MODELING ASPECTS OF A RATE-CONTROLLED SEIZURE IN AN UNLOADED JOURNAL BEARING

Thermally induced seizure can lead to a rapid catastrophic bearing fai lure. An analytical model was developed to study this phenomenon in an unloaded journal bearing The model consisted of two concentric cylind ers containing lubricant in which the inner one rotates at a specified rpm and the outer cylinder is stationary. The appropriate governing e quations and numerical solution schemes for treating the transient hea t transfer in the fluid and the bounding solids are presented. Computa tions indicate that, depending on the operating conditions and thermom echanical properties, a bearing can rapidly lose its operating clearan ce. A parametric study with an extensive amount of numerical results i s presented. It is shown that the clearance loss variation with time i s initially linear up to a point after which its rate of reduction bec omes much greater. Closely related to this nonlinearity is the behavio r of the friction torque which sharply rises before the clearance tota lly vanishes. The effect of thermomechanical properties, operating spe ed, and convective heat transfer coefficient on the seizure time are i nvestigated.