Sound insulation of a lightweight lattice sandwich panel

In this study, an analytical approach based on the Reissner sandwich panel theory is presented for the analysis of sound insulation properties of a lightweight sandwich panel with lattice cores. A comparison of the sound insulation of the sandwich panel predicted using the analytical solution and finite element analysis shows that by ignoring the shear stiffness of face plates of the sandwich panel can lead to a deviation in the predicted sound insulation result, exemplified by the frequency difference of the valleys in the STL of the panel. An equivalent shear energy principle is then adopted to render a revised equivalent shear stiffness of the sandwich panel by including the contribution of the face plate shear stiffness. It is shown that the analytical STL prediction of the panel using the equivalent shear stiffness matches quite well with that using finite element analysis under a normal incident sound wave excitation. There is a deviation in the results when the sandwich panel is under an oblique sound wave excitation due to the isotropic assumption in the evaluation of the equivalent shear stiffness of the lattice core in the analytical solution. A sound insulation experiment is also carried out in the study to verify the theoretical prediction result of the sandwich panel.