Elastoplastic mechanical behavior of high-field magnet of REBCO high temperature superconducting composite tape under extreme environment

Due to the high isotropy and low AC losses, the multi-layer conductor on Round Core (CORC) cable is a good candidate for high field magnets, such as central solenoid magnets in fusion. Considering the difficulty in experimental measurement, numerical model is an effective way to illustrate the electromagnetic characteristics of the multi-layer CORC cable and provide further insights into its working performance. In this work, A 3D finite element model based on H formulation is proposed to simulate a CORC cable with as many as 18 layers considering electromagnetic coupling. The validity of the model has been verified by experimental results. Based on the proposed model, the DC transport current distribution characteristics and charge-discharge loss characteristics of multi-layer CORC cables wound in the same and opposite winding directions are investigated respectively. This work can provide an important reference for the design of multi-layer CORC cables for high-current or high-field application.

Section: Introductionmentioning

confidence: 99%

Numerical study on the electromagnetic characteristics of multi-layer CORC cables

Li,

Yang,

et al. 2024

“…With the development of laser scribing technology, the probability of defects appearing during fabricating long-distance REBCO tapes has become smaller [16,17]. However, it is impossible to guarantee absolute stability during tape processing, coil winding, and operation, resulting in the non-uniformity of the local critical current density [18]. In addition to multi-filament technologies, mechanical cutting is another narrowing method.…”

Section: Introductionmentioning

confidence: 99%

Non-uniform critical current and stacking effect remedy for multi-filament REBCO tapes with potential defects

Cai,

Wang,

Hao

et al. 2024

The high aspect ratio of REBCO tapes has a significant impact on several characteristics in high-temperature superconducting (HTS) applications, like critical current and AC loss. Narrow filamentary technology can effectively reduce the impact of magnetic field dependence and enhance the electromagnetic performance of REBCO tapes. However, the existing methods are constrained by the trade-off between the narrow degree of REBCO filaments and high current capacity. Meanwhile, when processing REBCO tapes for large-scale magnets, there is a great possibility that local defects are lurking. A striated narrow-stacked structure is proposed based on the existing narrowing methods to address these challenges. To verify the validity of this structure, it is imperative to explore the non-uniform critical current and stacking effect on performance for multi-filament REBCO tapes with potential defects. This article introduces a magnetic extended network (MEN) model to analyze the electrical characteristics of striated narrow-stacked structures with different types of potential defects. Then, by coupling with a 3-D finite element method (FEM) electromagnetic module, the calculation results of the MEN model are visualized and used to analyze the electromagnetic characteristics including current sharing mechanism, magnetic field distribution, and critical current compensation due to stacking effect. It is found that stack structures successfully provide the performance remedy for multi-filament REBCO tapes with potential defects. This study aims to promote the narrowing improvement of REBCO tapes in high-field magnets and high-current applications.

A concurrent multiscale model of stress-induced delamination behaviours of epoxy-impregnated rare-earth barium copper oxide superconducting pancake winding

Guo,

Gao,

Chen

et al. 2024

Rare-earth barium copper oxide (REBCO) coated conductor (CC) tapes are promising for high-energy and high-electromagnetic field applications. In epoxy-impregnated REBCO superconducting coils, due to the weak c-axial strength of REBCO CC tapes, delamination induced by thermal-mismatch stress and Lorentz force significantly threatens stable operation. The commonly used numerical modelling methods mainly include homogenized model and refined model. The former can realize the efficient calculation of the overall physical field but lose the local details including interfacial delamination behaviour, while the latter can realize the refined calculation but cost massive calculation. In this study, combining with bilinear cohesive zone model (CZM), a two-dimensional axisymmetric concurrent multiscale model was developed to balance the efficiency-accuracy trade-off for numerically investigating the mechanical properties and interface failure behaviours of REBCO superconducting coils under cryogenics and high-electromagnetic field. In the presented model, the homogenized superconducting coil was firstly constructed based on composites homogenized approach to estimate the electromagnetic-thermal-mechanical properties at macro scale. Then, the ‘dangerous regions’ in the macro scale was recognized based on quadratic failure criterion and replaced with a refined model considering delamination failure defined by CZM. Finally, the two scales are linked through the coupling interface. The accuracy and efficiency of the concurrent multiscale model were validated by refined model for the cases of delamination behaviour during cooling and excitation.