Measurement of Shear Delamination Strength of REBCO Coated Conductors

Gao, Peifeng; Geng, Xiang; Man, Guian; Wang, Xingzhe

doi:10.1109/tasc.2021.3136831

Cited by 10 publications

(5 citation statements)

References 39 publications

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“…Experimental study of REBCO CC tapes and windings have indicated that the conductor is debonded through 'mixedmode' delamination [13,16,21,30], meaning delamination appears at interfaces or fractures in brittle layers. Calculation results based on DEM indicated that delamination of a multilayer REBCO CC tape can begin at any of the interfaces or simultaneously at more than one interface [24].…”

Section: D Axisymmetric Mixed-mode Delamination Modelmentioning

confidence: 99%

“…The weak delamination strength of REBCO CC tapes was investigated experimentally. The transverse tensile strength varied from 2 to 110 MPa [10][11][12][13][14][15][16] and the shear delamination strength varied from 10 to 60 MPa [20,21]. In this simulation model, the cohesive strengths in normal and shear directions were selected as σ 0 n = σ 0 s = 10 MPa, which are in the range of the experimental results.…”

Section: Geometry and Materials Propertiesmentioning

confidence: 99%

“…delamination strength) of REBCO CC tapes critically threatens the structural and superconducting stability of the facilities in which they are used. The low delamination strength of REBCO CC tapes has been revealed by several methods, including anvil tensile tests [10][11][12][13][14][15][16], peel tests [17,18], cleavage tests [19], and shear tests [20,21]. Anvil tension tensile testing revealed that the transverse delamination strength varied from 2 to 110 MPa [10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…Simulation results indicated that the delamination strength was affected by intrinsic defects in the CC tapes and non-interfacial elastic-plastic deformation induced by anvil tension. Subsequently, based on uniaxial tensile tests, a novel method was developed to measure the interfacial strength in the transverse tensile and shear directions of REBCO CC tapes [16,21], which can eliminate the scatter of experimental data by reducing the effect of intrinsic defects in test samples, removing the non-interface elastic-plastic deformation caused by anvil tension, and avoiding the effects of welding. A systematic study on the residual stresses and delamination behaviour in multilayer REBCO CC based on the displacement-energy model (DEM) was reported by Mbam and Gou [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

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Delamination model of an epoxy-impregnated REBCO superconducting pancake winding

Gao

Pan

2022

Supercond. Sci. Technol.

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Rare-earth barium copper oxide (REBCO) coated conductor (CC) tapes are promising for high-energy and high-field applications. In epoxy-impregnated REBCO superconducting windings, during the cooling process, the delamination induced by thermal mismatch stress significantly threatens stable operation due to the weak c-axial strength of REBCO CC tapes. In this study, a two-dimensional axisymmetric multilayer delamination finite element model with main layers of REBCO CC tapes and insulation materials was developed based on the bilinear cohesive zone model. Based on the proposed model, the stress distribution and delamination properties of an epoxy-impregnated REBCO winding induced during the cooling process were investigated. Furthermore, the effects on the structural configuration on the delamination and optimisation schemes of fabrication are discussed. The model results indicate that during the cooling process of the REBCO winding, when the radial tensile stress induced by the thermal mismatch stress is greater than the delamination strength, interface cracking will occur. Interface failure occurs in regions containing several turns of coils and not just a single-turn coil. Our analyses indicate that structural failure caused by delamination depends on the radius ratio of the outer to the inner winding, where a small radius ratio is preferred to reduce the risk of delamination. An excessive radius ratio can result in multiple delamination failures during the cooling process. The optimisation scheme, which divides the winding into several sub-windings with a consistently small radius ratio, is an effective method for mitigating the risk of delamination failure, which is consistent with available experimental results. Additionally, by reducing the thermal expansion coefficient of the epoxy resin, the risk of delamination failure during cooling can be significantly reduced. For the winding structure considered in this study, if the coefficient of thermal expansion of the epoxy resin is reduced to 5 (×10^6 K-1), then delamination failure caused by thermal mismatch will be eliminated. Our model results are consistent with those of several valuable experimental phenomena and numerical calculated in the literature.

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Section: D Axisymmetric Mixed-mode Delamination Modelmentioning

confidence: 99%

Section: Geometry and Materials Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Delamination model of an epoxy-impregnated REBCO superconducting pancake winding

Gao

Pan

2022

Supercond. Sci. Technol.

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“…The critical current of the magnet will drop severely when the stress exceeds the corresponding yield stress [ 31 ]. Furthermore, a REBCO tape has a high axial tensile strength, but its interfacial strength is as low as 2–100 MPa [ 32 , 33 , 34 , 35 ], and its cleavage strength and peel strength are less than 1 MPa [ 36 ]. Therefore, delamination between the constituent layers may occur if the stress exceeds the corresponding critical value.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on Mechanical Responses during Quench Protection in High-Temperature Superconducting Coils

Jiao

Guan

2023

Materials

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In this paper, mechanical responses and electro-thermal characteristics of a rare earth barium copper oxide (REBCO) high-temperature superconducting (HTS) insulated pancake coil during the quenching process are investigated through finite element modeling (FEM). Firstly, a two-dimensional axisymmetric electro–magneto–thermal–mechanical FEM model with real dimensions is developed. Based on the FEM model, a systematic study on the effects of the time taken to trigger the system dump, background magnetic field, material properties of constituent layers, and coil size on quench behaviors of an HTS-insulated pancake coil is implemented. The variations in the temperature, current, and stress–strain in the REBCO pancake coil are studied. The results indicate that an increase in the time taken to trigger the system dump can increase the peak temperature of the hot spot but has no influence on the dissipation velocity. An apparent slope change of the radial strain rate is observed when the quench occurs regardless of the background field. During quench protection, the radial stress and strain reach their maximum values and then decrease as the temperature decreases. The axial background magnetic field has a significant influence on the radial stress. Measures to reduce peak stress and strain are also discussed, which indicates that increasing the thermal conductivity of the insulation layer, copper thickness, and inner coil radius can effectively reduce the radial stress and strain.

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Critical current degradation in an epoxy-impregnated rare-earth Ba2Cu3O7−x coated conductor caused by damage during a quench

Liu,

Yong,

Zhou

2024

Appl. Math. Mech.-Engl. Ed.

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Measurement of Shear Delamination Strength of REBCO Coated Conductors

Cited by 10 publications

References 39 publications

Delamination model of an epoxy-impregnated REBCO superconducting pancake winding

Delamination model of an epoxy-impregnated REBCO superconducting pancake winding

Numerical Study on Mechanical Responses during Quench Protection in High-Temperature Superconducting Coils

Critical current degradation in an epoxy-impregnated rare-earth Ba2Cu3O7−x coated conductor caused by damage during a quench

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