Strain dependence of critical current and self-field AC loss in Bi-2223/Ag multi-filamentary HTS tapes: a general predictive model

Abstract

It is well known that mechanical deformations have a strong impact on the critical current (I c ) of Bi-2223/Ag multi-filamentary high-temperature superconducting (HTS) tapes, and a remarkable I c degradation is induced, which results in a significant AC loss. In this paper, a general predictive model based on the strain dependence of the Weibull distribution function of statistical damage of superconducting filaments and the Norris formula is developed to explore the influence of the uniaxial, bending and torsional deformation on I c degradation and self-field AC loss of Bi-2223/Ag HTS composite tapes. A unified strain dependence of the I c formula is suggested, which is extended in view of the I c degradation mechanism of Bi-2223/Ag HTS tapes under a uniaxial deformation with an introduction of longitudinal strain to unify the strain in uniaxial, bending and torsional deformation modes. Then, a modified Norris formula is deduced in light of the unified strain dependence of the I c model to predict AC loss of Bi-2223/Ag HTS tapes. With a set of appropriate model parameters determined by the tested data of I c under uniaxial deformation, the presented model can well predict both I c degradation and AC loss behaviors under not only a uniaxial deformation mode, but the bending and torsional ones. The proposed model indicates that the significant increase of AC loss for a deformed tape is presented due to the notable degradation of I .

Stress, strain and electromechanical analyses of (RE)Ba2Cu3Oxconductors using three-dimensional/two-dimensional mixed-dimensional modeling: fabrication, cooling and tensile behavior

“…Furthermore, irreversible degradation of I c in both BSCCO-based (e.g. Bi-2212 and Bi-2223) and REBCO conductors has been studied using a statistical approach based upon the Weibull statistics [31,32,[42][43][44][45]. Here a critical current phenomenological model that combines the Ekin power-law formula and the Weibull distribution function with the REBCO conductor model is used to predict the electromechanical behavior of I c in REBCO conductors across the entire strain range.…”

“…Ignoring the linear deformation effect on the REBCO cross-section area, and assuming a uniform distribution of current on the REBCO layer, the normalized critical current A statistical approach based upon the Weibull distribution function has been used to characterize the effective area of undamaged superconducting region under deformation in BSCCO-based conductors [42][43][44][45], and the irreversible degradation of I c in both BSCCO-based and REBCO conductors [31,32]. The statistical ratio of undamaged superconducting cross-section area to the before-damaged superconducting cross-section area under uniaxial loadings, S S , Figure 13 compares the simulation result calculated by (24) against the experimental data taken from [8] for the applied strain dependence of (normalized) critical current.…”

Numerical Study on Mechanical Behavior and Electromechanical Properties of Solder-Jointed REBCO-Coated Conductors

“…In the reversible region, Ekin’s power law was applied for depicting reversible variations of under various mechanical loads [ 45 , 46 , 47 , 48 , 49 ]. In the irreversible region, the Weibull distribution function was applied to depict the irreversible degradation of BSCCO [ 50 , 51 , 52 , 53 , 54 ] and the REBCO CC tapes [ 42 , 43 , 50 , 55 , 56 , 57 ] under mechanical loads.…”

Measurement of Transverse Tensile Interfacial Strength of REBCO-Coated Conductors

“…REBCO CC tapes possess excellent uniaxial tensile strength owing to their strong substrates. Experimental results showed that the maximum uniaxial tensile strength of the second-generation HTS tapes was 700 MPa at liquid nitrogen temperature [11][12][13][14][15], which is much higher than that of the first-generation HTS tapes [16][17][18]. As a typical laminated composite material, however, delamination is a typical failure mode that seriously affects the performance of epoxy-impregnated REBCO coils [19,20].…”