声振环境下航天器结构应力时程分析

Analysis of Time History of Stress on Spacecraft Structure in Vibro-acoustic Environment

航天器发射段严酷的声振环境可能造成薄壁结构上产生一定的裂纹损伤,评估这种裂纹损伤的重要前提是获得结构最大应力的时间历程。针对该问题提出一种航天器结构声振环境下应力时程分析方法。首先基于统计能量分析得到薄壁构件空间平均弯曲应力功率谱,然后基于应力翻倍原则考虑边界条件对应力集中的影响,获得薄壁构件上最大应力的功率谱,最后用随机相位正弦波叠加的方式对最大应力的时间历程进行模拟。针对某载人航天器,采用该方法计算其在发射主动段声振环境下的结构响应,分析其响应特性,得到了密封舱薄壁球底上法兰盘附近最大弯曲应力的时程,并采用雨流计数法对其循环计数特性进行了分析。研究结果可为航天器薄壁结构裂纹损伤评估提供参考。

The severe vibro-acoustic environment during launch may cause crack damage to thinwalled structures of a spacecraft,and the prerequisite of evaluating such structure damage is the time history of the maximum stress on the structure. An approach analyzing the time history of the spacecraft structure under vibro-acoustic load was presented. First,based on statistical energy analysis,the power spectrum of the spatially averaged flexural stress of thin-walled structure was obtained.Then,the stress concentration due to boundary conditions was accounted for by using the Stress Doubling Rule. Lastly,the random time history of the maximum stress was simulated through the superposition of a series of sinusoidal waves with random phases and amplitudes derived from the spectrum previously obtained. The approach was applied to a manned spacecraft subject to vibro-acoustic load during launch,the time history of the maximum stress near flanges on the habitable module ＇s spherical dome,was obtained. The approach proposed offers a basis for the crack damage evaluation of thin-walled structures of spacecraft.