The forward and the backward full annular rubbing dynamics of a coupled rotor-casing/foundation system

Abstract

In this paper the forward and the backward full annular rubs of a coupled rotor-casing/foundation system, by which the motion of the rotor is coupled with that of the casing/foundation even in the no rubbing state, are investigated analytically. First, the forward synchronous full annular rub solutions are solved analytically after proposing an equivalent form of the resultant contact force and their stability is analyzed to determine the parameter regions where the forward full annular rub occurs. Then, the existence condition and the whirl frequency of the dry friction backward whirl (the backward full annular rub) are derived analytically after considering the key features of the self-excited response. Finally, the examples of application are given to show the influence of the system parameters on the full annular rubs and to discuss the possible engineering implications.