Electromechanical Behavior of IBAD/MOCVD YBCO Coated Conductors Subjected to Torsion and Tension Loading

Combined twist and tensile loading states are expected in many applications of YBCO coated conductors. Wire twist is introduced due to winding on complex shapes or for AC loss reduction, while tensile loading originates from sources such as differential thermal expansion and inertial forces. In this study, we analyse the electromechanical behavior of an IBAD/MOCVD YBCO coated conductor configuration with the superconducting layer deposited on hastelloy substrate and encapsulated by copper. The effect of pre-applied twist on degradation of current carrying capability as a function of tensile stress was studied via experimental measurements on tapes with 1 micron thick YBCO layer and 50 micron thick hastelloy substrate at 77 K. In addition, the stress states under pure torsion are modeled using continuum mechanics. Both numerical and approximate analytical solutions are presented, and the stress and strain distributions as a function of applied twist angle are analysed.