Critical current degradation behaviour in Bi-2223 superconducting tapes under bending and torsion strains

Abstract

In this paper, we have investigated the Ic degradation behaviours in Ag alloy sheathed Bi-2223 superconducting tapes under bending and torsion strains. In particular, we have examined the homogeneity of Ic degradation along the longitudinal direction of tapes by adopting multiple voltage terminals. The bending modes influenced the Ic degradation behaviour in Bi-2223 tapes. A gradual and consistent decrease of Ic could be observed at all sections, which was a different behaviour from that under tensile loading. Up to εirr, Ic showed a nearly similar degradation at each section, due to a simultaneous initiation of cracks from defects indicating that uniform deformation occurred in tapes with bending. Over εirr, some variations in the Ic degradation occurred due to the difference of crack growth rates at each section. In particular, the behaviour appeared significantly with hard bending. The degradation of Ic in Bi-2223 tapes by torsion occurred gradually when the torsion angle exceeded 150°. However, the Ic degradation by torsion strain was small compared with other types of loading. Also, the Ic degradation behaviour at each section along the longitudinal direction of tapes was gradual and consistent, representing a uniform torsional deformation in the tapes.

Bending strain effects on the critical current in Cu-stabilized IBAD/EDDC processed SmBCO coated conductor tape

“…2. This rig is suitable for the test of thin CC tapes in the easy bending mode [13]. The tape was mechanically connected to the current terminal blocks instead of soldering.…”

“…However, in applications to electrical devices such as power cables, motors and magnets, HTS tapes are subjected to various kinds of stresses and strains [5][6][7][8][9][10][11][12][13][14][15]. The investigation of I cstrain/stress behaviors of ReBCO CC tapes will be of great significance in the design of superconducting devices.…”

“…Among the various types of stresses occurring in superconductors in practical applications, tensile and bending stresses and strains are most common in superconducting wires or tapes when they are fabricated into cables or wound in a coil shape for magnet construction [4,[13][14][15]. Also, during the service life of these tapes, they will be subjected to cyclic/repeated loading caused by various reasons such as re-coiling, thermal cycling, Lorentz force variations due to change in coil current, and alternating centrifugal forces during motor operation.…”

Analytical Formulation of $I_{c}$ Dependence on Torsion of YBCO and BSCCO Conductors

“…The effect of torsion on the critical current (I c ) of HTS conductors has been studied and reported by some authors [4]- [6]. In this paper, using an accurate description of the I c dependence on axial strain, a self-consistent analytical expression of the I c dependence on twist pitch is elaborated for both YBCO and BSCCO conductors.…”

Applicability of Weibull Distribution to Description of Distributed Normalized Critical Current of Bent-Damaged Bi2223 Composite Tape

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] Heterogeneous damage occurs, and the damage evolution behavior differs from specimen to specimen and from location to location within a specimen. [9][10][11][12][13][14] Accordingly, when a number of specimens are tested, the critical current differs from specimen to specimen.…”