Numerical simulation of dynamic fracture behavior in bulk superconductors with an electromagnetic-thermal model

Ru, Yanyun; Yong, Huadong; Zhou, Youhe

doi:10.1088/1361-6668/ab0e93

Cited by 18 publications

(10 citation statements)

References 57 publications

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“…Naturally, the modelling of HTS machines becomes very complicated and time consuming, no matter which type of formulation is chosen. In order to mitigate the simulation com-plexity, most of the researchers have only focused on the superconducting parts in electric machines and choose 2D models to study the cross section of HTS coils, stacks of tapes, and bulks [84][85][86][87][88][89][90][91][92][93][94][95]. However, the electromagnetic environment inside electric machines is quite complex, and is also decided by non-superconducting parts, such as iron cores and iron slotted structures.…”

Section: Modelling Methodsmentioning

confidence: 99%

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

Zhang¹,

Wen²,

Grilli

et al. 2021

Energies

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Superconductor technology has recently attracted increasing attention in power-generation- and electrical-propulsion-related domains, as it provides a solution to the limited power density seen by the core component, electrical machines. Superconducting machines, characterized by both high power density and high efficiency, can effectively reduce the size and mass compared to conventional machine designs. This opens the way to large-scale purely electrical applications, e.g., all-electrical aircrafts. The alternating current (AC) loss of superconductors caused by time-varying transport currents or magnetic fields (or both) has impaired the efficiency and reliability of superconducting machines, bringing severe challenges to the cryogenic systems, too. Although much research has been conducted in terms of the qualitative and quantitative analysis of AC loss and its reduction methods, AC loss remains a crucial problem for the design of highly efficient superconducting machines, especially for those operating at high speeds for future aviation. Given that a critical review on the research advancement regarding the AC loss of superconductors has not been reported during the last dozen years, especially combined with electrical machines, this paper aims to clarify its research status and provide a useful reference for researchers working on superconducting machines. The adopted superconducting materials, analytical formulae, modelling methods, measurement approaches, as well as reduction techniques for AC loss of low-temperature superconductors (LTSs) and high-temperature superconductors (HTSs) in both low- and high-frequency fields have been systematically analyzed and summarized. Based on the authors’ previous research on the AC loss characteristics of HTS coated conductors (CCs), stacks, and coils at high frequencies, the challenges for the existing AC loss quantification methods have been elucidated, and multiple suggestions with respect to the AC loss reduction in superconducting machines have been put forward. This article systematically reviews the qualitative and quantitative analysis methods of AC loss as well as its reduction techniques in superconductors applied to electrical machines for the first time. It is believed to help deepen the understanding of AC loss and deliver a helpful guideline for the future development of superconducting machines and applied superconductivity.

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Section: Modelling Methodsmentioning

confidence: 99%

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

Zhang¹,

Wen²,

Grilli

et al. 2021

Energies

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“…The magnetic-thermal characteristics and mechanical stress of an REBCO superconducting bulk material with an inhomogeneous critical current density during PFM were analyzed by Wu et al [62] and Hirano et al [63]. In addition, cracks in the bulk can propagate under complicated electromagnetic and mechanical loadings [64][65][66]. The coupled magnetic-thermal model and phase-field fracture model were proposed to simulate the flux jump and mechanical failure behaviors of bulk superconductors during PFM [67].…”

Section: Introductionmentioning

confidence: 99%

Flux jump and mechanical response in inhomogeneous high-temperature superconductor under the pulsed-field magnetization

Wang,

Wu,

Yong

2023

Supercond. Sci. Technol.

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The high-temperature bulk superconductors with high critical current density are brittle, and can be damaged by large Lorentz forces and thermal stress during magnetization. Several studies have reported the failure of bulk superconductors during flux jumps. In this study, we analyzed the magnetization characteristics and mechanical response of the HTS bulk with inhomogeneous current density along the c-axis. The numerical simulation was consistent with the experimental results presented in the reference. Moreover, a flux jump occurred near the area of the pre-arrangement flux during the second pulsed field magnetization. The maximum temperature is lower than the critical temperature during the flux jump. In the mechanical analysis, the flux jump led to an abrupt change in the maximum stress of the bulk, and the maximum radial stress was significantly higher than the maximum hoop stress during the flux jump. The maximum radial stress increased with decreasing ambient temperature during the flux jump, and the maximum stress area was always near the seeded plane. Subsequently, the magnetization characteristics and mechanical response were studied for different locations of the seeded surface, two concentric superconducting bulks, and non-uniform fields.

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“…Especially, the stresses can be enhanced more markedly during a flux jump process as thermal stress is introduced. Up to now a great deal of research has been undertaken into the edge and central crack problems induced by the electromagnetic force for bulk SCs [29][30][31][32][33][34][35][36]. For example, Zhou and Yong analyzed the fracture behavior of a long rectangular slab-shaped SC in parallel magnetic fields on the assumption that the crack was small enough so that its influence on the critical current was negligible [29].…”

Section: Introductionmentioning

confidence: 99%

Thermomagnetic instability and accompanied stress intensity factor jumps in type-II superconducting bulks under various magnetization processes

Huang¹,

Song²,

Wang³

et al. 2022

Supercond. Sci. Technol.

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For type-II superconducting bulks used as trapped-field magnets, the thermomagnetic instability, manifested as flux jumps and temperature spikes, frequently takes place, resulting in a large amount of energy dissipation in a short time and further the crack problem due to electromagnetic and thermal stresses. In this paper, based on the magnetic and heat diffusion equations and fracture theory, we develop a thermal-magnetic-mechanical coupling model to analyze the flux-jump and fracture behaviors in bulk samples of BiSrCaCuO under various magnetization processes. This model has an important advantage that the simulation domain can be restricted to the sample itself, without having to consider the air region around it, and its reliability is verified by the existing experimental and numerical results. The effects of the sample size, the ambient temperature, and the sweep rate, direction, and uniformity of the external magnetic field on the flux jumps, and Mode I and Mode II stress intensity factors are fully analyzed under different cooling conditions. It is found that as ambient temperature or field inclined angle increases or field sweep rate decreases, the first flux-jump field presents a trend of monotonically increasing for zero-field-cooling magnetization but it has an opposite trend for field-cooling magnetization. The flux jump can lead to the jump of temperature, electromagnetic force, and stress intensity factor. In addition, the sensitivity of flux-jump and fracture behaviors to different parameters and the influence of flux jump on the demagnetization behavior under crossed magnetic fields are discussed. We also find the levitation force jumping phenomenon when the bulk sample is magnetized in a nonuniform magnetic field. From the results obtained, we provide some general guidelines on how the system parameters of superconducting bulk magnets could be chosen to improve the thermal-magnetic-mechanical stability.

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Numerical simulation of dynamic fracture behavior in bulk superconductors with an electromagnetic-thermal model

Cited by 18 publications

References 57 publications

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

Flux jump and mechanical response in inhomogeneous high-temperature superconductor under the pulsed-field magnetization

Thermomagnetic instability and accompanied stress intensity factor jumps in type-II superconducting bulks under various magnetization processes

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