Sound transmission loss of multi-layered infinite micro-perforated plates.

In this paper, the sound transmission loss (STL) of multi-layered infinite micro-perforated plates (MPPs) is studied. A prediction model for the STL of the multi-layered infinite MPPs is developed, where each MPP may or may not have a perforation, and the number of MPPs is arbitrary. When the frequency of interest is well below the critical frequency of the plate such that the effect of flexural vibration can be neglected compared to that of the inertia term, the mass is replaced by an equivalent complex mass.

Sound transmission loss of double plates with an air cavity between them in a rigid duct.

In this paper, the sound transmission loss (STL) of thin double plates with an air cavity between them in a rigid duct is considered using an analytical approach. The vibration motion of the plate and sound pressure field are expanded in terms of an infinite series of the modal functions. Under the plane wave condition, a low frequency solution is derived by including the first few symmetric modes.

Dispersion suppression of guided elastic waves by anisotropic metamaterial.

This investigation presents a method to engineer a metamaterial exhibiting the desired anisotropic wave behavior with the specific applications toward the dispersion suppression of elastic guided waves. In the proposed approach, effective anisotropic properties required for dispersion suppression were first determined. Then the slowness curves for the metamaterial were used to find the specific unit cell configuration through inverse design.