Statistical analysis of the electromechanical behavior of AgMg sheathed Bi2Sr2CaCu2O8+x superconducting tapes using Weibull distributions

Abstract

Manufacturing of AgMg sheathed Bi2Sr2CaCu2O8+x superconducting tapes involves multiple processes. Microstructural studies across tape sections have shown that the microstructure is nonuniform across the tape. These nonuniformities are largely due to manufacturing defects, even in well-controlled manufacturing processes. Consequently, the electrical and mechanical properties vary in these different sections. Here, we report results from analyzing the electromechanical properties of AgMg sheathed Bi2Sr2CaCu2O8+x tapes in different sections using a statistical approach. 24 samples were studied at strains of 0%, 0.25%, and 0.349% for a total of 72 samples. The probability of electrical and mechanical failures of the tapes is then analyzed using two- and three-parameter Weibull distributions. It is found that the mechanical failure of these tapes is homogeneous, consistent with failure in the AgMg sheath, but that the electromechanical failure is inhomogeneous within the conductor and as a function of strain, indicating that this failure is dictated by failure in the inhomogeneous ceramic oxide superconducting filaments. This has important implications for the designs of superconducting magnets.

Preliminary investigation of Ic homogeneity along the longitudinal direction of YBCO coated conductor tape under tensile loading

“…With this information, the introduction of employing a statistical analysis would be necessary, similar to the cases reported for BSCCO tapes [19,23]. For statistical analysis of the I c degradation behaviour, statistical analysis of I c characteristics under various strain values should be considered in the electro-mechanical aspect, namely, the irreversible strain limit (or strain corresponding to the yield stress), the strain corresponding to the proportional limit, and the strain value where scattering of I c initially occurred.…”

Distribution of normalized critical current of bent multifilamentary Bi2223 composite tape

“…[3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Under no applied strain, the critical current is different from specimen to specimen and from position to position within a specimen. [18][19][20][21][22][23][24] Under applied strain, the damage evolution behavior is also different from specimen to specimen and from position to position within a specimen, resulting in wider distribution of critical current.…”

Theory analysis of critical-current degeneration in bended superconducting tapes of multifilament composite Bi2223/Ag

“…For a bent Bi2223-composite tape, ideally, one side of the neutral axis is stretched, and the other side is compressed. From the view of damage of fiber-reinforced composites, the ratio of the number of undamaged superconducting filaments to the total number of superconducting filaments under tension and compression conditions satisfies Weibull distribution, as follows [22][23][24][25]:…”