Delamination Properties of YBCO Tapes Under Shear Stress Along the Width Direction

Abstract

In YBCO coils, the increased transport current density and magnetic field will induce larger electromagnetic force, and YBCO coated conductors (CCs) may suffer interlayer delamination by shear forces, which may give rise to performance degradation of the conductor. The delamination characteristics of YBCO CCs under shear stress should be well understood for better application of YBCO tapes to high-temperature superconducting equipment. This paper describes the experimental results for different delamination strength and critical current I c degradation behaviors of the YBCO CCs under shear stress at the unslit edge, center, and slit edge of the conductor. The results show that the average delaminated shear strengths of 4.9, 5.9, and 3.7 MPa are recorded for the unslit edge, center, and slit edge at room temperature, whereas 6.8, 7.2, and 5.1 MPa are recorded for the unslit edge, center, and slit edge at liquid nitrogen. The different degradation behaviors of I c under shear stress are related to the location where delamination occurs in the sample. According to the finite-element method analysis for the stress distribution of the conductor under shear stress, stress concentration leads to initial delamination of the conductor. The decrease of moment arm is suggested to reduce the effect of moment on the delamination test.

Flux front dynamics and energy losses of magnetically anisotropic 2G-HTS pancake coils under prospective winding deformations

“…Nevertheless, it is worth mentioning that the threshold value for the misalignment factor, depends on the maximum width of the HTS tape that can be situated out of the collinear configuration (perfect winding), as long as it does not exhibit delamination behaviours, due to shear stresses between the different turns of the A c c e p t e d M a n u s c r i p t HTS coil [23], which could also be mitigated by the use of adequate insulation systems [24]. Hence, for the case of the SCS4050 tape that has been considered in this study, the maximum misalignment factor δ m = 1/10 is a plausible threshold value as this has been already demonstrated for up to a 5 − M P a applied stress level with a 8 × 3 mm width anvil, the shear stress at less than 0.25 mm from the tape edges results negligible [25]. Due to the substantial resolution that is needed to account for the local behaviour of the physical variables, with geometry changes of the order of microns, the finite element meshing that composes the 20-turns pancake coils ( Fig.…”

Tермомагнитная Стабильность И Токонесущая Способность REBCO-лент Без Медного Покрытия При 4.2 K

“…Причем, первые две силы были приложены к тончайшему сверхпроводящему слою, а третья -ко всему сечению ВТСП ленты [10][11][12].…”

Measurement of Transverse Tensile Interfacial Strength of REBCO-Coated Conductors

“…Once the transverse stress on the CC tape is greater than its interfacial delamination strength, severe degradation occurs irreversibly. Some testing methods have been used to investigate the delamination behaviour of REBCO CC tapes, including the anvil and pin-pull transverse tensile tests [21][22][23][24][25][26][27], peel tests [28,29], cleavage tests [30], and anvil shear tests [31]. Among them, the anvil and pin-pull transverse tensile tests are widely used to determine the transverse tensile delamination strength.…”