Viscoelastic-acoustic response of new polymeric matrix composite shells considering cavity resonances using a new approach: Layered viscoelastic model

摘要

Here, for the first time, acoustic scattering and noise reduction of the sandwich cylinders made of a new type of polymeric matrix composites which porosity changes gradually in the thickness direction are examined. The porosity distribution and relaxation time are important characteristics of these materials. In the new approach as known the layered viscoelastic model, it is assumed that the core is composed of an infinite number of viscoelastic layers and the mechanical properties of layers are different from vicinity layers. Considering the frequency dependency, the Havriliak-Negam model that can predict the viscoelastic behavior of each layer is used to describe the rheological response. According to the role of rotary inertia and shear deformation, the governing equations of layers are obtained using the 3-D theory of elasticity. The transfer matrix method is applied that consists of a matrix of global transfer, which is composed as the product of the matrices of local transfer by employing the stress and displacement components continuity at the interfaces of vicinity layers. For evaluation of the present study, results are compared with other researchers' results. Eventually, the influences of the polymeric matrix, pore distribution, porosity coefficient, and power index on vibroacoustic behavior are investigated.