Steady-state response characteristics of a dual-rotor system induced by rub-impact

In this paper, the steady-state responses and their stability of a dual-rotor system with rub-impact are investigated. The nonlinear equations of motion in eight d.o.f.s are obtained with the consideration of the gyroscopic effect. The multi-harmonic balance combined with the alternating frequency/time domain technique (MHB–AFT) is utilized to calculate the accurate amplitude of each harmonic component. Arc-length continuation is embedded in the MHB–AFT procedure to trace the branch of the periodic solutions, and the Floquet theory is used to discuss the stability of the obtained solutions. Through the numerical calculation, complicated nonlinear phenomena, such as combined harmonic vibrations, hysteresis and resonant peak shifting are obtained when the rub-impact occurs. The result also shows that the control parameters such as mass eccentricity, inter-shaft stiffness and rotational speed ratio make significant but different influences on the dynamic characteristics of the two rotors. Therefore, the contribution of this study is to provide a further understanding of the steady-state response characteristics of the dual-rotor system with rub-impact.