Numerical study of noise transmission through functionally graded panels.

Abstract

Functionally graded panels are panels made of either functionally graded materials (FGMs) or functionally graded structures. FGM panels are traditionally used as thermal insulation barriers and they find applications in space and launch vehicles. Functionally graded structures include foams with continuous variations in pore size from one side to the other side. Such foams are incorporated as the core layer in sandwich panels. The latter is often used as partition walls in the building and transportation industries. In this study, we are concerned with the noise transmission characteristics of functionally graded panels. We developed an analytical model to derive the transfer matrix for the functionally graded medium. Using this model, we were able to make numerical predictions for sound transmission through functionally graded panels. The gradation parameter provides an additional degree of freedom in controlling the noise transmission characteristics. This is helpful in maximizing the noise reduction in panel design. Furthermore, our transfer matrix model applies to conventional discretely layered panels as well. In fact, the latter is just a special case in our modeling formulation. Numerical examples and results are presented and discussed.