Process simulation of thermoforming of thermoplastic sandwich materials made of Honeycomb and Cross-Ply

The demand for light-weight composites is increasing phenomenally especially in aviation, automotive and ship building sectors. As everyone addressed carbon footprints and global warming made by high fuel and energy consumptions and shifting towards specific tailor-made functionally performing materials. This need for light-weight materials is satisfied by honeycomb sandwich laminates as they have proven their advantages over conventional materials with specific weight to strength ratios. With advantage of thermoplastics in high volume production and processability, the sandwich laminates meet the industrial usage. In addition to that the flat semi-finished sandwich laminates are further processable to complex structures to meet different part geometries, with a novel thermoforming procedure by which the sandwich laminate is heated to a thermoforming temperature such that matrix material of face sheet lies above melting temperature and core material lies below melting temperature, then pressed to form into desired geometry. Currently, these materials are investigated for reproducibility in large mass scale owing to the current automation and digitalizing platforms with controlled heating and forming.

Using FEM tools, the manufacturing processes can be optimized by changing the process parameters and material configuration. For this a finite element model is developed considering material, geometry and boundary non-linearities, focused on complex honeycomb geometry and fiber-oriented UD-tapes at meso-scale level. Such developed model is tested for different material combinations, geometries and forming conditions. By this approach the probability of manufacturability of a component through specific technique can be investigated, which saves the material and time in the process of developing a new component. The difficulties in developing such complex model are many like core-face sheet interaction, honeycomb cell walls deformation behavior in melt zones and pre-deformed cell walls during lamination. All these cases will be investigated in this current project.