Effects of the contact configurations on the nonlinear dynamics of a rotor-stator contact system

This study delves into the effects of the contact configurations on the nonlinear dynamics of rotor-stator contact systems through analytical investigation. In rotating machinery, the occurrence of harmful vibrations known as rubbing has been reported when the rotor and stator come into contact at specific rotational speeds. To prevent this phenomenon, the characteristics must be understood. This study focuses on the contact configurations between the rotor and stator, emphasizing the stator thickness. Therefore, a contact model that considers the effects of these contact configurations has been developed. The contact detection between the rotor and stator is conducted analytically by considering their geometric shapes and orientations. The influence of contact from the stator to the rotor is represented by an external force, calculated using the Kelvin-Voigt model, and an external moment, determined by the working point of the external force along the axial direction. The analysis is centered on an overhung rotor, which is modeled using the finite element method. Through bifurcation analysis, the main behaviors of the rotor-stator contact system are observed by utilizing the proposed contact model, demonstrating the validity of the contact model. The bifurcation diagram reveals that the band in which partial contact motion occurs tends to shift toward higher rotational speeds as the stator thickness increases. This shift is attributed to the stiffening effect caused by the substantial reduction in clearance and the impact of the external moment resulting from consideration of the stator thickness.