Evaluation of Young's modulus of RE123 bulk superconductors by three point bending tests

In order to investigate the evaluation method of the Young's modulus of RE123 single-grain bulk superconductors, 3-point bending tests have been carried out at room and liquid nitrogen temperatures. An attempt to evaluate it from the measurements of deflection of the specimen with 3 mm thickness was made. The consistent stiffness of the test machine including the jig was obtained by using a dummy specimen. For the test of the bulk, increasing repeated load within a level less than the fracture load was applied to stabilize the loading condition. The Young's modulus calculated by using the deflection of the bulk specimen obtained subtracting the machine stiffness coincided with that obtained by the conventional method, where the strain gage was adhered to the specimen. The effects of specimen thickness and the oxygen annealing sequence with respect to specimen cutting were also investigated.