Numerical analysis of acoustic radiation properties of laminated composite flat panel in thermal environment: A higher-order finite-boundary element approach

Abstract

In this article, the vibration-induced acoustic responses of laminated composite flat panels subjected to harmonic mechanical excitation under uniform temperature load are investigated numerically. The natural frequencies alongside corresponding modes of the flat panels resting on an infinite rigid baffle are obtained by using finite element method in the framework of the higher-order shear deformation theory. A coupled finite and boundary element formulation is then employed to acquire the acoustic responses. The governing equation for the sound radiaiton from the vibrating structures is derived by solving the Helmholtz wave equation. The vibration and acoustic responses are computed by using the present scheme via an in-house computer code developed in MATLAB environment. In order to avoid any excess thermal loading conditions first, the critical buckling temperature of the panel structure is obtained and authenticated with the benchmark values. Further, the sound power levels for isotropic and laminated composite panels are computed using the present scheme and validated with the existing results in the published literature. Finally, the influence of lamination scheme, support conditions and modular ratio on the acoustic radiation behavior of laminated composite flat panels in an elevated thermal environment is studied through various numerical examples. The thermal load is found to have substantial influence on the stiffness of the panels and the peaks in the free vibration responses tend to shift to lower frequencies for higher temperatures. It is also inferred that the panels radiate less efficiently whereas the overall sound pressure level is found to follow an increasing trend with increasing temperature.