Vibro-acoustic analysis of aerospace structures and issues with the available commercial prediction tools

The results of vibro-acoustic modeling using the boundary element method (BEM) that predicts the acceleration responses at critical locations and at the interfaces of selected test articles are discussed. High fidelity acoustic tests were performed in a couple of cases and the results are used to validate the BEM predictions. The accuracy of the BEM and its ability to correctly predict the acceleration responses of lightweight structures are discussed in some detail. Also a combined system level BEM, consisting of structures very responsive to acoustic pressures, and force-limited base shake random vibration analysis was performed. We will discuss how these results may be used to derive random vibration specifications for the purpose of qualifying large and lightweight structures for flight. In this paper, we also discuss the commercially available vibro-acoustic tools that are used to predict the acoustic transmission losses and vibration responses of flight structures for lift-off (assumed to be diffuse) and transonic (turbulent boundary layer) acoustic fields. The pros and cons of using the statistical energy analysis, finite element analysis, BEM, and newly developed hybrid methods within these vibro-acoustic tools are discussed in some detail.