Hybrid materials like fiber-metal laminates (FML) combine the advantages of two material classes resulting in high mechanical performance while maintaining the possibility of lightweighting structures. Due to their diverse application potential and growing demand, a comprehensive ecological lifecycle management of this hybrid material is required. A possible recycling strategy has proven to be the incorporation of an additional thermoplastic interlayer. By chemically or thermally deactivating this additional layer at the end of the components life cycle, the fiber-reinforced material can be separated from the metal, thereby enabling the reuse of the individual components.
The study presented aims to investigate and optimize the manufacturing process of carbon fiber reinforced (CFRP) epoxy-based – aluminum laminates featuring such a thermoplastic interlayer. Hereby, the hybridization is conducted via hot-pressing. Two manufacturing routes are considered. Firstly, an in-situ manufacturing is carried out, combining the three different (CFRP, thermoplastic foil, aluminum) materials via hot-pressing. Secondly, an ex-situ approach aims to consolidate the epoxy-based prepreg material in a first step and combine it with aluminum and thermoplastic foil subsequently. Through this two-stage fabrication process (ex-situ), the possibility of reusing the CFRP to manufacture a FML can be tested. The impact of varying layer thickness of the aluminum and the laminate design, respectively number of aluminum layers or lay-up of the epoxy-based carbon fiber reinforced prepreg, is analyzed in detail. Possibilities for simplifying the fabrication process, such as mold-free hot-pressing, are also considered. The effects of the adapted fabrication process on the quality of the interfaces are analyzed using imaging techniques as the interlaminar bond strength between the individual layers of the laminate is critical for the mechanical performance of the FML. The results show that both presented manufacturing routes, in-/and ex-situ, are feasible and lead to fiber-metal laminates with a high bond strength.
This paper is based on investigations within the project TR 1815/3-1, which is kindly supported by the German Research Foundation (DFG).