The Influence of Material Configuration of Fibre-Metal Laminates with Alumina Core on Flexural Strength

Fibre metal laminates (FMLs) consisting of layers made of PA6 polyamide prepregs reinforced with glass and carbon fibres and an aluminium alloy core are the new variant of the other types used by aerospace FML materials such as GLARE or CARALL. By using a thermoplastic matrix, they can be shaped by stamping processes, which allows for a more efficient production process than classical laminating methods such as vacuum bagging. In addition to the improved impact energy absorption efficiency, the metallic core can be utilised to effectively bond the composite part to adjacent metallic structures. This article presents the influence of the material configuration of fibre-metal laminates consisting of continuous fibre-reinforced thermoplastic outer layers integrated with a layer of metallic aluminium alloy inserts—a number of layers, type and direction of reinforcing fibres—on the static and fatigue flexural properties. In this study, eight laminate configurations were prepared using a one-step variothermal consolidation process. The results showed that in the three-point flexural fatigue test, the samples exceeded 10⁶ cycles at stresses <30% of the static bending strength. Laminates with predominantly longitudinally reinforced layers showed the highest fatigue strength among the FML samples analysed. The type of reinforcing fibres and the number of layers were less affected on the analysed mechanical properties.