Effects of FLD Treatment on Vibro-acoustic Behavior of Cylindrical Shells

Structures with damping layers for controlling noise and vibration have been receiving increasing attention over the last decades. Analytical study is conducted in this paper to understand the characteristics of sound transmission through cylindrical shell with free layer damping (FLD) treatment. Using an infinitely long circular cylindrical shell subjected to a plane wave with uniform airflow in the external fluid medium, an exact solution is obtained by solving the Markus equations of FLD shells and acoustic wave equation simultaneously. Transmission losses obtained from the solution are compared with “modal-impedance method” in the especial case in which viscoelastic layer goes zero. Eventually, the numerical results show the effects of stiffness, damping loss factor and thickness of damping materials, different polymers and incident wave angles on TL curves.

Keywords:

Wave , Transmission loss , Viscoelastic , Free layer damping (FLD)