A. Nishimura

H. Tamura

J. Yamamoto

K. Horiguchi

S. Ueda

T. Kobori

Y. Shindo

Y. Takagi

National Institute for Fusion Science (NIFS-Repository)

§23. Cryomechanics of Electromagnetic Materi-als for Superconducting Magnets Shindo, Y., Horiguchi, K., Takagi, Y., Kobori, T. (Dept. of Mater. Processing, Tohoku Univ.) Ueda, S. (Dept. of Technology, Shizuoka Univ.) Yamamoto, j., Nishimura, A., Tamura, H. i) Mechanical Behavior of Superconductig Coils On the development of the superconducting helical coil, it is important to examine the me-chanical behavior of the coil and the evaluation of the coil rigidity at liquid helium tempera-ture. The helical coils in the Large Helical De-vice are subjected to high electromagnetic force of about 10MN /m. First, we consider the me-chanical behavior and the compressive rigidity of the superconducting helical coil pack under compressive load at liquid helium temperature l). Finite element method is used for the nu-merical analysis of the composite structure of the coil pack. The numerical results of displace-ments and strains are obtained and compared with the experimental results. Fig. 1 shows the compressive load versus displacement for the superconducting helical coil pack. Superconducting coil pack ( 4.2K) 0 3D analysis • l.oadin~(Exp.) 0 Unloading(Exp.) Inhomo. Homo. 0.5 1 Displacement (mm) Fig. 1. Compressive load versus displacement for superconducting helical coil pack (3D analysis). The superconducting poloidal coils are sub-jected to the compressive stress of about 20 rv 35MPa. Next, we also consider the displace-ment and strain analysis of the superconduct-ing poloidal coil pack under compressive load at liquid helium temperature 2). The validity of numerical techniques for evaluating the rigidity of the coil pack is examined. ii) Dissipated Energy and Low Temperature Fracture in Cracked Glass-Epoxy Composite Materials In order to evaluate the dissipated energy and the low temperature fracture of glass-epoxy composite materials, which are used in mag-netic fusion energy structures as thermal insu-lation, electrical insulation and structural sup-port at low temperatures, we performed frac-ture toughness testing at 77K and 4.2K. We use 0.4T compact test specimens for the test. Test-ing was conducted in accordance with ASTM standerd E399-83. The effect of the crack length and the loading rate on the dissipated energy and the fracture toughness is examined. iii) Mechanical Behavior of Structural Materials in a Strong Magnetic Field We present experimental evidence and theo-retical analysis for the bending of a soft ferro-magnetic beam plate in a strong magnetic field. The experiments were conducted in the bore of a superconducting magnet at room tempera-ture. Ferritic stainless steel SUS430 is here used as the cantilever specimen for the bending test. The experiments show the predicted increase in the deflection with increasing magnetic field. The theoretical analysis is based on a classical plate bending theory for magneto-elastic inter-actions in a soft ferromagnetic bodies. The ef-fect of the magnetic field on the deflection is discussed in detailed. The theoretical results agree very well with the experimental data. References 1) Shindo, Y. et al. : Cryogenic Engineering 29(1994) 58. 2) Shindo, Y. et al. Cryogenic Engineering (in press). 29 

Cryomechanics of Electromagnetic Materials for Superconducting Magnets

Cryomechanics of Electromagnetic Materials for Superconducting Magnets

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