Vibro-acoustic computation of irregular cavities using a combined analytical-finite element approach with application to vehicle interior acoustics

A combined analytical-finite element approach is developed for more accurate representation and time efficient calculation of the acoustic frequency response function (AFRF) of a three-dimensional vehicle cavity with planar irregularities. In the proposed approach, finite element method is only used for determining modal properties of the two-dimensional irregular shape, while the analytical terms provide the modal properties of the overall three-dimensional volume. Modal superposition method is then applied to compute AFRF for panel excitations at critical suspension attachment locations. Results show that the proposed approach out-performs the direct finite element method in terms of computational time efficiency. Moreover, the AFRF obtained using direct finite element method with finer mesh converges to that predicted by the combined analytical-finite element approach. Analysis also reveals that although the irregularities increase the number of cavity modes coupled with structural panel modes, AFRF may have lower magnitude than that of the simpler rectangular cavity model.