## 6 Conclusions  
This work is a step towards the simulation of the vibroacoustic response of a ballistic vehicle during flight. Beyond the difficulties of characterizing in-flight pressure fluctuations, which are not addressed in this study, a detailed vibroacoustic model of the vehicle is needed. A test structure representing an aeroshell was modeled using finite elements and Statistical Energy Analysis. This model was validated through diffuse acoustic field testing. A dedicated experimental setup in a reverberant chamber was developed. In the low-frequency range, the test-simulation comparison highlights the need to model the air volume surrounding the structure to consider internal acoustic resonances and scattering effects. With BEM modeling of the surrounding air volumes, the simulation results are close to the experimental data, with a maximum 6 dB difference. In the high-frequency range, two key steps were necessary to set up the SEA model: experimental identification of the Damping Loss Factor using a dedicated ground experiment and the use of a periodic FE-SEA method for the modeling of each subsystem and the computation of the Coupling Loss Factors. The results obtained with this model are in accordance with the mean responses in each subsystem. A slight underestimation of the response level in the upper side of the envelope was observed (\(-3.8\) dB); yet, this simulation-test agreement is sufficient to validate the model. The FEM-BEM and SEA results are complementary to obtain the full-frequency vibroacoustic response. For each simulation point studied, the estimated high-frequency response is the average value in the subsystem to which the point belongs, calculated using the SEA. Good test-simulation agreement was observed with a maximum difference of \(-4.1\) dB. For the particular structure under study, the boundary between the FE-BEM and SEA frequency domains was set at 2200 Hz. The full-frequency test-simulation comparison shows that this boundary is well-suited for the envelope and is slightly low considering the bottom of the structure. The model could thus be improved by including more modes in the FEM-BEM analysis and by shifting the boundary with the SEA domain towards high frequencies. Another improvement could be the introduction of an additional mid-frequency model, such as an FE-SEA model. Regarding the industrial application, the full-frequency model described meets the need to forecast dynamic responses. **Author Contributions:** Formal analysis, M.C. and H.V.C. ; Investigation, M.C., H.V.C. and B.A. ; Methodology, M.C., H.V.C. and B.A. ; Writing--original draft, M.C. and H.V.C. ; Writing--review & editing, B.A. All authors have read and agreed to the published version of the manuscript. **Funding:** This research received no external funding. **Data Availability Statement:** Not applicable. **Acknowledgments:** The authors acknowledge the CEA/CESTA teams involved in this project: the team that developed the acoustic experimental setup, the team that designed and engineered the test structure and the team that ran the experiments. The authors also acknowledge the Polytec team that performed the laser vibrometer measurements and the Dassault System--Wave6 team that helped with the modeling.