Study on the Bending-Torsional Coupled Vibration Characteristics of Power Turbine Rotor Under Typical Maneuvering Flight

The maneuvering flight actions of helicopters introduce additional excitation forces and stiffness, which subsequently affect the vibration characteristics of the power turbine rotor system. To analyze the dynamic behavior of the rotor system under various maneuvering flight conditions, a coupled bending-torsion finite element model was developed by integrating the Lagrange principle with the finite element method. This study investigated the dynamic characteristics associated with bending-torsion coupling of the rotor system during typical flight scenarios, including maneuvering turns, pitch, and synthetic actions. The results indicate that, although the bending-torsion coupling has a minimal impact on vibrations in the bending direction, it generates a torsional vibration frequency that is double the rotor’s rotational frequency in the torsional direction. Various maneuvering actions lead to static offsets in the bending direction, while the torsional direction exhibits vibrations at the same frequency as the rotor’s rotational frequency. Additionally, new subharmonic vibration frequency components are produced in both the bending and torsional directions.