IMPACT PERFORMANCE OF COMPOSITE SANDWICH STRUCTURE UNDER HIGH VELOCITY IMPACT

Composite sandwich panels are well known for their relatively high stiffness over weight ratio and have been increasing utilized in various applications where the weight of the structure is a key design concern, e.g. in aircraft and aerospace components. However, these structures are vulnerable when subjected to a transverse impact loading. In this paper, the impact performance of composite sandwich structures with foam core is investigated. In particular, the idea of multi-layering the core by foam layers of different density and its effect on the energy absorption under low and high velocity impact is of interest. In this study, composite sandwich panels made of Glass Fibre Reinforced Polymers (GFRP) for skins and PVC foam for the core are used. Two different arrangements of foam core are considered: uniform core (80/80/80 kg/m(3)) and graded core (100/60/100 kg/m(3)). Both of these core arrangements have the same areal density. Low (up to 5 ms(-1)) and high (up to 200ms(-1)) velocity impact tests were performed using a drop tower and a gas gun respectively. In-plane and out-plane properties of composite sandwich samples were measured employing 2-D and 3-D Digital Imaging Correlation (DIC) methods. The results indicate that the composite sandwich structure with graded foam core has a better energy absorption capability compare to the one with uniform foam core.