This study aims to implement multi-objective optimization of a gear unit in order to minimize the power loss and the vibrational excitation generated by the meshing, via a multi-scale approach that extends from gear contact to the complete transmission. All these indicators are closely linked to the macro and micro-geometry definition of the gear pair. The optimization is carried out using a genetic algorithm, namely the Non-Dominated Sorting Genetic Algorithm II (NSGA-II). The design variables chosen for the problem are the pressure angle and the helix angle, as macro-geometry characteristics of the gear, and/or the length and the amount of tooth profile modifications, as micro-geometry characteristics of the gear. Constraints are imposed in order to not exceed a maximum bending stress at the tooth root of the gear and to not fall below a minimum total contact ratio. From the results obtained, it is found that the multi-objective optimization with both micro and macro-geometry parameters simultaneously gives different results than those obtained with macro-geometry first and then micro-geometry parameters. In order to study the importance, or not, to take into account the complete gear unit, a comparison is made between the local power loss generated by gear tooth friction and the total power loss in the single stage gear unit in terms of design variables values.

本研究旨在通过从齿轮接触延伸到整个传动装置的多尺度方法，对齿轮装置实施多目标优化，以最大限度地减少啮合产生的功率损失和振动激励。所有这些指标都与齿轮副的宏观和微观几何定义密切相关。使用遗传算法进行优化，即非支配排序遗传算法 II (NSGA-II)。为该问题选择的设计变量是压力角和螺旋角，作为齿轮的宏观几何特征，和/或长度和齿廓修改量，作为齿轮的微观几何特征。施加约束是为了不超过齿轮齿根处的最大弯曲应力并且不低于最小总接触比。从获得的结果可以发现，同时使用微观和宏观几何参数的多目标优化与先使用宏观几何然后再使用微观几何参数获得的结果不同。为了研究是否考虑到整个齿轮装置的重要性，在设计变量值方面对齿轮齿摩擦产生的局部功率损失与单级齿轮装置中的总功率损失进行了比较. 发现同时使用微观和宏观几何参数的多目标优化与先使用宏观几何参数再使用微观几何参数获得的结果不同。为了研究是否考虑到整个齿轮装置的重要性，在设计变量值方面对齿轮齿摩擦产生的局部功率损失与单级齿轮装置中的总功率损失进行了比较. 发现同时使用微观和宏观几何参数的多目标优化与先使用宏观几何参数再使用微观几何参数获得的结果不同。为了研究是否考虑到整个齿轮装置的重要性，在设计变量值方面对齿轮齿摩擦产生的局部功率损失与单级齿轮装置中的总功率损失进行了比较.