Effect of preloading on the relaxation of the levitation force in bulk Y–Ba–Cu–O superconductors

Komano, Yasuo; Ito, Eri; Sawa, Kôichiro; Iwasa, Y.; Ichihara, T.; Sakai, Naomichi; Hirabayashi, I.; Murakami, Masato

doi:10.1016/j.physc.2005.02.155

Cited by 10 publications

(3 citation statements)

References 6 publications

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“…Since the discovery of the high-temperature superconductors (HTSs), magnetic levitation based on the interaction between a permanent magnet and a high-T c superconductor has been widely used in making frictionless bearings [1], in flywheel energy storage systems [2,3], and in maglev [4,5]. The time stability of these systems is very important and has been studied by many researchers [6][7][8][9][10]. Riise et al [6] reported the levitation force logarithmic decay with time in the case of field-cooling condition.…”

Section: Introductionmentioning

confidence: 99%

“…Luo et al [7] investigated the reduction of levitation force decay in high-temperature superconducting bearings and the hysteresis hardening effect was found. In order to reduce the levitation force relaxation, preloading [8,9] and reverse magnet motion [10] have been presented and recognized experimentally and theoretically, but these methods are effective in reducing the relaxation of the levitation force, while the effective levitation force is also depressed. Zhang et al [11] reported a new method to reduce the relaxation of the levitation force based on the hysteresis characteristic of HTSs.…”

Section: Introductionmentioning

confidence: 99%

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Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system

Zhang

Zhou

et al. 2009

Supercond. Sci. Technol.

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We present an experimental study of the relaxation of vertical and horizontal force components in an unsymmetrical high-temperature superconducting levitation system, with different initial cooling processes, after fixing the levitated body statically in a given position. It was found that the values of the relaxation measurements of the levitation force and lateral force remained constant or increased with time after vertical and horizontal traverses. The phenomenon has been theoretically described based on the Bean model and the thermally activated flux creep theory. The criterion developed in the present work is considered to be suitable for providing qualitative predictions of the relaxation properties in the levitation force and lateral force.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system

Zhang

Zhou

et al. 2009

Supercond. Sci. Technol.

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“…(i) Vertical motion stage: the 3D SC must be vertically moved to its working position before the maglev system can operate. In general, three strategies are adopted to magnetize the SC [34][35][36]: the zero-field cooling (ZFC) strategy is implemented by first cooling the SC at a large height above the center of the guideway, where the magnetic field of PMs can be neglected ZFC, and then moving the SC to its working height h 0 . The field cooling (FC) strategy is carried out by first cooling the SC at a height h FC above the center of the guideway FC, and then moving the SC to its working height h 0 .…”

Section: D Electromagnetic-thermal-mechanical Coupling Modelmentioning

confidence: 99%

Nonlinear dynamics of 3D superconducting maglevs with six degrees of freedom: dependence on magnetization strategy and disturbance type

Huang,

Diao,

Liu

et al. 2023

Supercond. Sci. Technol.

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Based on the heat diffusion equation, Maxwell’s equations, and translational and rotational dynamic equations, we establish and theoretically validate an electromagnetic-thermal-mechanical coupling model to analyze the levitation performance during normal operation and the nonlinear dynamic behavior under disturbance for 3D maglev systems composed of a six-degree-of-freedom bulk superconductor (SC) and a Halbach-type guideway of permanent magnets (PMs) with different magnetization strategies and different types of disturbances, as well as the change rules of magnetic force and torque during translational or rotational cycle movement. In order to ensure the system security, we propose a generalized electromagnetic restoring force model to theoretically analyze the stability of the SC moving along the directions of various degrees of freedom. The results show that after being disturbed, the SC vibrates along the direction of each degree of freedom, and the vibration center, i.e. equilibrium position, will drift along each vibration direction. With time increasing, the equilibrium position will appear periodically on both sides of the working position. Compared to zero-field cooling magnetization, field cooling magnetization enables the SC to trap more flux in its interior to alleviate the drift phenomenon and reduce the energy loss. This advantage can be further enhanced by adding an extra step of preloading treatment. For the lateral motion, the system has one stable focus point and two unstable saddle points. Whether the system at these saddle points is stable depends on the direction of disturbance-induced velocity. For the rotational motion, the system has only one stable focus point, which means that regardless of the type of disturbance, the SC will finally come back to its stable equilibrium position. Besides, the stability is related to the axis around which the SC rotates, and rotating around the longitudinal axis is more likely to generate larger magnetic force, torque and local temperature rise. Either field cooling magnetization or preloading treatment can effectively improve system stability.

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Modeling of Vibration and Drift Behaviors Triggered by Environmental Factors in a Superconducting Maglev with Thermal-Electromagnetic Interaction

2021

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Effect of preloading on the relaxation of the levitation force in bulk Y–Ba–Cu–O superconductors

Cited by 10 publications

References 6 publications

Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system

Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system

Nonlinear dynamics of 3D superconducting maglevs with six degrees of freedom: dependence on magnetization strategy and disturbance type

Modeling of Vibration and Drift Behaviors Triggered by Environmental Factors in a Superconducting Maglev with Thermal-Electromagnetic Interaction

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