Cork/aluminium double-layer sandwich panels under impact loading for lightweight ship structures

To meet the reduction targets of greenhouse gas emissions by highly polluting vessels such as cruise ships, several strategies are possible: the introduction of new fuels (i.e. LNG, hydrogen and biofuel), the installation of more efficient engines, the electrification of the propulsion systems, the lightening of the structures, the energy efficiency improvement of the auxiliary services (i.e. air conditioning). In particular, vessels weight reduction can be achieved by introducing new materials. The aim of this work was to manufacture an innovative laminate, which comes from the combination of a cork layer and an aluminium honeycomb sandwich, intended to provide an eco-friendly and lightweight solution for structures potentially destined to marine applications, such as ship decks, hulls or cabins' construction. The suggested solution is expected to combine several functions and properties, such as low density and thermal and acoustic insulation - which potentially influence propulsion and auxiliaries fuel consumption-as well as good mechanical performances. The investigation was particularly focused on the potentialities offered by the cork layer, traditionally addressed at insulation purposes, in supporting and enhancing the impact-absorption capabilities of the aluminium honeycomb structure, especially in view of the potential marine applications which often suffer from low-velocity impact events. Having a dual function: (i) to lighten the superstructures and (ii) to promote the thermal and acoustic insulation, by thus influencing, respectively, propulsion and auxiliaries fuel consumption. For instance, the suggested solution could be used for cabins' construction. In the present work, the energy absorption capabilities of the new lightweight structure were evaluated by means of low-velocity impact tests. An excellent response, comparable to that of double-layer aluminium honeycomb sandwich panels, was observed, suggesting that the new structure is a promising and sustainable alternative for marine constructions.