全尺寸航天器振动台多维振动试验的天地一致性研究(下)

The consistency of dynamic responses of a full scale spacecraft between ground tests and its space missions(Ⅱ)

地面振动试验中的全尺寸航天器响应与在天上全箭振动时的航天器响应是否一致的问题,即振动试验的天地一致性问题。通常,航天器振动试验方法无法同时反映航天器在天上全箭振动时航天器和运载火箭(简称器箭)界面的加速度条件和器箭界面的安装边界条件,因而无法保证其实验结果的可靠性。对针对这一问题,于全尺寸航天器而言,如果让航天器和振动台(简称器台)界面的加速度等于在天上全箭振动时的器箭界面的加速度条件,就能同时自动满足航天器器台界面安装边界条件,由此就能求得全尺寸航天器在振动台振动试验中的解析解,精确等同在天上全箭振动中航天器振动响应。首先应用动态实验仿真技术,导出天上全箭振动响应模型及其解析解,包括:器箭界面的加速度条件和航天器内部加速度响应。然后让全尺寸航天器与振动台的界面加速度等于全箭振动中导出的器箭界面加速度条件,由此就能对全尺寸航天器振动台多维振动试验进行仿真,给出在振动台振动试验中全尺寸航天器响应的解析解结果,可以证明在振动台多维振动试验中全尺寸航天器响应的解析解等于在全箭振动中航天器响应的解析解。这一研究成果,为采用全尺寸航天器振动台多维振动试验方法来精确再现在天上全箭振动中航天器多维振动力学环境提供了完整的理论依据和实践指导。

This paper investigates the dynamic response of a Full Scale Spacecraft （FSS） in ground tests and in space missions. The consistency between the responses obtained from ground tests （while the spacecraft is mounted on a shaker） versus its actual response in space （while the spacecraft is mounted on a launch vehicle）is explored. This is so called ground-space consistent problem. Considering the interface between FSS and its holding devices （either launch vehicles or shakers）, modem ground testing technique doesn＇t guarantee the interface accelerating condition （IAC） and the interface boundary assembling condition （IBAC） to be satisfied at the same time. Therefore it cannot guarantee the accuracy of its results obtained from ground tests. Facing the problem, the paper reveals that, by setting IAC between the FSS and the shaker to the same value as the IAC between the FSS and the launch vehicle, the corresponding IBAC would be satisfied automatically. Therefore using the proposed multidimensional test approach, the dynamic response of FSS in space can be simulated accurately on ground. To prove the hypothesis, first, the paper derived the dynamic response of the Full Scale FSS in space （mounting on a launch vehicle） in an analytical form. This analytical result includes the IAC between the spacecraft and the launch vehicle, as well as the actual response of the spacecraft in space Second, by setting IAC between the FSS and the multidimensional shaker to the same value as the IAC between the FSS and the launch vehicle, the dynamic response of the FSS on shaker were also simulated analytically. The dynamic response obtained in the second step is compared to the internal response obtained in the first step to validate the consistency of the two results. This result shows that the proposed ground tests on a multidimensional shaker can indeed produce the actual response of FSS in space when mounted on a launch vehicle. The new development will be a theoretical basis and practical guidance for future ground based multidimensional dynamic test of FSS.