This document describes a method for comparing the performance test results of foil journal bearings, which are lubricated by air (gas) and supported by the gas-dynamic force generated via the rotations of the rotating shaft. The test procedure proposed in this document aims to predict and evaluate the static load capacity, friction coefficient and lifetime of foil journal bearings and compare the results of these parameters under different test conditions, i.e. at varying dimensions of foil bearing, rotational speed of a shaft, pressure and humidity of the surroundings. The magnitude of the static load capacity can change according to the test setting, as the test conditions can be changed.
The test method described in this document has the following application coverage.
a) The criterion for evaluating the static load capacity is the steady-state condition; i.e. the method is applicable under limited operating conditions with uniform magnitude, load direction and rotational speed.
b) The evaluation procedure can be applied only if the foil journal bearing is under a uniform rotating inertia at an arbitrary rotational speed.
c) The dynamic load with time-variant magnitude and direction is not considered.