Vibroacoustic Analysis of Laminated Composite L-shaped Acoustic Cavity using Multi-domain Coupled BE-FE Method

In this paper, vibroacoustic analysis of an L-shaped acoustic cavity comprising of rigid and laminated composite thin and flexible walls with opening has been performed by coupling multi-domain boundary element (BE) method with finite element (FE) method, where the cavity is divided into several domains with intermediate interface layers and the continuity conditions have been established at the interface. Finite element structural analysis of the interacting enclosure has been conducted to extract the mobility relationship between pressure and velocity at the interacting walls and apply that to the pressure-velocity multi-domain BE formulation of the interior acoustic cavity. Absorbent layers have been applied at multiple walls to investigate their effects on sound pressure levels at the boundary and inside the domain. Radiation impedance and admittance relationship have been implemented to model the opening and the absorbent layers at the boundary respectively. An in-house software incorporating the aforementioned features has been developed to solve practical vibroacoustic engineering problems of irregular-shaped cavities. The present program has been verified with analytical and experimental data available in the literature to ensure accuracy. It has been demonstrated that the shape of the acoustic domain along with the presence of opening alters the modal characteristics of the structure causing considerable modifications in the sound pressure level (SPL) pattern. Examples reveal that one can restrict the acoustic output at the resonant frequencies by suitably adding absorbents.