Aeroelastic analysis of rocket structural vibrations

Studies of structural vibrations have always been a concern for researchers and engineers because it may cause the structure fatigue or failure. This study considered a free-free beam with cubic nonlinearities, which subjected to the distributed load with the wind pressure and its associated unsteady aerodynamic force. There is a wide range of applications of this study such as rocket structure, satellite, etc.Thepurpose of thisresearch is to find whether there is an internal resonance (I.R.) in the system. We analyzed this nonlinear system by the method of multiple scales (a perturbationtechnique);the equations of motion in different time scales were transferred into linear equations. Wethen utilized thefixed point plots (steady state frequency response) to examinethe internal resonance of the system. From the results of the fixed point plots, we found that there exists energy transferbetween y and zdegree of freedom (DOF) of the beam in specific conditions, as shown in Fig. 1. This phenomenon might cause the system occur primary resonance (P.R.), which was the special case of the internal resonance. Fig. 1 shows that when the dimensionless wind pressure q~ equals 8(Mach number = 2), the primary resonanceoccurs. When the y-DOF is excited, the z-DOF has larger response amplitude than the y-DOF. Finally, we used the numerical method, fourth-order Runge-Kutta method, to verify the results of frequency response and the internal resonance.Beihang University, Beijing, P.R.China.補正完