DYNAMIC STABILITY OF MECHANICAL STRUCTURES CONTAINING EXTERNALLY PRESSURIZED GAS-LUBRICATED THRUST BEARINGS.

A stability criterion is presented to evaluate instability phenomena in mechanical systems containing externally pressurized gas bearings. For this criterion, the gas bearing films and the supporting structure are characterized separately by means of frequency response functions. The overall system may be considered as a feedback-loop for which the Nyquist criterion will define stability limits. The analysis demonstrates the interaction between the dynamics of the supporting structure and the air gap. The stability criterion is generalized for systems containing more than one gas film. The stability criterion is verified experimentally.