Experimental study on composite traveling wave resonance of high-speed thin-web spur gear of turbofan engine with a newfound phenomena

The occurrence of gear traveling wave resonance has the characteristics of occasionality, concealment and serious consequences, which has become first of the main factors threatening the safety of aero-engines. In this study, the high-speed thin-web plate spur gear of the turbofan aero-engine accessory casing transmission system is taken as the research object. The traveling wave resonance experiment of the aviation high-speed thin-web plate spur gear is carried out based on the multi-parameter test of vibration, noise and stress. The traveling wave resonance mode, dynamic response characteristics and stress distribution of the aviation high-speed thin-web plate spur gear are studied and analyzed. Through experimental research, the phenomenon of coexistence of multiple traveling wave resonances in the working speed range of aviation high-speed thin spoke plate spur gear is found for the first time, and the frequency expression of gear composite traveling wave resonance is established. The two traveling waves of the composite traveling wave resonance can be the forward and backward traveling waves of different nodal diameters, or the arbitrary superposition of the forward and backward traveling waves of the same nodal diameter. This discovery further improves the gear traveling wave resonance theory. The composite traveling wave resonance at high speed is the main reason for the fatigue fracture fault of aviation high-speed thin spoke plate spur gear. By increasing the thickness of the gear spoke plate, the gear does not appear traveling wave resonance under high speed conditions, which will effectively reduce the risk of gear fatigue fracture.