An analytical method for predicting the net (thermal plus intrinsic) residual stresses in multilayered yttrium barium copper oxide coated conductors

In this paper, the net (thermal plus intrinsic) residual stresses in the films of American Superconductor (AMSC 344^®) tape was analyzed via a displacement- energy model (DEM) solution approach. The DEM solution approach was developed to predict both the thermal mismatch and intrinsic film stresses in the coated conductor (CC) films thereby avoid the costly experiments usually required to capture the intrinsic film's stress part in CC films. The analysis was based on the force and moment balances method, classical plate theory, and Hamaker method. On this model, the authors studied the generation of misfit strains in the CC films due to the thermal and free-vibration mismatch between the layers, and further the role of these actions in the residual stresses evolution in the CC films. The results showed that the thermal film stress in the yttrium barium copper oxide (YBCO) films calculated by the DEM solution approach was 460.80 MPa, whereas that calculated by the closed-form solution method was 455.30 MPa. Moreover, for the non-textured yttrium-stabilized zirconium (YSZ) films deposited on the Hastelloy C substrate, the calculated net residual stress by the DEM solution approach was 673 MPa, whereas the measured net residual stress by the x-ray Diffraction (${\sin }^2\psi$ Method) was 598 ± 75 MPa. Therefore, the DEM solution approach successfully predicted the net residual stresses in the CC films analyzed because the calculated results by the DEM solution approach agree well with those by the closed-form solution and x-ray Diffraction (${\sin }^2\psi$ methods). (paper)