Abstract: Accurate calculation of the vibration characteristics and fatigue life of the distributed connection structures between reusable spacecraft and engines was crucial for ensuring the safe operations of aerospace transportation systems. Focusing on the distributed connection structures, the feasibility of experimental validation for finite element simulation methods was demonstrated. The vibration characteristics of the distributed connection structures were explored in both of the time and frequency domains, and the fatigue lives of the structures were calculated under different operating conditions. The findings reveal a commendable concordance between the finite element results of the hysteresis curve for the connection structures and experimental observations. Under cyclic loading at different excitation frequencies, the connection bolts manifest stress increments or decrements, indicative of fatigue effects. The distributed connection structures elicit significantly heightened responses at the 1st and 5th natural frequencies. Decreasing the excitation magnitude substantially augments the fatigue lives of the connection structures, and an escalation in bolt pre-tightening forces is found to enhance fatigue lives as well. However, an increase in excitation frequency only marginally diminishes the operational lifespans, while the cyclic lifespans persist within the same order of magnitude. Furthermore, following the introduction to thermal and creep effects, the distributed connection structures may withstand a maximum of only five thermal cycling loads.

Key words: reusable aircraft, distributed connection structure, vibration characteristics, fatigue life

摘要： 准确计算重复使用飞行器与发动机之间分布式连接结构的振动特性及疲劳寿命是确保航天运输系统安全运行的前提和基础。以分布式连接结构为研究对象，用实验验证了有限元仿真方法的可行性，从时域和频域探究了分布式连接结构的振动特性，计算了不同工况下分布式连接结构的疲劳寿命。研究结果表明，连接结构滞回曲线的有限元结果与实验结果吻合较好；在不同激励频率的循环载荷作用下，连接螺栓发生应力增长或应力衰减，出现疲劳效应；分布式连接结构在第1、第5阶固有频率处激发较大的响应；降低激励幅度能够极大延长连接结构疲劳寿命，增大螺栓预紧力也能够延长疲劳寿命，但增大激励频率只能够稍微缩短时间寿命，周期寿命仍在同一量级上；引入热和蠕变影响之后，分布式连接结构最多只能承受5次热循环载荷。

关键词: 重复使用飞行器, 分布式连接结构, 振动特性, 疲劳寿命