Vibroacoustic response analysis of functionally graded double-wall configurations under thermo-mechanical excitations

Double-wall configurations made of advanced composite materials are widely used in aerospace systems and are often subjected to dynamic loadings in thermal environments. Under such conditions, it is important to analyse their vibroacoustic behaviour from both structural and noise control perspectives. The present research work investigates the vibroacoustic response of double-wall configurations made of functionally graded (FG) and laminated composite materials subjected to thermo-mechanical excitation. A coupled numerical model is therefore developed by combining the finite element (FE) method for structural panels with the boundary element (BE) method for the acoustic domain. Thermal effects are introduced through a prescribed temperature gradient across the thickness of the FG panel. Geometric non-linearity due to thermal loading is incorporated in the first-order shear deformation theory-based displacement model through Green-Lagrange non-linear strains. The acoustic cavity is modelled using the BE method and coupled with the structural non-linear strain-based FE model to compute the vibroacoustic response. The results indicate that increased thermal loading enhances structural-acoustic interaction, resulting in higher vibroacoustic energy transmission, with the radiated sound power increasing by up to 50 dB at the first coupled modes compared to ambient conditions. Symmetric laminate configurations in the interior panel exhibit reduced sound radiation characteristics, highlighting their effectiveness in controlling energy transmission under thermo-mechanical conditions. It is also noted that the material gradation of the excited panel primarily affects stiffness rather than acoustic energy transmission.