Acoustic-structural coupling of the automobile passenger compartment

Renewed interest in reducing interior noise in transportation vehicles has motivated research in low frequency, structural-acoustic analysis. The internal sound field in the enclosed cavity is significantly affected by the acoustic modal characteristics of the cavity, by the dynamic behavior of the surrounding structure, and by the nature of the coupling of these two dynamic systems. The present work is intended to cast more light on the acoustic-structure interaction between the car compartment structure and the enclosed cavity. The system is studied using ANSYS finite element (FE) code. The modeling involved shell finite elements for the structure and three-dimensional (3D) acoustic elements for the cavity. The 3D FE modal analysis produced results visualizing the complex picture of acoustic-structure coupling. It was found that strong coupling between the thin-walled structure and the acoustic enclosure exists in the vicinity of any acoustic resonance. Also it was found that "combined" acoustic-structure modes of vibration exist in the vicinity of an acoustic resonance, which means that the coupled system manifests a new type of energy exchange.