Abstract: Blade loss is the key factor of airworthiness certification for high bypass ratio turbofan engine，and is the key issue which affects the structural integrity and safety. Based on the impact load caused by blade loss，research on dynamic response mechanism and safety design method of rotor structure system are studied. The dynamic model of the high speed flexible cantilever rotor system is established，which include the characteristics of stiffness and mass distribution，load transfer characteristics，and coupling characteristics of the rotor and stator. For the sudden unbalance excitation and large unbalanced rotor system，the rotor vibration and bearing reaction force response in the process of continuous impact rubbing are proposed by means of theory and experiments. The results show that，the support structure is crucial to the survival of the engine structure system. The variable bearing stiffness design method is presented to improve the safety in engine level. While protecting the integrity of the bearing and avoiding the shaft jammed，this method reduces the rotor vibration response. The engine level numerical simulation of the whole process of blade loss shows that the method reduces the max bearing load by 46%，which verifies the effectiveness of the safety design strategy.

Key words: Aero engine；Rotor system；Impact excitation；Safety；Structural design

摘要： 叶片丢失是高涵道比涡扇发动机适航认证的关键，是影响结构完整性和安全性的关键问题。针对叶片丢失产生的冲击载荷激励，开展了转子结构系统的动力响应机理和安全性设计方法研究，为发动机结构完整性设计提供支撑。建立了高速柔性悬臂转子系统动力学模型，考虑了刚度质量分布特征、载荷传递特征、转静件耦合特征。通过理论和试验，揭示了突加不平衡激励和超大不平衡转子受到持续的冲击碰摩作用过程中，转子振动响应和轴承支反力响应特征。结果表明，支承结构是影响系统存亡的关键环节。提出了提高整机系统安全性的变支承刚度设计方法，在保护轴承完整性、避免抱轴的同时，也降低了系统的振动响应。基于整机模型的叶片丢失全过程的算例仿真分析表明，该方法使支点所受峰值载荷降低了46%，验证了安全性设计策略的有效性。

关键词: 航空发动机；转子系统；冲击激励；安全性；结构设计