Determining excitation forces acting on the interior surface of an enclosure. Part II: Numerical simulations

Abstract

Part II of this study presents numerical simulations of reconstructing the excitation forces acting on the interior surface of an enclosure, based on the vibroacoustic information collected in the exterior region. Various types of excitation forces such as distributed, line, and point forces are considered. Moreover, fluid loading inside the enclosure is considered in the numerical simulations. Analytical proofs show that fluid loading has no impact on excitation forces, but has significant impacts on structural vibrations. This is especially true when the density of fluid medium inside an enclosure is high. Results demonstrate that when excitation forces are continuous, the accuracy in reconstruction may be very high. When excitation forces contain abrupt changes or discontinuities, for example, line and point force, the accuracy in reconstruction may be significantly reduced. This is because many expansion terms are required to properly describe the discontinuities of excitations. On the other hand, discretization grids are fixed a priori. When fixed discretization grids are used together with an increasing number of expansion terms, aliasing may occur that may completely distort the reconstructed excitation forces.