Abstract
Bump foil journal bearings are prospective applicants that can support a small-sized rotor of high-speed rotary machinery. In the previous report two models were presented to the bearing, one of which corresponds to the bearing with an excessive static friction between the top and bump foils and the other to the bearing without the friction, and the assembly preload was shown to have a large influence on the maximum load-carrying capacity of the bearings. In this report the stability threshold speed of a horizontal rigid rotor supported in the bearings are predicted, by applying the frequency response method. It is shown that the assembly preload has an effect on the stability and the larger assembly preload results in the larger modified stability threshold speed, where the mean radial clearance in the assembled bearing is chosen as the representative clearance, of the bearing with no friction.
