The radial clearance in rolling bearing systems, required to compensate for dimensional changes associated with thermal expansion of the various parts during operation, may cause dimensional attrition and comprise bearing life, if unloaded operation occurs and balls skid [D. Childs and D. Moyer, ASME J. Eng. Gas Turb. Power 107, 152–159 (1985)]. Also, it can cause jumps in the response to unbalance excitation. These undesirable effects may be eliminated by introducing two or more loops into one of the bearing races so that at least two points of the ring circumference provide a positive zero clearance [D. Childs, Handbook of Rotordynamics, edited by F. Ehrich (McGraw-Hill, NY, 1992)]. The deviation of the outer ring with two loops, known as ovality, is one of the bearing distributed defects. Although this class of imperfections has received much work, none of the available studies has simulated the effect of the outer ring ovality on the dynamic behavior of rotating machinery under rotating unbalance with consideration of ball bearing nonlinearities, shaft elasticity, and speed of rotation. To fill this gap, the equations of motion of a rotor–ball bearing system are formulated using finite-elements (FE) discretization and Lagrange’s equations. The analyses are specialized to a rigid-rotor system, by retaining the rigid body modes only in the FE solution. Samples of the results are presented in both time domain and frequency domain for a system with and without outer ring ovality. It is found that with ideal bearings (no ovality), the vibration spectrum is qualitatively and quantitatively the same in both the horizontal and vertical directions. When the ring ovality is introduced, however, the spectrum in both orthogonal planes is no longer similar. And magnitude of the bearing load has increased in the form of repeated random impacts, between balls and rings, in the horizontal direction (direction of maximum clearance) compared to a continuous contact along the vertical direction (direction of positive zero clearance). This underlines the importance of the vibration measuring probe’s direction, with respect to the outer ring axes, to capture impact-induced vibrations. Moreover, when the harmonic excitation is increased for a system with ideal bearings, the spectral peaks above forcing frequency have shifted to a higher-frequency region, indicating some sort of a hard spring mechanism inherent in the system. Another observation, is that for the same external excitation, vibration amplitude at forcing frequency in the bearing force spectrum is the same for systems with or without outer ring ovality.
Skip Nav Destination
Article navigation
February 2000
February 01 2000
Rotating machinery dynamics simulation. I. Rigid systems with ball bearing nonlinearities and outer ring ovality under rotating unbalance excitation
Fawzi M. A. El-Saeidy
Fawzi M. A. El-Saeidy
Damro-Salman, Desouk, Kafr-El-Sheikh, Egypt
Search for other works by this author on:
Fawzi M. A. El-Saeidy
Damro-Salman, Desouk, Kafr-El-Sheikh, Egypt
J. Acoust. Soc. Am. 107, 851–860 (2000)
Article history
Received:
October 27 1998
Accepted:
October 07 1999
Citation
Fawzi M. A. El-Saeidy; Rotating machinery dynamics simulation. I. Rigid systems with ball bearing nonlinearities and outer ring ovality under rotating unbalance excitation. J. Acoust. Soc. Am. 1 February 2000; 107 (2): 851–860. https://doi.org/10.1121/1.428360
Download citation file:
Pay-Per-View Access
$40.00
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Citing articles via
Focality of sound source placement by higher (ninth) order ambisonics and perceptual effects of spectral reproduction errors
Nima Zargarnezhad, Bruno Mesquita, et al.
Related Content
Simulation of traction electricity supply systems equipped with unbalance-to-balance transformers
AIP Conf. Proc. (March 2023)
Forced vibrations of an elastically supported rigid rotor at different types of unbalance
AIP Conf. Proc. (February 2024)
The influence of mobility unbalance on GaN based vertical cavity surface emitting lasers
Appl. Phys. Lett. (April 2008)
Control of line voltage unbalance factor in three-phase distribution grids caused by single-phase photovoltaic systems
J. Renewable Sustainable Energy (April 2022)