Dynamic characteristics of aircraft gear transmission systems under overload level-flight conditions

As a crucial component in aircraft power transmission, gear transmission systems are subjected to time-varying additional inertial loads in a non-inertial environment during aircraft maneuvers. Current dynamic analyses of these systems mostly depend on the inertial coordinate system, which assumes the gearbox is fixed to the ground and ignores the extra effects of base motion. Notably, existing models often use a rigid-flexible coupling approach – treating only key components like shafts as flexible while assuming others such as casings and gear teeth as rigid – which may deviate from the actual dynamic behavior of gear transmissions under maneuvering conditions. To address this limitation, this study establishes a full-flexible coupled multibody dynamics model for gear transmissions under overload level-flight maneuvers. By varying maneuvering acceleration magnitudes, the mechanisms by which maneuvering acceleration affects internal excitation and force characteristics in the system were explored. Results show that maneuvering acceleration induces shaft deformation, causing time-varying fluctuations in the center distance between meshing gears. This further leads to changes in meshing stiffness, transmission error, and tooth backlash. Correspondingly, bearing support force, gear meshing force, and Hertzian contact dynamic stress vary with maneuvering overload-especially the bearing force aligned with the overload direction, which is significantly affected by acceleration. This finding provides a critical theoretical basis for the structural design and dynamic optimization of high-maneuverability aircraft gear transmissions.