Assessment of the validity of statistical energy analysis and transfer matrix method for the prediction of sound transmission loss through aircraft double-walls
Résumé
The accuracy of sound transmission loss (TL) predictions of aircraft double-walls using transfer matrix method (TMM) and statistical energy analysis (SEA) is examined in this paper. The studied system is composed of: (1) a laminate composite skin panel whose critical frequency is around 4000 Hz, (2) an air gap partially filled with a fibrous layer and (3) a sandwich trim panel with critical frequency around 2500 Hz. The structure is submitted to a diffuse acoustic field in the frequency range from 100 Hz to 10 kHz. A transfer path analysis shows that for this structure, including a highly-radiating trim with a low critical frequency, the resonant transmission through the cavity between panels is dominant over a large frequency range. This transmission path is not accounted for in the TMM formulation, resulting in an overestimation of the transmission loss compared to measurements and SEA computation. On the other hand, for practical purposes, both approaches are able to predict the impact in the TL of modifying the parameters of the skin panel for frequencies below its critical frequency.
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