Influence of ring gear flexibility on fatigue reliability in large aerospace planetary mechanisms

The flexibility of the ring gear significantly influences the mechanical properties of planetary transmission at both the tooth meshing level and the system power split level,making it one of the most important design factors determining the service reliability of large aerospace planetary mechanisms. To analyze the way and extent to which the rim flexibility of the ring gear affects the fatigue reliability of the planetary system,a planetary system reliability assessment model is developed using the stress-strength interference theory and the full probability formula calculation. The model incorporates load and strength input variables obtained through the lumped mass finite element method and probabilistic life transformation test of the gear teeth. Finally,the mapping relationship between rim thickness and the reliability index of the planetary system is established,and the thickness range of the ring gear rim with the best reliability gain effect under the mass constraint is accurately determined. This study provides a technical reserve for the fatigue reliability design of large aviation planetary systems.