Targeted adjustment of graded properties using in-situ hybridization for the production of property-optimized, thermoplastic-based fiber-metal laminates

The aim of the initial application was the development of a one-step process for the production of three-dimensionally formed fiber-metal laminates (FML), which could be fulfilled by basic tests and the production of demonstrator components. Thereby the production time and costs can be reduced and the formability of FML can be increased. The two industrial processes deep drawing and resin transfer molding (RTM) were combined. A reactive thermoplastic matrix was injected during the forming process, which polymerizes after forming and forms the interface to the metallic cover sheets. This allows the semi-finished product form and material to be freely selected and combined. However, the components are not designed to withstand the loads, so that the weight saving potential is not optimally exploited. In the second phase, the aim is to exploit the potential of these combination possibilities in such a targeted way that the process is enabled to produce load-adapted components. In this way, load-adapted components can be produced by positioning material at the required point and in the desired orientation, as is also known in sheet metal forming under the term "tailored blanks". The resulting hybrid architecture can no longer be considered homogeneous with regard to infiltration. For this purpose the exact knowledge of the flow behavior of the matrix during the forming process is crucial. In the initial application this could only be investigated indirectly by experimental die filling studies. The focus of the second phase will therefore be the experimental and numerical description of the flow behavior also for the infiltration of load-adapted components. For this purpose, it is now of high importance to integrate the mould filling simulation into the process simulation, since the areas with different numbers of layers have different infiltration properties. In order to be able to represent this numerically, detailed information about the permeability of the used fiber textiles as a function of the fiber volume content is required, which is the result of draping and compacting. Accordingly, the mould filling simulation has to be combined with the simultaneously running draping/forming simulation. In this way, not only for a homogeneous interlayer, but also for inhomogeneous interlayers, the mould filling during the process and its influence on the forming behaviour can be tracked, which leads to a considerable added value for the process understanding of this method.