轴向载荷对大长细比导弹稳定性的影响研究

大长细比飞行器的刚性模态和弹性模态极易发生耦合失稳现象。轴向载荷作用下其结构刚度特性会发生变化，进一步降低其稳定性。使用有限元方法分析了大长细比导弹在轴向载荷作用下的结构刚度特性。采用当地流活塞理论计算弹性体变形的气动力，耦合结构运动方程，基于模态坐标在状态空间内实现结构运动方程的特征值分析和时域求解，研究轴向载荷对大长细比导弹稳定性的影响。研究发现：大轴向过载作用下，大长细比导弹的刚性模态和弹性模态将出现耦合失稳，且随着轴向过载的增加，弹体的结构刚度特性下降，失稳速度降低。

Analysis on Stability of a Slender Missile under Axial Loads

For slender missile, there is a potential coupling effect between rigid mode and elastic mode, which makes the system unstable. As the axial loads have a negative effect on the structural stiffness property, the stability of the system gets worse further. A finite element method is used to study the influence of the axial loads on the structural stiffness property of missile. The local piston theory coupled with the structural motion equations is developed to analyze the stability of a slender missile in state-space. It is shown that the rigid mode and elastic mode of the slender missile couple together under high axial loads，resulting in the system instability. Moreover, as the axial acceleration loads increase, the structural stiffness of the missile reduces, and the critical instable speed falls.