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Electromagnetic strain measurements and two-directional mechanical stress estimation for a REBaCuO ring bulk reinforced by a metal ring during field-cooled magnetization

Accepted version
Peer-reviewed

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Article

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Abstract

jats:titleAbstract</jats:title> jats:pIn this paper, simultaneous measurements of the electromagnetic strains along both the circumferential (jats:italicθ</jats:italic>) and radial (jats:italicr</jats:italic>) directions are reported for a large single-grain EuBaCuO ring bulk reinforced by an Al alloy ring during field-cooled magnetization (FCM) from 5 T at 50 K using several strain gauges adhered to the surface. To verify the experimental results and to understand the complex stress–strain behavior, mechanical analyses were carried out using a three-dimensional finite element model that closely represents the experimental setup. The simulation results of the electromagnetic strains along both directions showed excellent qualitative and quantitative agreement with the experimental ones. These results strongly suggest that the numerical model must include the exact same structure (size, shape and materials) of the mechanical support structure as the experimental setup in order to reproduce the experimental results both qualitatively as well as quantitatively. This also explains our previous research (SuST 2019 jats:bold32</jats:bold> 015007), where the measured circumferential strains were about 50% smaller those in the numerical simulation. Furthermore, the electromagnetic stresses along both directions during the FCM process are estimated from the obtained experimental strains. As a result, the estimated stresses were fairly consistent with those obtained by the numerical simulations, suggesting that our stress–strain simulation technique is both qualitatively and quantitatively reliable and useful to clarify the possibility of mechanical fracture of bulk superconductors.</jats:p>

Description

Keywords

bulk superconductors, trapped field magnet, mechanical stress, strain gauge measurement, numerical simulation, finite element method

Journal Title

Superconductor Science and Technology

Conference Name

Journal ISSN

0953-2048
1361-6668

Volume Title

32

Publisher

IOP Publishing

Rights

All rights reserved
Sponsorship
Engineering and Physical Sciences Research Council (EP/P020313/1)
Japan Society for the Promotion of Science (15K04646)