Stiffness and damping of an axial superconducting magnetic bearing

An axial superconducting magnetic bearing with radial symmetry has been des igned using NdFeB permanent magnets levitating on a set superconducting mon oliths of YBCO, prepared by top-seeded-melt-texturing technique. The air ga p, stiffness and damping od the bearing, has been measured for different fi eld cooling distances. The elastic constants for axial and radial displacem ent have been obtained from frequency and decay rate of the free vibration curves, taken for different air gaps. The resulting data indicate that the bearing stiffness is dependent on the cooling distance and exhibits no sign ificant dependence on the oscillation amplitude. Conversely, the damping fa ctor exhibits a strong dependence on oscillation amplitude.