Evaluation of Actual Delamination Strength of REBCO-Coated Conductors Based on the Weibull Analysis Considering Size Effect

Muto, Shigeo; Fujita, Shin; Akashi, Kazuya; Yoshida, Tomo; Iijima, Y.; Naoe, Kunihiro

doi:10.1109/tasc.2018.2805859

Cited by 16 publications

(8 citation statements)

References 12 publications

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“…The size effect means that the defects in the specimen become more varied as the test area increases. This is also corroborated by the fact that the m is as small as 1.9 in impregnation coil tests with a larger test area using the same conductor as the present study [15]. In the anvil tests, the reason for the difference in m depending on the temperature may be due to the effect of thermal shrinkage of copper and solder.…”

Section: Discussionsupporting

confidence: 85%

“…In this study, an average strength of 44.7 MPa was obtained for the anvil tests in the LN 2 temperature. However, the through-thickness strength is expected to approach zero as the bonding area increases because this and previous studies [15] show that the strength depends on the area. Therefore, in order to prevent mechanical damage, it is most important for superconducting application to design so that throughthickness compressive stress is applied to the CCs instead of tensile stress.…”

Section: Discussionmentioning

confidence: 79%

“…The REBCO CCs evaluated in this paper were mass-produced by IBAD/PLD process (FYSC-SCH05), which is similar to those used in our previous study [15]. The structure of the CC is shown in figure 1.…”

Section: Specification Of Rebco CCmentioning

confidence: 99%

“…There are many reports on longitudinal tensile fatigue properties through cyclic fatigue tests in terms of metal fatigue [9,10]. However, although an initial strength against a through-thickness tensile stress (delamination strength) has been evaluated by the pin-pull method [11,12], anvil method [13,14] and impregnated coil method [15], only few investigations on the fatigue under the through-thickness stress have been reported. In the longitudinal case, the metal fatigue is regarded to be dominant because a metal substrate and a cupper stabilizer of the REBCO CC are located in parallel with the superconducting ceramic layer, where the metals are responsible for most of the external forces.…”

Section: Introductionmentioning

confidence: 99%

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Fatigue behavior of REBCO coated conductors under through-thickness tensile stress

Muto¹,

Fujita²,

Sato³

et al. 2021

Supercond. Sci. Technol.

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Fujikura Ltd has developed production techniques of REBa2Cu3O X (REBCO, RE = rare earth) coated conductors (CCs) using large-area ion-beam-assisted-deposition and hot-wall type pulsed-laser-deposition. We have provided high-performance REBCO CCs with long length and high homogeneity of critical current. The CCs are required to maintain their superconducting properties under mechanical stresses for a long-term. Therefore, it is important to evaluate the fatigue properties of the CCs. Although there are many investigations on cyclic tensile fatigue in the longitudinal direction of the CCs, few studies on fatigue properties in the through-thickness direction have been reported. In the case of the through-thickness stress, i.e. delamination stress, the stress is applied to the REBCO ceramic layer without substrate reinforcement, static fatigue fracture may occur by subcritical crack growth peculiar to ceramics. In this work, we carried out dynamic fatigue tests under delamination stresses at room temperature (RT) and liquid nitrogen (LN2) temperature 77 K to determine the fatigue coefficient N characterizing the static fatigue. As a result, we found that the N-value was relatively low (N ∼ 20) at RT, while the N-value was extremely high (N ∼ 150) at LN2 temperature. This result shows that the crack growth of the REBCO layer under the through-thickness tensile stress is extremely slow at low temperatures as well as that reported for bulk ceramics such as SiO2 glass. Therefore, it is expected that the static fatigue in the through-thickness direction of REBCO CC hardly occurs at low temperatures.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 79%

Section: Specification Of Rebco CCmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fatigue behavior of REBCO coated conductors under through-thickness tensile stress

Muto¹,

Fujita²,

Sato³

et al. 2021

Supercond. Sci. Technol.

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“…For a long time, most Chinese construction units have used traditional building materials such as cement, concrete, glass, and ceramics (Marangoni et al, 2017). Although such materials have good durability and high environmental adaptability, most of these materials are non-renewable resources from the perspective of sustainable development (Muto et al, 2018). Excessive use of this type of material not only has a serious impact on the ecological environment, but also may cause China's overall ecological environment to decline year by year (Povarov 2016).…”

Section: Introductionmentioning

confidence: 99%

Insulation effect evaluation model of green building materials under ecological environment

2020

Issue 4

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<p>Green building materials are an important material basis for promoting the development of green buildings, and also the foundation of building energy conservation. In view of this, an insulation effect evaluation model of green building materials is constructed. The outer wall temperature index, the equivalent thermal resistance index, the inner surface maximum temperature and the thermal inertia index are used to characterize the insulation effect of the green building materials. According to the insulation effect evaluation principle of green building materials, the outer surface and inner surface temperature deviation curves and its’ fitting curves are made. The integral area between the fitting curve and the standard line is the temperature factor. The temperature factor can be used as an evaluation parameter for the insulation effect of green building materials in a fixed temperature range. It can characterize the average insulation effect of green building materials under a certain temperature range and comprehensive evaluation of different characterization indicators. The greater the temperature factor value is, the better the insulation effect is. The experimental results show that the model can accurately reflect the overall insulation effect of green building materials under the influence of various indicators in a certain temperature range, and the evaluation accuracy is high.</p>

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Correction Factor for Unbiased Estimation of Weibull Modulus by the Linear Least Squares Method

Jia

Nadarajah

2019

Metall Mater Trans A

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Evaluation of Actual Delamination Strength of REBCO-Coated Conductors Based on the Weibull Analysis Considering Size Effect

Cited by 16 publications

References 12 publications

Fatigue behavior of REBCO coated conductors under through-thickness tensile stress

Fatigue behavior of REBCO coated conductors under through-thickness tensile stress

Insulation effect evaluation model of green building materials under ecological environment

Correction Factor for Unbiased Estimation of Weibull Modulus by the Linear Least Squares Method

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