Optimization of dynamics of non-continuous rotor based on model of rotor stiffness

Applying a heavy load to the rotor system of aero-engine can drastically reduce the stiffness in rotor joints, which is called “non-continuity” of the rotor and can affect the joint dynamics. Although the dynamics of a rotor system with multiple joints may be negligibly perturbed by a decrease in joint stiffness, this phenomenon is much more striking in advanced, next-generation aero-engines because their rotor structure is lighter and their loads are heavier. We thus investigate the mechanism leading to non-continuity in rotor joints to clarify how joint stiffness deteriorates upon applying a heavy load to rotor joints. This investigation combines a numerical model of joint stiffness with a model of rotor stiffness, which we use to study the dynamic characteristics of a rotor system. The results of the numerical simulation of rotor dynamics reveal that a decrease in joint stiffness leads to a significant concentration of strain energy around the joints when the rotor undergoes bending-mode vibrations, which decreases the critical speed. To avoid loss of joint stiffness and suppress rotor vibration, we develop a method to optimize the support stiffness of the rotor system and demonstrate its effectiveness experimentally.