Research on vibration avoidance design method of the aero-engine gear transmission system based on web structure optimization

ObjectiveAiming at the problem that the gear transmission system of aero-engines is prone to traveling wave resonance under complex operating conditions, which further restricts high-reliability lightweight design, a vibration avoidance optimization study was carried out on the gear web structure.MethodsFirstly, a surrogate model for gear modal frequencies was constructed based on the Kriging interpolation method and Bayesian hyperparameter optimization, which was used to replace high-cost numerical analysis and efficiently predict the influence of structural parameters on natural frequencies. Secondly, taking the web thickness ratio and rim ratio as design variables, a mathematical optimization model was established with the objectives of minimizing system mass and maximizing comprehensive mesh stiffness. Then, the surrogate model was embedded into the Non-dominated Sorting Genetic Algorithm Ⅲ (NSGA-Ⅲ) framework, and multiple constraints including resonance speed margin were imposed to conduct multi-objective iterative optimization. Finally, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was adopted to comprehensively evaluate the Pareto front solutions and select the optimal structural scheme.ResultsThe results show that the coefficients of determination (<italic>R</italic>²) of the established surrogate model for the first three nodal diameter natural frequencies of gears reach 96.7%, 94.7%, and 98.8%, respectively, indicating that the prediction accuracy satisfies engineering design requirements. After optimization, the resonance points of six gears with traveling wave resonance risks under continuous and high-speed operating conditions are all effectively avoided. Compared with the initial design scheme, the total mass of the gear set is reduced by 14.4%, while the contact and bending fatigue safety factors of each gear still meet the strength standards of being greater than 1.25 and 1.5, respectively.