Vibroacoustical modeling and modal analysis of a double wall panel

Abstract

In this paper results are reported of analytical and experimental vibroacoustical modal analysis of a double wall panel. Both mechanical vibrations of panel walls as well as the modal behavior of acoustical field in cavity were identified. Special interest was focused on identification and modeling of interaction and coupling between vibratory behavior of the walls and acoustical field in the cavity and their influence on drop of the transmission loss of the panel, as measured in the laboratory. The identification was carried out using a set of combined vibratory and acoustical frequency response functions measurements as response due to random noise force and controlled volume velocity source. The identified global complex modes of the panel and an estimated model of the panel employing general parameters were of high quality. It was confirmed by very good orthogonality of the identified vibratory and acoustical mode shapes and high correlation values between the measured and synthesized frequency response functions. This result provides a robust basis for the numerical study of the transmission behavior of the panel in the low-frequency range. Application of this result on optimum placement of force actuators to increase of transmission loss over a lower-frequency range by means of active noise and vibration control will be presented.