Deformation Behavior of Stacked REBCO Tapes under Compressive Loads

Recently, structural analysis related to stress and strain has become increasingly important in the design of high-field, high-temperature superconducting (HTS) magnets using Rare-Earth Barium Copper Oxide (REBCO) tapes. Superconducting magnets can be subjected to compressive loads due to various factors such as winding tension, Lorentz force, and thermal contraction. Deformation in superconducting magnets is typically predicted based on the material properties of REBCO tapes. However, the deformation behavior in the stacking direction under compressive stress conditions, influenced by uncertain contact conditions, continues to be an area of investigation. In this study, we measure and analyze the stress-strain characteristics of stacked REBCO tape under compression in the stacking direction to obtain a mechanical property. The experiments are conducted at room temperature using specimens with varying numbers of stacked layers, during which we measure displacement and deformation while gradually increasing the compressive stress up to 100 MPa. Additionally, consecutive three loading-unloading experiments are conducted to analyze the changes in stress and strain characteristics due to local plastic deformation. Furthermore, we employ a 3D laser microscope to measure the change of surface roughness. The stress-strain characteristics obtained from the experiments are expected to contribute to improving the accuracy of various high-magnetic field superconducting magnet designs.