Delamination Characteristics of Single Layer and Stacked HTS Coated Conductor for Conduction Cooling Application

Park, Heecheol; Jung, Hwanjun; Kim, Seokho; Park, Minwon; Lee, Sang-Jin; Ha, Hong-Soo; Moon, Seung‐Hyun; Jeong, Sangkwon

doi:10.1109/tasc.2012.2236142

Cited by 15 publications

(3 citation statements)

References 12 publications

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“…Based on the symmetric properties of HTS pancake windings, 2D axisymmetric models are widely recognised for their simplicity and accuracy in analytical analysis and numerical calculation [33][34][35][36][37][38][39][41][42][43][44][45][46][47][48]. In particular, axisymmetric models have been effectively used to predict the stress distribution and delamination behaviour of epoxy-impregnated HTS windings [34-39, 41, 47, 48].…”

Section: Numerical Modellingmentioning

confidence: 99%

“…In the edge region of the winding, the radial stress is partially absorbed by soft materials such as copper stabiliser, insulation materials, and epoxy resin. Radial compressive stress reduces the risk of delamination for associated with the larger CTE of soft materials [33,41]. Therefore, when there are no defects in the ideal state, interface cracking first appears inside the conductor, rather than at the edge.…”

Section: Stress Distributionmentioning

confidence: 99%

“…However, these methods negatively affect the structural stability of the winding and cause the coil to move. FE numerical investigations have been conducted to study the stress and delamination properties of epoxy-impregnated REBCO superconducting windings further [33][34][35][36][37][38][39][40]. The 2D axisymmetric FE model with equivalent homogeneous winding properties has been validated as an efficient calculation method for stress distribution analysis in epoxy-impregnated REBCO windings [35][36][37][38].…”

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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