209 / 2021-03-31 22:54:28

Vibration analysis of crack-blade-disk-shaft coupling system under multi-load excitation

Crack-blade-disk-shaft,Multi-load excitation,Unbalance force,Aerodynamic load,Breathing behavior

The blade-disk-shaft coupling system can easily cause complex vibration response under multi-load excitation, such as unbalance force on the shaft and aerodynamic load on the blades, which is highly susceptible to blade damage and cracks. In this paper, a dynamic model of the crack-blade-disk-shaft coupling system is presented, in which the blades and the shaft are established based on beam theory, the disk is simulated by a lumped mass, and the breathing behaviour of the crack on the blade is achieved based on the contact algorithm. Then, the presented model is verified by a full solid finite element model by comparing the natural frequencies. Finally, the vibration responses of the coupling system are investigated under the unbalance force and the aerodynamic load. The results indicate that: the blade bending vibration is mainly caused by the aerodynamic load, and the influence of unbalance force on blade bending vibration is small; in addition to the rotating frequency component, the side frequency of the passing frequency can be observed in the displacement response spectrum of the shaft; the rotating frequency, the passing frequency, and the side frequency of the passing frequency can be observed in the bending displacement response spectrum of the blade; the multiple frequencies of the passing frequency and their side frequencies in the high-frequency band can be observed due to the blade crack.