Evaluation of Irreversible Strain/Stress Limits for Ic Degradation in Practical REBCO CC Tapes Under Uniaxial Tension

Shin, Hyung-Seop; Bautista, Zhierwinjay

doi:10.1109/tasc.2017.2788078

“…When the YBCO CCs were soldered onto both surfaces of the original stainless steel tape, the ε irr of the sample is 0.47%, which is larger than the original YBCO CC. This result is similar to that obtained by Shin et al [20][21][22], that ε irr of original superconducting CCs can be increased by additional lamination. For the original YBCO CC, I c decrease with the increasing of compression strain [10].…”

Section: ε Irr Of the Pre-compressed Ybco Ccssupporting

confidence: 91%

“…They enlarged the elastic strain region of the Hastelloy substrate with electro-polishing and smooth rolling and concluded that utilizing the continuous yielding substrate with high elastic limit can improve the strain tolerance in the superconducting CCs. Shin et al [19][20][21][22][23] replaced the Hastelloy with stainless steel and soldered the copper stabilization layer on the surface of GdBCO CCs, which greatly increased ε irr and irreversible stress limits (σ irr ). They also pointed out that ε irr was higher when the stabilization layer was soldered onto the side near the GdBCO layer than when it was soldered onto the other side.…”

Section: Introductionmentioning

confidence: 99%

Controllable rectification on the irreversible strain limit of 2G HTS coated conductors

Su

¹

,

Huang

²

,

Liu

³

et al. 2021

Supercond. Sci. Technol.

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The second generation high-temperature superconducting coated conductors (CCs) have excellent electrical and mechanical properties, and are extensively used in superconducting devices such as fault current limiters, magnets and motors. During the operation of these superconducting devices, superconducting CCs inevitably bear the combination of electromagnetic force and thermal mismatch stress, resulting in straining of YBa2Cu3O7− δ (YBCO) layer along the tape length. It is well known that the strains of superconducting CCs cause degradation of critical current (I c). Generally, the irreversible strain limit ( ε irr ) is used to characterize the phenomenon that I c of superconducting CCs degrades with axial strain. When the axial strain of superconducting CCs is less than ε irr , I c can be reversibly recovered by over 99% after being unloaded. Therefore, ε irr is a key parameter for the design and application of superconducting CC devices. For this reason, to carry out a practical engineering method for improving ε irr of superconducting CCs has become a challenge and aroused interests among researchers. This study is based on the idea of precompression. A 316LN stainless steel tape was pretensioned at 77 K to improve its elastic strain limit. Then, two superconducting CCs were soldered onto both surfaces of pretensioned stainless steel tape respectively. As a result, ε irr of the superconducting CCs can be controlled manually with different precompressions. Taking YBCO CCs produced by SuperPower Inc. as an example, the measurement results show that the ε irr of the YBCO CCs increased from 0.39% to 0.73%. Meanwhile, the thickness of the sample did not increase more than once.

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“…This includes determining characteristic strain/stress limits, also known as reversible or irreversible limits, that manifest whether there is any permanent or unrecoverable I c degradation due to damage to the superconducting layer [12][13][14][15][16]. A number of studies on the reversible strain effects of I c in practical 2G rare-earth barium copper oxide (REBCO) CC and first generation (1G) bismuth-strontium-calcium copper oxide (BSCCO) tapes have been reported [17][18][19][20][21]. Therefore, depending on application, it is necessary to determine the reversible strain (or stress) limit below which the permanent degradation in I c is zero or negligible.…”

Section: Introductionmentioning

confidence: 99%

Establishing a test procedure for evaluating the electromechanical properties of practical REBCO coated conductor tapes by the uniaxial tension test at 77 K

Shin

¹

,

Bautista

²

2019

Supercond. Sci. Technol.

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Nowadays, the superior electrical and mechanical properties of second generation (2G) practical coated conductor (CC) tapes make them viable options for various applications such as power cables, magnets and coils. The CC tapes are composite conductors where the constituent layers are directly affected by the mechanical and the electromechanical properties of the superconducting layer under operating conditions. It is therefore important to investigate the strain effect on the critical current (I c ) and to determine the irreversible limits for I c degradation in CC tapes. However, standards or codes for testing the electromechanical properties of hightemperature superconductors are lacking. Therefore, the establishment of a test method or procedure for determining the electromechanical properties of 2G CC tapes in both engineering and practical aspects is needed. This study is a standardization activity, wherein the strain/stress sensitivity of I c and the reversible strain/stress limits for I c degradation of practical CC tapes using uniaxial tension tests were evaluated at 77 K and self-field. The reversible strain/stress limits of CC tapes were defined and the reversible recovery of I c during loading-unloading was measured when using the 99% I c (ε) recovery, 99% I c0 recovery and 95% I c0 retention criteria. The electromechanically determined irreversible limits were also compared to the mechanically determined stress and strain at the yield point. The obtained reversible stress limits showed a similar value regardless of criteria adopted, excepting Sample 2. However, the irreversible strain limit value obtained using the 99% I c (ε) recovery criterion showed the largest value as compared to the cases using other criteria. Through repeated tests, the electromechanical test procedure of the CC tapes was evaluated based on statistical estimates. The obtained results can provide a fundamental basis for establishing test procedures comparing the criterion that should be considered in determining irreversible limits, whether normalized to the original state I c value, I c0 or determined using the reversible degradation of I c (ε) at residual strain, when unloaded.

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“…Cu (20 µm) [10] Andong National University 2022 Clip [11] Andong National University 2019 Solder [13] Andong National University 2018 Solder [15] Southwest Jiaotong University 2018 N/A SuNAM Stainless steel (100 µm) Cu (15 µm) [10] Andong National University 2022 Clip [11] Andong National University 2019 Solder [13] Andong National University 2018 Solder [14] Andong National University 2019 N/A both manufacturers, irrespective of the method used to attach the voltage. We do not know whether the measurement conditions are identical across the studies in [10,11,13] from Andong National University. Therefore, drawing a clear conclusion about the clip's equivalence to the solder proves difficult.…”

Section: Discussionmentioning

confidence: 99%

“…The I c vs. tensile properties of REBCO tapes are typically measured via in-situ equipment capable of measuring the I c by the four-probe method and applying tensile force simultaneously. Numerous studies have reported the I c vs. tensile values of REBCO tapes with different specifications from various manufacturers [10][11][12][13][14][15][16][17][18][19]. During in-situ measurements, the voltage tap is attached to the REBCO tape through force application.…”

Section: Introductionmentioning

confidence: 99%

Novel two-step procedure for measuring I _c vs. tensile stress of commercial REBCO tape

Zhang,

Chen,

Wang

et al. 2023

Supercond. Sci. Technol.

3

0

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This paper presents a novel two-step procedure for measuring the critical current (Ic) properties as a function of tensile stress. The proposed method completely eliminates the possible negative effect of the voltage tap used during the tensile procedure, allowing the actual Ic irreversible degradation stress to be clearly determined. Six different commercial REBCO tapes from five manufacturers were tested. The Ic value does not degrade until the stress reaches the “inflection area” in the tensile curve, which corresponds to the most pronounced transformation step from elastic to plastic deformation. This allows easy estimation of the stress corresponding to Ic irreversible degradation by a simple and accurate cryogenic tensile curve instead of complicated in-situ Ic tensile measurement. A feasible composite-material tensile model is established to explain the phenomenon. In addition, fatigue measurements on a commercial REBCO tape from Shanghai Superconductor technology show that the tape can withstand 10,000 cycles under 580 MPa and over 5,000 cycles under 695 MPa, which also is consistent with the proposed composite-materials tensile model and is confirmed by the EBSD experiments on the Hastelloy substrate. This research provides better insight and tools for designing and fabricating extremely high-field magnets.

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Evaluation of Irreversible Strain/Stress Limits for Ic Degradation in Practical REBCO CC Tapes Under Uniaxial Tension

Cited by 17 publications

References 19 publications

Controllable rectification on the irreversible strain limit of 2G HTS coated conductors

Controllable rectification on the irreversible strain limit of 2G HTS coated conductors

Establishing a test procedure for evaluating the electromechanical properties of practical REBCO coated conductor tapes by the uniaxial tension test at 77 K

Novel two-step procedure for measuring I _c vs. tensile stress of commercial REBCO tape

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Evaluation of Irreversible Strain/Stress Limits for Ic Degradation in Practical REBCO CC Tapes Under Uniaxial Tension

Cited by 17 publications

References 19 publications

Controllable rectification on the irreversible strain limit of 2G HTS coated conductors

Controllable rectification on the irreversible strain limit of 2G HTS coated conductors

Establishing a test procedure for evaluating the electromechanical properties of practical REBCO coated conductor tapes by the uniaxial tension test at 77 K

Novel two-step procedure for measuring I c vs. tensile stress of commercial REBCO tape

Contact Info

Product

Resources

About

Novel two-step procedure for measuring I _c vs. tensile stress of commercial REBCO tape