Full-Frequency Vibroacoustic Modeling of a Ballistic Re-Entry Aeroshell and Validation through Diffuse Field Acoustic Testing

Abstract

During ballistic flight, a re-entry vehicle is subjected to high-level structural vibrations due to pressure fluctuations on its bounding surface. The aim of this work is to simulate this structural vibration response. The first step, which is not covered in this study, is the modeling of pressure fluctuations using aerodynamic simulation results. The second step is the simulation of the vibroacoustic response. In this study, the full-frequency vibroacoustic modeling of a metal shell representing a re-entry vehicle aeroshell is developed. The low-frequency response is computed using a FEM–BEM model while Statistical Energy Analysis is used for high-frequency behavior. The validation of these models is based on a ground experiment with controlled diffuse-field acoustic loading. A dedicated reverberation chamber was developed with loudspeaker excitation. The simulation results are compared with the experimental results. In the low-frequency range, simulation helps to understand the measured response spectra by highlighting the acoustic resonances and scattering phenomena. In the high-frequency range, an experimental identification of the damping loss factors and SEA modeling of each subsystem using an FE–SEA approach provides a predictive simulation of the vibration-response spectrum. In this application, FEM–BEM and SEA models are complementary in simulating full-frequency vibroacoustic responses.