DYNAMIC RESPONSE AND DAMAGE ANALYSIS OF SPLINE COUPLING UNDER FAN BLADE OFF

Fan blade off (FBO) represents an extreme loading condition during aeroengine working. Within an extremely short period, the rotor system is subjected to significant impact load excitation. This induces a large alternating load under non-coordinated whirl conditions, inevitably causing relative sliding, wear, and plastic deformation at the connection interface, ultimately resulting in the failure of the spline coupling connection structure. This study performs a comprehensive mechanical analysis of the rotor structure with splined coupling following FBO. The dynamic equation governing the rotor's behaviour under FBO is derived. Using the low-pressure rotor as the research subject, the dynamic response of the rotor under FBO is calculated, and the dynamic response of the splined coupling after FBO is analysed. These results serve as input conditions for subsequent damage analysis. The substructure method is employed to investigate the damage to the splined coupling connection structure after FBO. A novel interface damage analysis method based on Archard's friction work principle is developed and applied to evaluate the wear damage of the splined coupling. The findings indicate that the vibration response experiences a sudden increase at the instant of FBO and when the rotor decelerates through its critical speed. After FBO, the radial centring surfaces A and B exhibit relatively severe wear.