The gas generator rotor of a small turboshaft aircraft engine, which operates at a relatively high speed, may have support stiffness that is weakened by the deliberate reduction of its structural weight, potentially causing a coupling vibration between the gas generator rotor and the engine's central-driven bevel gear (CDBG). The vibrating CDBG can be exposed to a complex pattern of excitation caused by lateral vibration of the rotor and meshing between gear teeth, resulting in possible fatigue damage of the CDBG. In experiments with a typical turboshaft engine, several fatigue fracture failures occurred, and the fatigue cracks were found to propagate radially toward the center of the disk, which is noticeably different from common fatigue failures of gear systems. In this paper, both the gas generator rotor of a turboshaft engine and the CDBG are investigated, and a dynamic model of the rotor-gear system that takes account of multi-source excitation is established. The vibration response of the CDBG, as well as the mechanism by which the fatigue crack is initiated and propagated, were studied. The research shows that in addition to high-frequency excitation arising from gear-teeth meshing, the lateral vibration of the gas generator rotor will also generate a 2× excitation on the CDBG. Thus, under multi-source excitation, the CDBG disc undergoes both a high-frequency 5th nodal diameter mode and a low-frequency swing-shaped vibration mode. The high-frequency excitation causes an initial crack at the root of the gear tooth, and the crack propagates under low-frequency vibration stress, eventually causing fatigue fracture of the CDBG structure.

小型涡轮轴飞机发动机的气体发生器转子以相对较高的速度运行，其支撑刚度可能会因故意减轻其结构重量而减弱，从而可能导致气体发生器转子与发动机中央发动机之间的耦合振动。从动锥齿轮（CDBG）。振动的CDBG可能会受到由转子的横向振动和齿轮齿之间啮合引起的复杂激励模式的影响，从而可能导致CDBG疲劳损坏。在使用典型涡轮轴发动机的实验中，发生了数个疲劳断裂故障，并且发现疲劳裂纹沿径向向盘中心传播，这与齿轮系统的常见疲劳故障明显不同。在本文中，研究了涡轮轴发动机的气体发生器转子和CDBG，并建立了考虑多源激励的转子-齿轮系统的动力学模型。研究了CDBG的振动响应以及疲劳裂纹的产生和传播机理。研究表明，除了齿轮齿啮合引起的高频激励外，气体发生器转子的横向振动还将在CDBG上产生2倍激励。因此，在多源激励下，CDBG盘经历高频第五节点直径模式和低频摆动形振动模式。高频激励在齿轮齿的根部产生一个初始裂纹，并且裂纹在低频振动应力下传播，