Vibration Responses for Plate-Shell-Plate Combined Structure in Reusable Rocket During Launch and Return Phases

This paper focuses on the key load-bearing components of reusable rockets and establishes a semi-analytical dynamic model for plate-shell-plate combined structures. Based on the first-order shear deformation theory, the model fully considers external excitation and damping dissipation effects. Combining the energy method with the Rayleigh–Ritz method, the steady-state responses of discrete governing differential equations are solved, and numerical examples are adopted for model verification. This study systematically investigates the vibration characteristics of the structure during launch and return stages, and further discusses the influences of excitation location, geometric parameters, material properties, excitation amplitude and damping on structural dynamic responses. The results demonstrate that excitation in the launch stage induces localized resonance and asymmetric coupling effects, whereas excitation during the return stage leads to uniform energy propagation inside the shell with symmetric response distribution. Additionally, increasing the length-to-radius ratio or elastic modulus can raise the natural frequency and increase the number of resonance peaks, while excitation amplitude and damping mainly affect the resonance response magnitude. The research outcomes can provide a solid theoretical basis for vibration suppression and structural parameter optimization of reusable rockets, and offer technical references for the structural design of reusable rocket structures under multi-flight-stage conditions.