STUDIES ON DYNAMICAL STATE STABILITY OF THE AERO-ENGINE ROTOR JOINT STRUCTURES

This study investigated the dynamical state of joint structures and the influence of joint structures on the rotor dynamics. The sensitivity of critical speeds and vibration modes on typical parameters of joint structures were also discussed. The finite-element models were established by using 3D solid elements and surface-to-surface nonlinear contact elements between the interfaces for numerical analysis. The experimentation for measuring the static rigidity and dynamic contact state of bolted joints with different experimental cycles were performed. Both numerical simulation and experimental results showed that: Firstly, the stiffness of joint structures was not constant. There was a critical load F-cr. when the external load was less than F-cr, the rigidity of joint structures was K-1; when the external load was more than F-cr, the rigidity of joint structures would drop to K-2. The critical load F-cr was influenced by the length of interfaces and preload. Secondly, the contact state of joint structure interfaces varied after a long time of operating with alternating loads. Finally, a sensitivity analysis of critical speeds and vibration modes with respect to typical parameters (joints structure stiffness) is performed with finite difference method, two approaches are carried out, including relative sensitivity analysis and absolute sensitivity analysis. The effect of the parameters on rotor dynamics is captured, as well as the variation range of critical speed. It is advisable to consider the influence of the position, structural parameter and external load of the rotor joint structures on aero-engine structure dynamics design.