Dynamic Modeling And Vibration-Acoustic Response Analysis Of Satellite-Rocket Coupling Structures

Spacecraft suffers complex environment with the combination of vibration and noise during launch and service life. Accurate prediction of vibro-acoustic environment is an important basis for the spacecraft overall design, structural design, scheme and conditions of the ground test. In this work, satellite-rocket coupling system is taken as the object. Investigations on the following three respects were undertook. First, the dynamic modeling method of satellite-rocket coupling structure is explored in order to represent the dynamic characteristics of the structure efficiently and accurately. Then, the vibro-acoustic coupling prediction is proposed to reveal the response rules. Last, the acoustic transfer characteristic of satellite-rocket coupling structure is also discussed to provide guidance of the structural optimization and noise reduction.Accurate dynamic model is the basis of vibration-acoustic response analysis. First, the equivalent modeling method of clamp band in satellite-rocket coupling structure is studied. The axial stiffness of the clamp band is formulated under different axial preloads. The influence of axial stiffness on the natural characteristic is also discussed. Second, two equivalent methods including equivalent panel theory and sandwich theory are adopted to model the honeycomb sandwich plate. The analysis of sound transmission loss and radiation under plane wave is conducted using the two equivalent methods. Based on a combination of computational efficiency and sufficient accuracy, a modeling method is proposed for both the acoustic and structural analyses of large spacecraft structures.Accurate dynamic response is the basis of the dynamic strength evaluation. Based on the FEM-BEM approach, vibro-acoustic coupling analysis of the satellite-rocket structure is conducted under three types of random excitations:(a) random base excitation, (b) random acoustic excitation, and (c) both the random base and acoustic excitation. Response rules under different excitation are obtained. Furthermore, impact of the axial stiffness of the clamp band as well as vibration-acoustic coupling on the natural characteristic and dynamic response is also researched.Accurate external function is the basis of the structural optimization. Based on the Love theory, the sound transmission loss of the thin cylindrical shell is derived. Sound transmission loss and radiation of the rocket fairing is also obtained by FEM-BEM method. Factors which may affect the analysis of the sound transmission loss and radiation, such as wall thickness, number of ribs and flight angles, are also discussed. Meanwhile, the analysis of acoustic panel contribution is also carried out by acoustic transfer vector method. The distribution of the acoustic response in concerned frequency band and the contribution of the rocket faring panels in concerned frequencies are also studied. The research may have a great potential guidance for the structural optimization design and noise reduction.