ACOUSTICAL BEHAVIOUR OF GRP PANELS FOR MARINE APPLICATION

Nowadays the noise reduction onboard yachts is an important aspect of ship design. This work focuses on the sound transmission properties of GRP (glass reinforced plastic) structures that are widely used in yacht and small craft construction. One of the main acoustical parameters adopted to measure the attitude of a panel to transmit sound is the transmission loss that estimates the amount of sound reduction that a partition imparts to an acoustic wave impinging on it. An experimental test campaign has been carried out in a small acoustic facility developed by Department of Aerospace Engineering of University of Naples Federico II on a set of GRP panels commonly used in craft construction. Tested panels were different for lay-up and manufacturing process. At a first stage, measured acoustical behaviour has been compared at low-medium frequencies with predictions performed by a finite element based procedure. In order to extend the frequency range of analysis, for some panels energy based models have been developed too. A good agreement between numerical and experimental behaviour has been obtained and mass law region and coincidence effect have been correctly identified.