Dependence of the critical current ofYBa2Cu3O7−δ coated conductors on in-plane bending

Abstract

A new method to measure the effect of in-plane bending on the critical current ofYBa2Cu3O7−δ coated conductors is presented. Such a bending mode can be important in transmissioncables, saddleback magnets, and double-pancake windings. A linear strain distribution overthe width of the conductor develops in this bending mode, where one half of the conductoris under axial compressive strain and the other half is under axial tensile strain. Areversible reduction in critical current of up to 5% is measured in 4 mm wide conductors ata critical bending radius of 0.25–0.28 m. The critical current degrades irreversibly forbending radii less than this because the strain at the edge of the conductor that is undertension irreversibly damages the conductor. The results are described by use ofa model that calculates the critical current as a function of in-plane bendingradius by taking into account the strain gradient over the width of the sampleand the measured dependence of the critical current on axial strain. A similarapproach can be used to calculate the degradation of the critical current n ofother deformation modes, such as torsion, or other more complex geometries.