Influence of the Movement of the Neutral Axis on the Relation Between the Critical Current and Strain in Bending Bi2223/Ag Composite Tapes.

For the Bi2223/Ag composite tape, on the existence of thermally residual stress, the neutral axis usually shifts away from the center of the cross section due to the Bauschinger effect of Ag and Ag alloy under the bending deformation. The movement of the neutral axis causes the redistribution of the stress and strain in the tape and further affects its critical current. In this paper, based on our modified model with the damage stress of the Bi2223 superconducting filaments, the movement of the neutral axis, the influence of the movement on the relation of the critical current versus the bending strain, and the distribution of the stress and strain on the cross section have been studied. The calculated results show that, the relation of the normalized critical current I/ I versus the bending strain with taking account of the movement of the neutral axis is closer to the experimental data than without that, the neutral axis moves always to the compressive side of the tape, and the movement increases with the bending radius R decreasing (i.e., the bending deformation increasing). Furthermore, in the different cases of the Bauschinger effect factor (BEF), the elastic modulus and volume fraction of the superconducting filaments, the movement of the neutral axis, the normalized critical current I/ I with the bending radius R, and the distributions of the stress on the cross section have been comprehensively investigated. [ABSTRACT FROM AUTHOR]