基于修正的Craig-Bampton法的大长径比助推器分离特性研究

在芯级周围布置助推器是提升运载能力的有效手段。对于长径比较高的助推器，结构呈现明显的局部弹性效应，这将对助推器分离的安全性产生影响。针对传统Craig-Bampton方法无法适用于大范围运动弹性体的不足，本文采用修正的Craig-Bampton法获得系统的正则化模态，使研究对象的所有模态与频率一一对应，实现分离体大范围刚体运动与弹性变形的有效耦合。基于该方法开展柔性多体动力学仿真，获得了不同模态阶数和结构刚度的弹性助推器分离系统的分离特性。研究结果表明，与传统的刚体模型相比，考虑助推器弹性效应的分离动力学模型更加贴近真实飞行情况。基于此，获得了各阶模态和结构刚度对分离安全边界的影响规律，其中以一阶横向模态最为敏感。通过研究弹性助推器的分离特性，为运载火箭助推器分离系统的工程实际应用提供理论参考和研究支撑。

Separation performance of the boosters with large length/diameter ratio based on improved Craig-Bampton method

The strap-on launch vehicle is widely adopted in order to increase the launching capability.The boosters with large length/diameter ratio presents obvious flexibility,which will affect the separation safety.The Craig-Bampton method couldn''t sufficiently cover the flexible body''s dynamic response characteristic.In this paper,the improved Craig-Bampton method will be used to get the normal modes,to match the frequencies,and couple the rigid body motion could couple with the elastic deformation.Based on this method,the boosters'' separation characteristics in different number of modes and stiffness are studied.The results show that the elastic model is much closer to the reality than the rigid one.The sensitivity of the safe separation boundary of modes and stiffness is determined,and the first bending mode is found to be most sensitive.This work will provide a reference and theoretical support for the design of engineering application.