ANSYS software is used to calculate the natural frequency of the central bevel gear of an aeroengine, and the static frequency calculation results are obtained. The first-order vibration mode and dynamic stress distribution from 0 pitch diameter to 4 pitch diameter are shown in Fig. 1 to Fig. 10.
Because the power of the disk (gear) with vibration modes of more than 2 pitch diameters is self balanced, it will not produce bending moment at the connection between the disk (gear) and the shaft, that is, it will not exchange energy with the shaft, so it is a closed energy system; The bending or torque of the disk (gear) with only one pitch diameter vibration mode is coupled with the bending of the rotor and transmitted to each other. This is caused by the vibration of the rotor system, which is called motion excitation. Therefore, 1 pitch diameter is mainly represented by shaft vibration, while 2 and 3 pitch diameter resonance is the main vibration mode of aviation gear.
By comparing and analyzing the vibration modes and vibration stress distribution of driving bevel gear and driven bevel gear, it is found that when the pitch diameter vibration of bevel gear occurs, the position of the maximum vibration stress is basically located at the bottom of the flange tooth groove. Once the resonance occurs, the crack will soon appear at the bottom of the tooth groove and expand, causing devastating damage to the bevel gear.
According to the introduction of traveling wave resonance of bevel gears, the traveling wave resonance of the pair of bevel gears is analyzed. The resonance speed diagrams of driving and driven bevel gears are shown in figures 11 to 18:
From the resonance speed diagram, it can be seen that the front traveling wave resonance speed of the second-order pitch diameter of the central drive driving bevel gear is 17187r / min, and the working speed range of resonance is 15468r / min ~ 18905r / min; The resonance speed of the backward traveling wave is 15784r / min, and the working speed range of resonance is 14205r / min ~ 17362r / min. The resonant speed of the front traveling wave of the first order of the four pitch diameter of the central drive driving bevel gear is 10864r / min, and the working speed range of resonance is 9778r / min ~ 11951r / min; The resonance speed of the backward traveling wave is 9160r / min, and the working speed range of resonance is 8244r / min ~ 10076r / min.
The forward traveling wave resonance speed of the second-order pitch diameter of the driven bevel gear of the central drive is 19680r / min, and the working speed range of resonance is 17712r / min ~ 21648r / min; The resonance speed of the backward traveling wave is 17806 R / min, and the working speed range of resonance is 16025 R / min ~ 19586 R / min. The forward traveling wave resonance speed of the driven bevel gear of the central drive with the first order of 4 pitch diameter is 15220r / min, and the working speed range of resonance is 13698r / min ~ 16742r / min; The resonant speed of the backward traveling wave is 12453r / min, and the working speed range of resonance is 11208r / min ~ 13698r / min.