A new refined modeling method for rotating inter-shaft elastic support considering preload effects: Theoretical and experimental validation

The rotating inter-shaft elastic support effectively mitigates strain energy concentration at critical speeds in flexible dual-rotor systems. In-depth research on the modeling of such systems is therefore of significant importance. To address this, the influence of preload force is analyzed, and the characteristic matrix of the rotating inter-shaft elastic support is derived using Hamilton’s principle. Based on the Lagrange equation, a dynamic model of the dual-rotor system with the rotating inter-shaft elastic support was established. The dynamic characteristics were then investigated using a combination of analytical calculation methods and Newmark-β numerical method, and the model’s validity was further verified through experiments. The results show that under normal circumstances, the rotating inter-shaft elastic support provides an additional stiffness to the dual-rotor system. In the case of unidirectional preload loss, the translational stiffness of the rotating inter-shaft elastic support decays, and the generalized force term is introduced in the angular freedom. This causes a change in the fundamental frequency amplitude of the rotor in the dual-rotor system, and the change is significant in the critical speed state. The error between the calculated and experimental values of the critical characteristics of the dual-rotor system with rotating inter-shaft elastic support is less than 3%, offering improved accuracy over the conventional single-stiffness modeling approach. As the pretension loss rate increases, the amplitude of the low-pressure (LP) rotor vibration response in the critical state shows a trend of first decreasing and then increasing. The study reveals the dynamic mechanism of the rotating inter-shaft elastic support, providing a theoretical basis for the dynamic design of flexible dual-rotor systems.