Nonlinear dynamics of a dual-rotor-bearing system with active elastic support dry friction dampers

Abstract

In present study, the modified harmonic balance-alternating frequency/time domain (HB-AFT) method with embedded arc-length continuation method is used to study the nonlinear dynamic characteristics of the dual-rotor-bearing system with active elastic support dry friction damper (ESDFD). The friction on the contact interface between ESDFD moving and stationary disks is described by a two-dimensional (2D) friction contact model. The dynamic model of the dual-rotor is established by the conical Timoshenko beam element and the rigid disk element, while the inter-shaft bearing force is obtained by the Hertz contact model. The reduced order model (ROM) of dual-rotor system is constructed by the Craig-Bampton method. Based on the ROM, the modified HB-AFT method with embedded arc-length continuation procedure is used to solve the periodic solutions of the dual-rotor system under unbalanced excitation. The Floquet theory is employed to determine the stability of periodic solutions. The impact of key parameters such as Hertz contact stiffness and radial clearance of inter-shaft bearing, eccentricity of disk, and modal damping ratio on the primary resonance characteristics and inter-shaft bearing dynamic load of the dual-rotor system are revealed without considering the ESDFD. With considering the ESDFD, the influence of ESDFD normal force on the primary resonance peak and inter-shaft bearing dynamic load of the dual-rotor system is investigated. The optimal normal force and controllable region for ESDFD to control the vibration of the dual-rotor system under the target mode is determined. A control strategy based on altering the normal force within the controllable region is designed. Results show that under the proposed control strategy, the damping effect provided by ESDFD significantly reduces the vibration amplitude of the dual-rotor system and mitigates the dynamic load of the inter-shaft bearing when passing through the resonance region, completely suppresses the bi-stable phenomenon and vibration jump behavior of the dual-rotor system. Thereby reducing the structural damage caused by excessive vibration. This demonstrates promising engineering applications for ESDFD.