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.nd edition 2019-07 Foil bearings — Performance testing of foil journal bearings — Testing of static load capacity, friction coefficient and lifetime Paliers-feuilles — Essais de performance des paliers radiaux à feuilles non lubrifiés — Essais de la capacité de charge statique, du coefficient de frottement et de la durée de vie Reference number ISO 13939:2019(E) ？ ISO 2019 ISO 13939:2019