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.