Studies on detachment non-linearity at the rotor-stator interface

Abstract

This paper provides a description of a phenomenological model representing a mechanical system consisting of a stator disk fixed to a clamped beam and a rotor disk. When the rotor is in contact with the stator, the rotation gives rise to friction leading to a self-sustaining vibratory instability called whirl. This instability confers a two-beam bending mode to the coupling. Moreover, adding detachment at the rotor/stator interface leads to the disappearance of whirl instability and the onset of another mode known as squeal. The main goal of this paper is to study the conditions of occurrence of the squeal mode. This is the first time a study has been performed to observe 3 different behaviors as a function of the parameters imposed. A limit cycle is associated with each behavior. Then, each limit cycle is studied using spectrograms and state space representation. Attention is then focused on the limit cycle bifurcation and limit cycle stability is studied using the monodromy matrix. Finally, a contact bounce is introduced in the model to observe a limit cycle consisting of alternating whirl and squeal modes.