In situ Hybridization during deep drawing: Thermoplastic Fiber-Metal-Laminate (FML) parts based on reactively processed polyamide 6

Structures based on Fiber-Metal-Laminates (FML) are powerful hybrid material concepts, which are rudimentally used for structural parts in air- and spacecrafts. A more widespread use of these materials has failed so far, due to a lack of proper production technologies in order to manufacture FML in a mass scale process with net shape geometry that exceeds slightly curved two-dimensional parts, with repeatable quality. So far production processes using multiple steps are required in order to manufacture complex shaped FML. Alternatively, conventional forming of the FML is employed and local wrinkling and breaking of fibers in highly deformed regions are tolerated.Therefore the objective of this project is the manufacturing of structural FML-parts based on aluminum or steel sheets in a direct combined deep drawing and infiltration net-shape process allowing hybridization which is based on the reactive processing of thermoplastic prepolymers (T-RTM). The low viscosity of the reactive mixture enables rearrangements of fibers during deformation of the FML. Therefore large deformations of the FML can be carried out intrinsically within the solidification window without damage to the composite constituent. In addition to the production-related research, process- and structural simulation are employed as well as research in the field of material science and engineering in order to increase the understanding of the correlation between production process, structural behavior and materials properties of thermoplastic FML. Concerning production technology the question of how and at what time the injection process is best incorporated into the forming of multi-layered FML is raised. Furthermore, the relation between process, structure and properties of thermoplastic FML needs to be derived taking the accumulation of damage into account. Due to the fact that the composite constituent lies within the FML it cannot easily be investigated after forming and being surrounded by sheets of metal the use of CT scans is also problematic. Therefore, adapted methods to analyze and simulate the change in microstructure have to be developed. In addition, different treatments of the metallic surface are investigated with the objective of gaining the best interface performance in conjunction with the polymerization of the matrix. Concerning the structural behavior of thermoplastic FML it is also important to analyze how the viscoelastic-viscoplastic properties of the metal/matrix-interface influence the thermal and mechanical behavior of the hybrid structure and how these properties are best implemented in simulation.