This paper presents a modeling technique to study the vibroacoustics of multiple-layered viscoelastic laminated beams using the Biot damping model. In this work, a complete simulation procedure for studying the structural acoustics of the system using a hybrid numerical model is presented. The boundary element method (BEM) was used to model the acoustical cavity, whereas the finite element method (FEM) was the basis for vibration analysis of the multiple-layered beam structure. Through the proposed procedure, the analysis can easily be extended to another complex geometry with arbitrary boundary conditions. The nonlinear behavior of viscoelastic damping materials was represented by the Biot damping model taking into account the effects of frequency, temperature, and different damping materials for individual layers. The curve-fitting procedure used to obtain the Biot constants for different damping materials for each temperature is explained. The results from structural vibration analysis for selected beams agree with published closed-form results, and results for the radiated noise for a sample beam structure obtained using a commercial BEM software are compared with the acoustical results of the same beam by using the Biot damping model. 1. Introduction The traditional designs of free-layer, constrained-layer or sandwich-layer, damping treatment using viscoelastic materials have been around for over forty years. Recent improvements in the understanding and application of the damping principles, together with advances in materials science and manufacturing, have led to many successful applications and the development of patch damping and multiple-layered damping structures. The key point in any design is to recognize that the damping material must be applied in such a way that it is significantly strained whenever the structure is deformed in the vibration mode under investigation. Numerous researchers have successfully implemented the passive constrained layer (PCL) and active constrained layer (ACL) systems. In 1959, Kerwin [1] and Ross et al. [2] presented a general analysis of viscoelastic material structure. The damping was attributed to the extension and shear deformations of the viscoelastic layers. Ditaranto [3] developed sixth-order equations of motion in terms of axial displacements and developed a closed-form solution. Mead and Markus [4] extended the sixth-order equations of motion for transverse displacement to include various boundary conditions. A paper by Rao [5] presented the equations of motion of viscoelastic sandwich beams with
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