Abstract: An apparatus for electromagnetically and rotationally vibrating a rotary body that is supported by bearings. The apparatus comprises a ring-shaped magnet bipolarly magnetized and mounted coaxially on a shaft of the rotary body, a ring-shaped stator having a coil and adapted to generate a rotating magnetic field by controlling an electric current supplied to the coil, and a frequency variable vibration power source adapted to supply alternating electric power to the coil in the stator. The distance between a location of a magnetic pole in the stator and an axis of the shaft is different than the distance between a location of a magnetic pole in the magnet and the axis of the shaft. The magnet and the stator are disposed so as to be adjacent to each other. Thus a rotational exciting force is applied to the rotary body by an interaction of the rotating magnet field generated by the stator with the magnet.

Abstract: An apparatus for electromagnetically and rotationally vibrating a rotary body that is supported by bearings. The apparatus comprises a ring-shaped magnet bipolarly magnetized and mounted coaxially on a shaft of the rotary body, a ring-shaped stator having a coil and adapted to generate a rotating magnetic field by controlling an electric current supplied to the coil, and a frequency variable vibration power source adapted to supply alternating electric power to the coil in the stator. The distance between a location of a magnetic pole in the stator and an axis of the shaft is different than the distance between a location of a magnetic pole in the magnet and the axis of the shaft. The magnet and the stator are disposed so as to be adjacent to each other. Thus a rotational exciting force is applied to the rotary body by an interaction of the rotating magnet field generated by the stator with the magnet.

Abstract: A method and apparatus for evaluating the vibration of a rotary body in a static or non-rotational state to determine a profile of critical speeds including profiles of critical speeds which exist beyond a rated revolution velocity of the rotary body. This invention comprises: a plurality of bearings for maintaining the rotary body in a non-rotating or static condition; a rotary vibrator for applying an exciting force which is rotated about a shaft to the rotary body; a vibration sensor for detecting the vibration of the rotary body; a vibration meter for measuring an output from the vibration sensor; and a vibration power source for supplying AC power to the rotary vibrator and for sweeping a frequency of the exciting force applied from the rotary vibrator to the rotary body from a low-frequency region to a high-frequency region.