Finite Element Method and Dynamical Energy Analysis in Vibroacoustics - A Comparative Study

Kurzfassung

Future aircraft concepts utilizing innovative lightweight structures and novel propulsion concepts are a necessity for long term sustainable air travel. While the development is mainly driven by lightweight design and fuel-efficient propulsion, these concepts may pose new challenges for the vibroacoustic analysis of cabin structures and the associated noise impact on passengers. Finite Element (FE) models derived from aircraft pre-design data are not optimized for use in acoustic analyses, i.e. the mesh typically is too coarse to provide meaningful results. At the same time, setting up Statistical Energy Analysis models for this specific purpose is adding another time-consuming step. An alternative possibly exists in the Dynamical Energy Analysis (DEA). This method allows to calculate the acoustic behavior of thin-walled structures in higher frequency ranges simply using existing FE meshes. In this paper an experimental lightweight aluminum structure and its respective FE model is investigated for a frequency range up to 5000 Hz. A comparison in terms of vibrational energy between DEA, FEM and measurement results is presented. Finally, a lower-bound frequency range is identified in which DEA and FEM correlate and thus allow a substitution for further simulations at higher frequencies. To ensure the transferability of the results to structures of other dimensions and materials, frequency scale factors based on analytical equations are derived.