For gear 1 and gear 2, they are two pieces of single gear, and the same gear has the same stress, so the power amplification factor can be taken as 1 ３。 The maximum input power of gear 1 and gear 2 is the maximum input power of a single engine, and 1.3 times of this power is taken as the test load. During the test, it shall be noted that the test load shall not be applied at the same time on the left and right sides, which will cause excessive load on the subsequent drive chain. The test load shall be applied on one side and the remaining load meeting the total power requirements shall be applied on the other side.
For gears 3, 4 and 5, they are all single-piece gears, so the power amplification factor is 1.4. Select the maximum input power of the twin engines, and take 1.4 times of this power as the test load.
For gears 6, 7, 8 and 9, considering that gears 7 and 8 are five pieces of a single set, the power amplification factor of fixed shaft gear train can be 1.3. It should be noted that due to the influence of processing and assembly errors, it is necessary to introduce the uneven load factor. The uneven load factor should be properly given in combination with practical experience and process maturity as a correction of the test load.
For gears 10, 11 and 12, considering that gear 11 is a single set of 6 pieces, the power amplification factor of planetary gear train can be taken as 1.3. At the same time, the correction of uneven load factor on test load should also be considered.
According to the analysis, calculate the ratio of rotor internal and external shaft power in the power spectrum. In the power spectrum, the power ratio of the rotor inner and outer shafts is distributed between 0.72 and 0.76, which makes the reducer efficiency change around 0.97, maintaining a high efficiency, and does not form a power internal cycle.
Given the power of the rotor inner and outer shafts in the power spectrum, the actual power transmitted by the fixed shaft gear train and the planetary gear train can be calculated, and the calculation formula is as follows:
Through the formula, it is not difficult to find that the power of the inner and outer shafts of the rotor is mainly provided by the planetary gear train, while the fixed-axis gear train mainly plays the role of realizing the inversion of the inner and outer shafts of the rotor. For the gears of fixed shaft gear train, on the one hand, the transmission power is relatively small; On the other hand, according to HB/Z84.1-4 Calculation of the Bearing Capacity of Aviation Involute Cylindrical Gears, the gear contact and bending fatigue strength are calculated, and the safety factor of the fixed shaft gear train is calculated to be greater than 3. According to the experience in CAL08.004, the fatigue test can be omitted for the gear with the safety factor greater than 3. Therefore, when assessing the fatigue life of the gear chain, the planetary gear train is the main assessment, and the fixed shaft gear train is not the assessment target.