A displacement-energy model of studying the delaminating behavior of multi-layer REBCO coated conductor tapes

Abstract

A displacement-energy model (DEM) based on the classical plate theory and Hamaker method was developed to study the delaminating behavior of multilayer rare-earth barium copper oxide (REBCO) coated conductors (CC) tapes. Hamaker method focused on the extreme manifestation of Casimir effects such as cohesion/adhesion between bodies/surfaces and their associated energies. On this model, we studied the supposed defects (in-plane and interface relative separation displacement) created due to thermal mismatch of layers during deposition processing and free vibration of layers in time, and further the effect of these actions on the damage evolution of the CC tape. In the studied American Superconductors (AMSC 344®), the relatively thin films (silver, YBCO, and buffer layers) were modeled as a membrane, while the substrate (Ni-5W) was modeled as a thin plate (shell). We validated the DEM approach by a full 3-D Finite Element Method (FEM) counterpart model. The calculated results showed that unequal and scattered relatively weaker points located in the delaminating region of the CC are responsible for the delaminating behavior of multi-layer REBCO CC tapes, and the results of the location of weakest points with time indicates that delaminating starts at any of the layers' interface or simultaneously in more than one interface. Furthermore for this kind of REBCO CC tapes (for example AMSC 344®), we found that the most vulnerable interfaces to de-bonding are Ni-5W/Y2O3, CeO2/YBCO, and YBCO/silver stabilizer.