In-plane flexural behaviour of a hybrid titanium lattice/FRP short beam

A solution to meet higher performances in terms of mechanical properties and lightweight is the adoption of innovative hybrid structures made of metallic lattice core and composite material skins, because both of them are characterised by high specific strength and stiffness. Flexural load is a stress configuration commonly present in structural frame parts of vehicles; however, the out-of-plane load arrangement has often been considered, while in-plane one has been never analysed. Therefore, in this work, attention was paid to this latter configuration, and a short beam specimen was considered. A comparison between the mechanical answer of two types of skin materials, CFRP (Carbon Fiber Reinforced Polymer) and AFRP (Aramid Fiber Reinforced Polymer), was carried out. For both CFRP and AFRP a similar maximum load was recorded, even if that one of the latter was slightly higher, as well as the maximum displacement at break was the same for both types of specimens. As concerns the shape of the load-displacement curves, a sudden load drop after the attainment of the maximum load was observed. The increasing load section of the curves was characterised by an initial linear part (even if a slight deviation from linearity was noted) followed by a first minor load drop, probably due to the fibres' breakage. The subsequent part showed a non-linear load increase with other load drops: also in this case, this trend was caused by fibres' breakage.