Calculation of Nonlinear Unbalance Response of Horizontal Jeffcott Rotors Supported by Ball Bearings With Radial Clearances

Abstract

Nonlinear unbalance response of horizontal Jeffcott Rotors supported by ball bearings with radial clearances are investigated. First, the method to calculate the nonlinear vibration of the rotor as well as the expression of the nonlinear bearing force are given using the numerical harmonic balance technique. It is shown that there are 4 types to the unbalance response, which consist of the horizontal, the vertical, the intermediate, and the circular modes. The former three types of vibrations always take place, but the last appears only when the critical unbalance is exceeded. Moreover, the design technique to avoid the appearance of the last type of vibration is discussed, because the maximum amplitude of the last type may become quite large.