Enhancement of tensile stress near a hole in superconducting trapped-field magnets

Abstract

The mechanical stress caused by flux pinning in a cylindrical superconductor with a concentric hole is investigated theoretically. Exact expressions for the radial and hoop stress are derived using the critical-state model. Stress profiles during a magnetization process often used to activate high-T c superconductors as strong trapped-field magnets are presented and analyzed in detail. It is shown that due to the hole the tensile hoop stress is enhanced by a factor of 2 or more, depending on the hole diameter. The dramatic increase in cracking probability is emphasized.

Exponent model for stress distributions in a superconducting cylinder with a concentric elliptic hole

“…2, in our calculation, the element type of 4-node quadrangle is adopted, and that the Poisson ratio υ = 0.3 is assumed. Also, it is noted that as p = 0, the present exponent model is, in fact, the known Bean model, and that the analytical results of a superconducting cylinder with a circular hole for the Bean model have been analyzed before by Johansen et al [11]. Thus, in order to verify the validity of the present finite element method, the comparisons of our present numerical results corresponding to a circular hole with the known analytical results are firstly made.…”

“…The high temperature superconductor, however, is susceptible to mechanical failure due to their brittleness and drawbacks [6]. Thus, the magnetoelastic behaviors in a long circular superconducting cylinder or a rectangular superconductor placed in a parallel magnetic field were widely studied [7][8][9][10][11][12][13][14][15]. In addition, the mechanical response of a superconducting thin disk was further investigated [16,17], and the analytical solution to the stresses in a flat superconducting strip with transport current was recently given by Yong and Zhou [18].…”

Fracture problem of a nonhomogeneous high temperature superconductor slab based on real fundamental solutions

“…Çelebi and _ Inanir reported normalstate contribution on the pinning induced magnetostriction [7,8]. The mechanical stress caused by flux pinning on superconductor was investigated theoretically by Johansen and Yong [9,10]. Yong et al (2012a) quantitatively illustrated the effects of coupling parameters on magnetostriction and magnetization [11].…”

Mechanical Stress in the Superconducting Film Under External Magnetic Field

“…Then, more complex structures or critical state model are considered to predict the mechanical deformation and stability [18][19][20]. The stress distribution of an infinite hollow superconducting cylinder was studied analytically [21]. In addition, filling nonsuperconductive materials in the central hole can suppress the hoop stress concentration [22].…”