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An experimental apparatus was designed and tested to study the thermally induced seizure in bearing. The setup consists of a simple, unloaded journal bearing configuration which lends itself to useful physical interpretation without the complexities that are present in the control of flow rates and eccentricity in a loaded journal bearing in which the clearance would vary with time. The motor was fitted with a current limiter which stopped the motor when the torque exceeded a certain limit. Experiments revealed that with this particular system, the journal speed undergoes a significant reduction with time until the operation is halted by the current limiter, which signifies the occurrence of a seizure. The time of seizure is appreciably influenced by this behavior. A parallel theoretical analysis, which takes into account the speed variation with time, was developed. The analysis includes the derivation of the appropriate governing equations which involve the transient analysis of flow velocity, heat transfer, and thermomechanical expansion of the surfaces, together with the numerical solution. The results of the simulations compare favorably to those obtained experimentally both in trend and magnitude. Finally, general behavior of the system in terms of its time-to-seizure characteristic is illustrated through a series of parametric studies.

The results of extensive amount of thermohydrodynamic simulations are presented in the form of design charts for journal bearings. These charts enable one to evaluate the maximum temperature and an effective bearing temperature. Numerous examples are presented that show the applicability of these charts in predicting bearing performance parameters.

A fully lubricated Petroff's-type journal bearing has been modeled to analyze thermomechanical expansion and determine the conditions in which bearing seizures occur. The model was used to develop ways to avoid thermally induced seizures and guidelines for evaluating the occurence of seizure. The model, which was based on the lumped-system analysis, is ideal for hydrodynamic bearings with small Biot numbers.