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

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