运载火箭/航天器耦合分支模态综合法(下)

将运载火箭作为主结构、航天器作为分支子结构,分别采用自由界面模态展开定理和固定界面模态展开定理,导出分支模态综合法,进行运载火箭/航天器组合模型响应分析。进而,采用界面约束模态质量的界面加速度,导出航天器载荷估计方法,这时的运载火箭与航天器连接界面可以是静定的或静不定的。当仅考虑连接界面是静定的情况,界面约束模态质量将退化为界面刚体质量,导出采用刚体界面加速度的航天器载荷估计的方法,这个方法所导出的公式与Chen的方法完全相同,而Chen方法的公式是由有限元法导出的。提出一种航天器载荷瞬态分析新技术:一个以前的运载火箭/航天器组合系统的载荷分析结果可以用来获得被相同的运载火箭发射的新航天器结构的动态载荷,这种方法比Chen的"恢复瞬态分析"方法更简便。

Branch modal synthesis method for coupled launch vehicle and spacecraft （Ⅱ）

In this paper the launch vehicle is considered as the main structure and the spacecraft is considered as a sub-branch. By using the free interface modal expansion theorem and the fixed interface modal expansion theorem the branch mode synthesis method for coupled launch vehicle and spacecraft is explored. The response analysis of combined model is carried out. New estimation for spacecraft loads is consequently derived based on the acceleration for the mass of the interface constraint modes. For this new estimation, the coupled interface can be either statically determinate or statically indeterminate. If only the statically determinate case is considered, the mass of interface constraint modes can be reduced to the mass of rigid-body. In this case, the proposed approximate method produces an identical formula to Chen＇s approach, which was developed alternatively using finite element method. A new transient analysis techniques of spacecraft load is proposed in the present study wherein the loads analysis results of a previous launch vehicle/ spacecraft system can be used to obtain the necessary information of a new spacecraft structure to be launched by an identical launch vehicle, rather than to recovery transient analysis＂ method of Chen is more convenient.