Considering the problem of life prediction of aero-engine accessory drive system under random fatigue load

a method of fatigue life prediction based on grey estimation and polynomial variation theory was proposed. Based on the grey model and polynomial variation theory

two-dimensional load spectrum and equal amplitude fatigue median surface were obtained. Taking parallel shaft-gear transmission structure as an example

the fatigue median life of the risk point was about 135×107 using Miner fatigue cumulative damage theory. During the verifying test

standard 40Cr-workpieces were under condition of equivalent stress state. The processing process could satisfy the strength standard for aero transmission shaft in conformance to GB3077-82. In life test with equal censored time

the number of samples was 45. Median life for samples was about 142×107. As the result

the calculated value of fatigue median life was slightly less than the test value. The proposed method is reliable and conservative for improving the fatigue life of accessory drive system.