Abstract :
Composite superconductors such as Cu/Nb3Sn and Ag/Bi-oxides are subjected to thermally-induced residual strain by other component materials due to the around 1,000 K temperature difference between the reaction temperature and the cryogenic temperatures, and to applied tensile strain by the hoop stress of longitudinal (z) direction during the coil operation. To clarify especially the radial (r) and tangential (θ) strain behaviors including z-strain, we analyzed elastic-plastically multi-core model by computing of FEM for various composite conductors. As a result, applied tensile stress on the z-direction of the composite conductor gave monotonous decrease of thermally-induced rand θ-strains, which changed tensile to compressive strain. With increase in the z-strain effective strain showed the minimum value, not zero, at around z-strain-free state. Moreover it was found that all conductors are classified into three types by combination of component materials.
Keywords :
bismuth compounds; composite superconductors; compressive strength; copper alloys; finite element analysis; high-temperature superconductors; niobium alloys; silver compounds; stress-strain relations; tensile strength; thermal expansion; tin alloys; Bi-2212; CuSn; FEM analysis; Nb3Sn; coil operation; component materials; composite conductors; composite superconductors; compressive strain; cryogenic temperatures; elastic-plastically multicore model; hoop stress; radial strain; reaction temperature; tangential strain; tensile strain; tensile stress; thermal expansion coefficient; thermally-induced residual strain; three directional strain states; z-strain behavior; z-strain effective strain; Capacitive sensors; Composite materials; Conducting materials; Niobium; Superconductivity; Temperature; Tensile strain; Tensile stress; Thermal stresses; Tin; $hboxNb_; Bi2212; FEM; composite superconductor; hboxAl$ ; hboxSn$ ; tensile strain; thermal expansion coefficient;
