Bending Strain Effects on the Critical Current in Cu and Cu–Nb–Stabilized YBCO-Coated Conductor Tape

Polikarpova, M.; Lukyanov, Pavel; Abdyukhanov, I. M.; Pantsyrny, V.; Vorobyeva, A. E.; Khlebova, N. E.; Sudyev, S V; Shikov, A.K.; Guryev, Valentin

doi:10.1109/tasc.2013.2286739

Cited by 13 publications

(7 citation statements)

References 16 publications

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“…Taking this study as an example, the normalized critical current I c /I c0 gradually decreased from 1.000 to 0.925 as the bending radius decreased from infinity to 4.75 mm, whereas rapidly and irreversibly decreased from 0.925 to 0.820 as the bending radius decreased within a small increment of bending deformation from 4.75 mm to 3.5 mm. The irreversible bending curvature of the bending radius of 4.75 mm was 0.21 mm −1 , which was in the range from 0.20 to 0.26 mm −1 , indicating that the calculated initial radius of irreversible degradation of I c was consistent with the experimental results [82]. Under compressive bending loads, the corresponding values of I c /I c0 decreased from 1.000 to 0.878 as the bending radius decreased from infinity to 3.5 mm.…”

Section: Bending Loadingsupporting

confidence: 78%

“…In this paper, the I c degradation behavior of REBCO CC tapes under bending loads was predicted using the phenomenological model (14) with the model parameters determined by the axial tensile strain dependence of I c . A comparison of the normalized critical current I c /I c0 degradation behavior of REBCO CC tapes under bending loads at 77 K between the calculated results in this study and the experimental results [81,82] is shown in figure 11. The calculated results are based on the non-uniform internal strain in the REBCO films obtained by FEM and the internal strain dependence of I c model.…”

Section: Bending Loadingmentioning

confidence: 86%

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Analysis of mechanical behavior and electromechanical properties of REBCO-coated conductor tapes under combined bending-tension loads using numerical methods

Pan¹,

Gao²

2023

Supercond. Sci. Technol.

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Rare-earth barium copper oxide (REBCO) high-temperature superconducting (HTS) -coated conductor (CC) tapes are potential conductors for high-field magnets. In an operating high-field magnet, REBCO CC tapes are bent into coils and simultaneously subjected to hoop electromagnetic forces. Under these combined bending-tension loads, the critical current (Ic) of the REBCO CC tapes is at risk of irreversible degradation. Therefore, investigating the mechanical behavior and electromechanical properties of REBCO CC tapes under combined bending-tension loads is necessary. In this study, the mechanical behavior of REBCO CC tapes was analyzed using a finite element model (FEM). First, in the fabrication-cooling process of REBCO CC tapes, the thermal residual stress/strain accumulated in the constituent layers was analyzed. Then, considering the thermal residual stress/strain as the initial stress-strain state, the mechanical behavior of REBCO CC tapes under various mechanical loads, such as axial tension, bending, and combined bending‑tension at 77 K, was analyzed. Furthermore, a phenomenological model of the internal strain in the REBCO films dependence of Ic was developed for analyzing the electromechanical properties of REBCO CC tapes under combined bending-tension loads at 77 K. Calculated results showed that the compressive thermal residual strain in REBCO films at 77 K was -0.25%, and the internal strain in the REBCO films corresponding to the irreversible degradation of Ic was 0.45% under axial tension loads, which was verified by experimental results. Under bending and combined bending-tension loads, the distribution of the internal strain in the REBCO films along the width direction was non-uniform owing to the Poisson effect, and the onset of the irreversible degradation of Ic occurred at the outer edge of the REBCO films. The phenomenological model was experimentally verified to be effective in Ic degradation behavior prediction under combined bending-tension loads, and model predictions based on the FEM results indicated that the electromechanical properties were significantly influenced by the bending modes (tensile bending or compressive bending) of the REBCO CC tapes.

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Section: Bending Loadingsupporting

confidence: 78%

Section: Bending Loadingmentioning

confidence: 86%

Analysis of mechanical behavior and electromechanical properties of REBCO-coated conductor tapes under combined bending-tension loads using numerical methods

Pan¹,

Gao²

2023

Supercond. Sci. Technol.

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“…The change in the sheet resistance for the ITO sample is shown in Figure 3(b) and is plotted as a function of the inverse of the radius because the strain is mostly proportional to the inverse of the bending radius. 13 The sheet resistance of the ITO sample for the case with 1.00 cm of bending (50 /sq) was not significantly different from that of other samples (e.g., the controlled case at 10 /sq), as shown in Figure 3(b). However, the sheet resistance drastically increased to 900 /sq for 0.50 cm of bending and 200 /sq for 0.75 cm, which is 90 (or 20) times greater than that of the control sample.…”

Section: Methodsmentioning

confidence: 78%

Effects of Bending Radii on the Characteristics of Flexible Organic Solar Cells Investigated by Impedance Analysis

Kim¹,

Ye²,

Won³

et al. 2016

j nanosci nanotechnol

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Flexible organic solar cells (OSCs) were fabricated on an indium-tin-oxide (ITO)/poly(ethylene terephthalate) (PET) substrate and were subjected to bending tests with various bending radii. We observed that the photovoltaic properties of the OSCs precipitously deteriorated at a bending radius ≤ 0.75 cm. In order to investigate the effects of the bending test, the changes in the surface morphology and the sheet resistance of the ITO-coated PET samples were investigated, and the photovoltaic properties of bent and unbent OSCs were evaluated. Thereafter, equivalent circuits for the OSCs were assumed and the change in their parameters, such as resistance and capacitance, was observed.

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“…For the applications of REBCO tapes, several key properties are very important, such as the critical current (I c ), yeild stress and electromechanical behaviors. Extensive work has been done to understand the behaviors of REBCO tapes and coils under different conditions, including the change of I c under different external forces and deformations [7][8][9][10][11][12][13][14][15][16], the current redistribution [17], and the behavior of current under external fields [18][19][20]. Studies showed that the I c of REBCO tapes was influenced by intrinsic strain induced by external forces or deformations [7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…Extensive work has been done to understand the behaviors of REBCO tapes and coils under different conditions, including the change of I c under different external forces and deformations [7][8][9][10][11][12][13][14][15][16], the current redistribution [17], and the behavior of current under external fields [18][19][20]. Studies showed that the I c of REBCO tapes was influenced by intrinsic strain induced by external forces or deformations [7][8][9][10][11][12][13][14][15]. The I c of REBCO tapes initially decreased slowly with the increase in strain, and then decayed rapidly when the strain reached a certain critical value.…”

Section: Introductionmentioning

confidence: 99%

Typical electrical, mechanical, electromechanical characteristics of copper-encapsulated REBCO tapes after processing in temperature under 250 °C

Pan

Yu³

et al. 2023

Supercond. Sci. Technol.

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Heat treatments are inevitable not only in the production of rare earth barium copper oxide (REBCO) tapes, but also in their post-processing for applications, typically, in soldering and epoxy/wax impregnation during the fabrication of REBCO coils. In general, the heat treatment of REBCO tapes should be carried out at lower temperature for a shorter time, but the specific safe boundary of heat-treatment temperature and time for REBCO tapes is still unknown. Therefore, a comprehensive study on the typical electrical, mechanical, and electromechanical characteristics of REBCO tapes after heat treatments under temperature of 250 ℃ is necessary. This work focus on the copper-encapsulated REBCO tapes, which are more robust (while with much lower engineering current density) to be processed in application systems than the tapes without encapsulation. The critical current degradation, stress-strain characteristic, and electromechanical properties of REBCO tapes were measured after heat treatments at different temperatures in argon and oxygen atmosphere. A 2D finite element analysis model was established for detailed stress/train analyzes under tension and bending based on the analysis of residual stress/strain. The results indicate that the critical current of the copper-encapsulated REBCO tapes decreases with increasing heat-treatment temperature and dwell time, and is of no evident relation to atmosphere. In addition, increased temperature of heat treatment leads to an obvious decrease in the yield strength and critical tensile stress. This effect is mainly attributed to the degradation of mechanical properties of the encapsulated copper layer, which is demonstrated by the combination of our finite element simulation and the experiments results. Interestingly, the change in the critical bending radius due to heat treatments was slight, because the bending axial strain of the REBCO layer remained almost unchanged after heating. It is also worthy to note that all the properties tested in this study were irrelevant to the external oxygen partial pressure during the heating process. As a practical conclusion for the application systems, an upper and atmosphere-irrelevant limit of processing temperature of 130 or 150 ℃ (2 h dwell time) was proposed for copper-encapsulated REBCO tapes, under which the critical current, yield strength, critical tensile stress/strain and critical bending radius of the copper-encapsulated REBCO tapes decay by < 1% or 3%, respectively.

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Bending Strain Effects on the Critical Current in Cu and Cu–Nb–Stabilized YBCO-Coated Conductor Tape

Cited by 13 publications

References 16 publications

Analysis of mechanical behavior and electromechanical properties of REBCO-coated conductor tapes under combined bending-tension loads using numerical methods

Analysis of mechanical behavior and electromechanical properties of REBCO-coated conductor tapes under combined bending-tension loads using numerical methods

Effects of Bending Radii on the Characteristics of Flexible Organic Solar Cells Investigated by Impedance Analysis

Typical electrical, mechanical, electromechanical characteristics of copper-encapsulated REBCO tapes after processing in temperature under 250 °C

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