The influence of composite core thickness on the perforation resistance of titanium-based FMLs

Fibre metal laminates (FMLs) have been widely used as structural materials in aerospace applications due to their superior properties compared to traditional fibre reinforced composites. FMLs are hybrid materials consisting of alternating sheets of metal and plain composite. The aim of this study is to investigate the impact response of FMLs that have potential applications in the next generation of aircraft. Here, the influence of the thickness of the composite core in a 2/1 (metal/composite/metal) titanium alloy-based fiber metal laminate were investigated under low velocity impact conditions. It is shown that increasing the thickness of the composite core resulting in higher values of impact force and absorbed energy. The FMLs offered a much higher specific perforation energy than that offered by the plain composite for a given thickness of composite core. Explicit finite element (FE) models were developed to predict the response of the laminates under low velocity impact loading, which were then validated by comparing the numerical predictions with the corresponding experimental results. The resulting FE predictions showed good agreement with the experimental data in terms of the load-displacement trace, peak impact force, absorbed energy and perforation mechanisms.