Abstract
Vibrations of a rotor supported by a repulsive type passive magnetic bearing are investigated. The restoring force of a repulsive type magnetic bearing is calculated numerically. Then, this obtained restoring force is approximated by the cubic power series expression. The influences of magnet length and discrepancy between inner and outer magnet positions are investigated. The system shows hard spring characteristic when the difference between the length of inner magnet and outer magnet is small, while the system shows soft spring characteristic when the difference is large. Furthermore, the system shows hard spring characteristic when the discrepancy between inner and outer magnet positions is small, while the system shows soft spring characteristic when the discrepancy is large.
