Ultimate tensile strength of an artificial bulk superconductor with voids

Rare earth based bulk superconductors originally have many voids and cracks. Thus their ultimate tensile strengths are not material constants but apparent ones depending on the voids and cracks in each bulk. In this study, based on the observations of the surface of the actual specimens, artificial samples with voids were generated for numerical stress calculations. The sizes of voids in an artificial specimen were assumed by the probability distribution function expressing the results of the observations, while the locations of voids were randomly assumed. Numerical calculations were repeatedly conducted to obtain the statistical results of the stress concentration factors around voids. The scatter of experimental strength and Young's modulus among the specimens having linear stress-strain curves can be predicted by the evaluations proposed in this study.