the bending strain to the conductor and then release the strain to zero to estimate whether or not the critical currents changes before and after the bending. This test is so called the reversible/irreversible property test. Finally, we show the dependence of the critical currents of the conductor on repeated bending cycles, namely the fatigue test.