Numerical and Experimental Assessment of the Transmission Loss of Honeycomb Sandwich Panels

Sandwich structures are more and more employed in the transport industry due to their high stiffness-to-weight ratios. However, such properties are also responsible for their poor vibroacoustic performance. The understanding and the ability of predicting the vibroacoustic behaviour of such structures is therefore becoming of crucial importance. The present work focuses on the prediction of the Transmission Loss (TL) of honeycomb sandwich panels. Firstly, a numerical model of a honeycomb sandwich panel is developed. Starting from the nominal material data the model is tuned to match the natural frequencies and mode shapes obtained performing an experimental modal analysis on an actual honeycomb sandwich panel with carbon fibre laminate skins. Damping Loss Factor (DLF) measurements are performed according to the reverberation time method to cover a broad frequency range, results are furthermore compared against modal analysis estimations. Predicted material data and experimental DLF are employed in a sandwich panel model based on the Transfer Matrix Method (TMM) combined with a windowing correction to consider the panel finite dimensions. The effectiveness of the approach adopted is confirmed by the comparison of the numerically predicted TL and the TL measured in a double reverberant room.