Recent approaches of interface strengthening in fibre metal laminates: Processes, measurements, properties and numerical analysis

Recently, there is a pressing need for high-performance and lightweight structural materials in aircraft and automobile industry; fibre metal laminates (FMLs) are suggested ideal candidates for aviation industry. FMLs are hybrid composite material comprised of thin-metal sheets and fibre-reinforced polymers (FRPs). By combining the features of both components, FMLs possess high tolerance to fatigue damage, exceptional impact resistance and an outstanding weight-to-strength ratio. However, maintaining high structure integrity of FML layers – without debonding – remains the primary challenge in FMLs-based structures. The present review explores the recent developments in manufacturing techniques and surface treatments aimed at enhancing the interfacial strength between FML layers. Recently, adding nanofillers into FRPs and FMLs is gaining attention. These nanofillers can enhance mechanical performance of FRPs/FMLs, strengthen the interface in FMLs; and add functionalities such as gas and water impermeability. The article discusses the recent studies on employing nanofillers in FMLs and adhesively bonded structures; and their (nanofillers) role in enhancing the crack resistance of FMLs. It also explores failure mechanisms in FMLs through experimental methods and advanced numerical simulations. A comprehensive review of the existing studies assists in understanding the complex failure mechanisms, aiming to find optimal input conditions that yield desired mechanical performance. Furthermore, the article introduces machine learning techniques in adhesively bonded structures and potential application in FMLs-related research. The article concludes with perspectives on the limitations, current challenges, and future prospects for FMLs and nanofiller-reinforced FMLs.