On the bending behavior of hybrid fiber–metal laminates (HFMLs) based on aluminum and glass/Kevlar fibers reinforced epoxy

In this work, the mechanical behaviors under flexural loading of fiber–metal laminates (FMLs) comprised of an aluminum alloy reinforced with glass fibers (GFs) and Kevlar fibers (KFs) embedded in an epoxy composite are experimentally investigated. For this purpose, non-FMLs, FMLs, and hybrid FMLs (HFMLs) are tested and their results are compared in terms of the flexural strength and modulus, strain to failure, toughness, interlaminar shear strength (ILSS), and specific properties. Results show that the incorporation of GFs on the compression side and KFs on the tensile side improves the bending properties of the HFMLs compared to the KF-based FMLs, which enhances the laminates’ resistance to bending loads. The HFMLs exhibit improvements of 24%, and 5% in flexural strength and modulus, respectively, compared to the KF-based FMLs. Moreover, hybridization significantly improves strain to failure by up to 115% compared to the GF-based FMLs. Additionally, the ILSS analysis reveals improved values in FMLs compared to non-FML samples, when GF-based FMLs demonstrate higher ILSS than KF-based ones, which can be attributed to GFs’ stiffness and high-quality bonding with the aluminum sheets. HFMLs attain a 19% improvement in ILSS compared to the KF-based FMLs. The failure mechanism depends on the intrinsic features of the studied fibers, while the studied FMLs display better damage tolerance. In this context, the HFMLs present enhanced toughness, delamination resistance, and the ability to prevent crack propagation, positioning them as promising candidates for lightweight structural applications where a balance between strength, stiffness, and toughness is required.