Assessment of strain of Bi2223 filaments in bent Ag-sheathed superconducting composites by synchrotron radiation

Okuda, Hiroshi; Shin, J.K.; Iwamoto, Shinichiro; Morishita, Kohei; Mukai, Yasuhiro; Matsubayashi, Hiroaki; Ochiai, Shojiro; Otto, A.; Harley, Edward J.; Malozemoff, A. P.; Sato, Masugu

doi:10.1016/j.scriptamat.2007.12.003

Cited by 7 publications

(3 citation statements)

References 12 publications

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“…In the Bi2223 composite tape, only the tensile side is damaged up to around 1.0% bending strain, as has been verified by the X-ray diffraction analysis. 18) In the present work, we consider the case where only the core for y > 0 (tensile side under the bending strain) is damaged. The experimental results are described for this condition, as shown later in Section 4.2.…”

Section: Model Smentioning

confidence: 99%

Applicability of Weibull Distribution to Description of Distributed Normalized Critical Current of Bent-Damaged Bi2223 Composite Tape

et al. 2010

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Critical current of bent-damaged Bi2223 composite tape differs from specimen to specimen. To describe the distributed critical current values of specimens, the three-parameter Weibull distribution function has been employed and has been demonstrated to describe the experimental results. In the present work, the reason for this was discussed by modeling analysis of the experimental results in a round robin test of VAMAS/TWA16. The distribution of the measured normalized critical current values was described well by using the damage evolution approach, in which the difference in damage evolution among the specimens was correlated to the distribution of critical current values. From this approach, the three-parameter Weibull distribution function for critical current values was derived, which gave almost the same parameter values for the minimum critical current, scale parameter and shape parameter as those obtained by the direct application of the Weibull distribution function to the experimental results. Based on this result, the reason why the normalized critical current values of bent-damaged composite tape is described by the three-parameter Weibull distribution function was accounted for in a quantitative manner by the difference in damage evolution among the specimens.

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Section: Model Smentioning

confidence: 99%

Applicability of Weibull Distribution to Description of Distributed Normalized Critical Current of Bent-Damaged Bi2223 Composite Tape

et al. 2010

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“…In the modeling below, bending damage of Bi2223 tapes is counted only for the tensile side above the neutral axis due to the following reason. In our former work [21], the strains of Bi2223 filaments at the Bi2223/Ag sheath boundary in tensile and compressive sides have been studied by x-ray diffraction utilizing synchrotron radiation for a composite tape supplied by another company. The results showed that the fracture strain is asymmetric between tension and compressive stresses.…”

Section: Formulation Of the Distribution Of Normalized Criticalmentioning

confidence: 99%

Analysis of critical current distribution of bent Bi2223 composite tapes by unifying parameter approach and its application to the description of average critical current–bending strain relation near the average irreversible strain

Ochiai¹,

Okuda²,

Sugano³

et al. 2009

Supercond. Sci. Technol.

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When the critical current of bent Bi2223 composite tape is measured for many specimens, the critical current value is different from specimen to specimen, being distributed from low to high values. We need to characterize the distribution of critical current at various applied strains and also to predict the distribution of irreversible strain for reliability and safe design. The present work attempted to describe them from the statistical viewpoint. In the analysis, the unifying parameter approach proposed recently by the authors was employed, in which the difference in damage evolution and critical current among the specimens was correlated with the distribution of the unifying parameter that refers to the tensile damage strain of Bi2223 filaments in composite tapes. By application of this approach to the measured critical current values under various bending strains for three Bi2223 composite tapes from different suppliers (VAM1, VAM2 and VAM3 used as the common test samples in the round robin test of VAMAS/TWA16), the unifying parameters were estimated and were formulated by the Weibull distribution function. With the formulated distribution function of the unifying parameter, the distributions of the critical current at various strains, the distribution of the irreversible bending strain and the average critical current-bending strain relation near the average irreversible bending strain could be described satisfactorily.

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“…Synchrotron radiation is a useful tool to probe the strain state of a superconductor in a composite. Okuda et al have reported in situ strain measurement using synchrotron radiation for Bi2223 composite tapes [15][16][17]. The residual strain of the Bi2223 filament was directly evaluated with the extracted oxide filaments as a reference in the stress-free state.…”

Section: Introductionmentioning

confidence: 99%

The direct evaluation of the internal strain of biaxially textured YBCO film in a coated conductor using synchrotron radiation

Sugano

Machiya

Osamura³

et al. 2008

Supercond. Sci. Technol.

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The internal strain state of the superconducting film in a coated conductor should be clarified to understand the strain effect on the critical current (Ic). We have developed an in situ strain measurement technique using synchrotron radiation for YBa2Cu3O7−δ (YBCO) coated conductor, and the internal strain of the YBCO film was directly evaluated. YBCO powder obtained from the film in the coated conductor was used as a reference of the zero-strain state. Shifts of the Bragg peaks of the (020) plane of the YBCO film were measured under applied tensile strain, and the internal strain was calculated from the change in the interplanar spacing. The residual strain of the YBCO film in this coated conductor at room temperature (RT) was directly determined to be −0.061%. The fracture strain of the YBCO film was also evaluated from the relationship between the applied strain and the internal strain of YBCO. Surface observation of the coated conductor suggests that fracture initiates in the MgO buffer layer. The irreversible strain (εirr) determined by Ic–strain characteristics at 77 K was compared with the result from in situ strain measurement. The validity of our technique using synchrotron radiation is discussed.

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Assessment of strain of Bi2223 filaments in bent Ag-sheathed superconducting composites by synchrotron radiation

Cited by 7 publications

References 12 publications

Applicability of Weibull Distribution to Description of Distributed Normalized Critical Current of Bent-Damaged Bi2223 Composite Tape

Applicability of Weibull Distribution to Description of Distributed Normalized Critical Current of Bent-Damaged Bi2223 Composite Tape

Analysis of critical current distribution of bent Bi2223 composite tapes by unifying parameter approach and its application to the description of average critical current–bending strain relation near the average irreversible strain

The direct evaluation of the internal strain of biaxially textured YBCO film in a coated conductor using synchrotron radiation

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