• Progress in Superconductivity and Cryogenics
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• v.18 no.3
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• pp.6-9
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• 2016

The enhancement of mechanical properties of coated conductor (CC) tapes in practical application are usually achieved by reinforcing through lamination or electroplating metal layers on either sides of the CC tape. Mechanical or electromechanical properties of the CC tapes have been largely affected by the lamination structure under various loading modes such as tension, bending or even cyclic. In this study, the influence of brass laminate volume fraction on electromechanical properties of RCE-DR processed Gadolinium-barium-copper-oxide (GdBCO) CC tapes was investigated. The samples used were composed of single-side and both-side laminate of brass layer to the Cu-stabilized CC tape and their $I_c$ behaviors were compared to those of the Cu-stabilized CC tape without external lamination. The stress/strain dependences of $I_c$ in laminated CC tapes under uniaxial tension were analyzed and the irreversible stress/strain limits were determined. As a result, the increase of brass laminate volume fraction initially increased the irreversible strain limit and became gradual. The corresponding irreversible stress limit, however, showed no difference even though the brass laminate volume fraction increased to 3.4. But the irreversible load limit linearly increased with the brass laminate volume fraction.

• Progress in Superconductivity and Cryogenics
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• v.20 no.4
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• pp.36-40
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• 2018

In this study, the electromechanical properties in Sn-Cu double layer stabilized GdBCO coated conductor (CC) tapes with and without external lamination under uniaxial tension were examined at 77 K and self-field. Their irreversible stress and strain limits were determined using a loading-unloading scheme based on different critical current ($I_c$) recovery criteria. The repeated tests were performed and statistical estimation was done to check the reproducibility depending on the criterion adopted in evaluating the electromechanical properties. From the results, it showed that the Sn-Cu double-layer stabilized CC tapes have the higher irreversible stress limit, but lower irreversible strain limit as compared to brass laminated ones. Through the repeated tests, it can be found that a small scattering of irreversible limits existed in both CC tape samples. Finally, similar strain sensitivity of $I_c$ in both CC tapes was obtained.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.29-33
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• 2013

The understanding of the strain dependence of critical current, $I_c$, in the reversible region is important for the evaluation of the performance of coated conductor (CC) tapes in practical applications. In this study, the stress/strain tolerance of $I_c$ in GdBCO CC tapes with stainless steel substrate stabilized by additional Cu and brass laminate was analyzed quantitatively through $I_c$-strain measurement at 77 K under self-field. The variation in irreversible strain limits of CC tapes by the addition of stabilizing layers was analyzed through the consideration of the pre-strain induced on the GdBCO coating film. The results were then compared with the ones previously reported for GdBCO CC tapes with Hastelloy substrate. As a result, GdBCO CC tapes with stainless steel substrate showed much higher strain tolerance of $I_c$ as compared with those adopting Hastelloy substrate.

• Progress in Superconductivity and Cryogenics
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• v.14 no.2
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• pp.8-11
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• 2012

In order to recognize the allowable bending diameter in coils, the strain as function of diameters is evaluated. The irreversible strain limits of $I_c$ in the easy and hard bending modes were measured. Strains were calculated at the coating film in the easy bending and at outer edge or inner edge in the hard bending of the CC tape, respectively. The tape geometry subjected to bending procedures is considered from the current industrial spool winding operation. Through the linear superposition of strain induced in different bending modes regarding the expressions, the appropriate design for critical bending diameter is suggested. Results proved that the existence of buckling resulting from bending in hard direction when applied strain exceeded 0.6% is possible. The depicted results showed that the strain limit as a viable parameter should be considered for future purposes.