Abstract
Increasing interest in environmental matters, quite motors are drastically demanded lately. Among of acoustic noise of the motor, electromagnetic acoustic noise is jarring and is studied recently. Electromagnetic acoustic noise is strongly affected by (1) increase of magnetic density by reduction of motor sire and (2) decrease of stiffness by saving weight In order to reduce electromagnetic acoustic noise, it is necessary to design the motors of which natural frequencies do not coincide with electromagnetic force frequencies. In order to avoid the resonance of the natural frequencies of the core and the electromagnetic force frequencies at design phase, machine designers should predict these frequencies accurately. In this paper, vibration modes and natural frequencies of thick cylinder are studied by experiments and Finite Element analyses.
