Experimental and Numerical Analysis of Absorber Materials for Steel Decks

Nowadays, comfort is becoming the principle goal for designers. But what does comfort onboard really mean? It is possible to define it as a sense of physical or psychological ease, often characterized as a lack of hardship, and it is therefore a subjective sensation. In fact, the perception of a comfort condition is due to a complex mechanism in which the different senses are involved and interact with each other. When trying to improve the comfort onboard, it should be considered that the interaction between the environment and the people on board is realized through the perception of stimuli related to hearing (noise), the nose, breathing and transpiration (air quality and temperature), the view (aspect of the environment), physical contact (vibration) and the sensation of movement of the body in space (ship motions). Until now, the most important Classification Societies impose severe rules and regulations only for the evaluation of noise and vibration maximum levels for different zones. Many other aspects that influence the comfort on board are currently under study. The surge to provide the market with more comfortable products gave rise to high awareness for the analysis of sound transmission and absorption of the main materials used in shipbuilding. There are two parameters for describing the behavior of sound absorber materials: Transmission Loss (TL) and Insertion Loss (IL). For metals, in particular steel, it is well known that the interior damping is very low. In contrast, there are so-called viscoelastic materials which show high dissipation of mechanical energy. In this paper, a measurement campaign on real scale is described for investigating the dynamic behavior of different materials used to absorb vibration and sound propagating through steel decks. A comparison of TL and IL values obtained from experimental data and from finite element analyses is then carried out.