Abstract
This paper describes a finite element model for rotor-bearing systems, which has been used to estimate the natural frequency of the rigid-body-vibration mode largely affecting electromagnetic noise in small induction motors. In this model the rotor core is represented by beam elements which have an equivalent value of Young's modulus to the real structure, and the bearings are modeled using spring elements arranged in radial and rotational directions. The bearing stiffnesses in both directions are obtained using an experimental apparatus which can identify the stiffness in each direction. Experimental verification shows that the natural frequency of the mode can be calculated to within 2%, using the values for radial and rotational stiffnesses.
