Abstract
In this paper the stability chart of a linearized self-acting gas journal bearing is assessed by tracing the response of a journal accelerated from an equilibrium state. The response is obtained by the simultaneous time marching solution of the time-transient Reynolds equation and the equations of motion of the journal. For this purpose, the Reynolds equation is cast as an initial value problem via Galerkin's finite element method.
The threshold speed of an accelerating journal may be predicted from the linearized stability chart. However, it is found that the journal bearing system happens to be asymptotically stable well beyond the stability margin in the unstable region of the linearized system. The threshold of accelerating journals actually occurs at speeds nearly 20 percent higher than those given by the linearized stability margin.