With the development of the concept and technology of flying vehicle, automobile gear transmission system has become one of the important bottlenecks limiting its service performance and reliability. Therefore, the dynamic reliability analysis model of gear transmission system of flying vehicle considering the correlation between strength degradation and failure is established. The contact stress and bending stress of automobile gear transmission system under the action of flight load spectrum are calculated, and the symmetrical cyclic stress is transformed by Goodman criterion as the stress input variable of reliability model; Based on the nonlinear fatigue cumulative damage theory, the strength degradation model of automobile gear is established as the strength input variable of reliability model. The following conclusions are drawn:
(1) During the service of the gear transmission system of the flying vehicle, the reliability of each gear in the system is sorted from large to small as follows: ring gear R, bevel gear B2, bevel gear B4, bevel gear B1, bevel gear B3, sun gear s, planetary gear P and idler gear I. Because the contact stress and bending stress of input planetary gear stage planetary gear P and idler gear I are large, and its speed is faster than other gears, its reliability decreases the fastest, which does not comply with the equal strength design principle. It is an important link of structural improvement and optimization.
(2) In the gear transmission system of the flying vehicle, the correlation of gear failure in each subsystem gradually increases along the direction of power transmission. Due to the coupling effect of failure of various components in the gear transmission system of flying vehicle, the reliability of the system is obviously weakened. Considering the failure related service life of 3000 h, the system reliability is 84 01%, compared with the case without considering failure, the reliability is reduced by 5 42%。