Determining excitation forces acting on the interior surface of an enclosure. Part I: Theory

Abstract

Part I of this paper presents analytic solutions for reconstructing the excitation forces that act on the interior surfaces of a finite solid rectangular enclosure with the fluid loading effect taken into consideration, given vibroacoustic data in the exterior region. The reason for selecting a simple structure is to facilitate the reconstruction of excitation forces. To validate these analytic solutions, we apply the reciprocity principle and demonstrate that when the resultant excitation forces are used to excite the enclosure from the inside, the same vibroacoustic responses in the exterior region in exterior region can be obtained. To illustrate this point, we consider the case in which the top panel of a rectangular box is connected to the side walls through simply-supported boundary conditions, and the rest surfaces are rigid. The top surface of this box may be excited into vibrations by any type of excitation forces from the inside with the fluid loading effect taken into consideration. Note that for arbitrarily shaped structures under arbitrary boundary conditions, numerical solutions can be obtained. Therefore, it is possible to determine the excitation forces acting inside an enclosure based on the vibroacoustic information collected in the exterior. The knowledge of the excitation forces is critically important, because it can lead to optimal mitigation strategies to mitigate undesirable noise and vibrations.