A rotor dynamic model is built up for investigating the effects of tightening torque on dynamic characteristics of low pressure rotors connected by a spline coupling. The experimental rotor system is established using a fluted disk and a speed sensor which is applied in an actual aero engine for speed measurement. Through simulating calculation and experiments

the effects of tightening torque on the dynamic characteristics of the rotor system connected by a spline coupling including critical speeds

vibration modes and unbalance responses are analyzed. The results suggest that when increasing the tightening torque

the first two critical speeds and the amplitudes of unbalance response gradually increase in varying degrees while the vibration modes are essentially unchanged. In addition

changing axial and circumferential positions of the mass unbalance can lead to various amplitudes of unbalance response and even the rates of change.