Load sharing analysis and reliability prediction for planetary gear train of helicopter

Due to inevitable manufacturing and installation errors, there are many problems of unequal load sharing in planetary gear train. In this paper, a model is established to predict the reliability of helicopter planetary gear train under the condition of partial load. Firstly, the structure of gear system and partial load state are analyzed in detail, and the load histories of each gear are transformed into equivalent constant amplitude load spectrums to be as the load input variable for reliability model. At the same time, a tooth bending fatigue test is carried out with specific gears, and the statistical results of test data are as the strength input variable for reliability model. Then, according to partial load characteristics of the gear system, the reliability model is established based on the concept of minimum order statistic. Finally, the bad influence of unequal load sharing on planetary gear train is shown by prediction result and the reliability model is verified through a statistical analysis method of random censored data.