Development of programmable cellular metals by combined alloy and geometry optimization (ProZell)

• Applicants: Dr.-Ing. Thomas Hipke; Professor Dr.-Ing. Ulrich Krupp
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 437986279

Cellular metals describe a class of materials that is characterized by a wide portfolio of properties. Therefore, potential applications are manifold. However, industrial application is currently limited, which is due to an insufficient fundamental understanding of the correlation between production process, structure and properties. This lack in understanding leads to inhomogeneous and non-reproducible cell structures. In general, cellular materials exhibit open or closed cell types, resulting in low part density. Additionally, the structure and properties of the individual cells vary strongly and thus, a wide spectrum of properties including functional integration and/or programmable mechanical properties may be achieved. In this context, programmable structures consider tailoring of the local stiffness and strength by adaption of the cell geometry. The proposed project addresses the aforementioned shortcomings of cellular metals and sets the following focus:“Development of a load-optimized singular cell with a regular, open cell-type structure that has been adapted to a specific alloy. This cell is referred to as the ideal cell, which can be extended to a periodic cell structure and produced by industrially relevant processes”.The ideal cell will be designed based on maximum energy absorption capacity under consideration of the elastic and plastic anisotropic material behavior of high-manganese TRIP/TWIP steels. The outstanding mechanical properties of TRIP/TWIP steels will be combined with the geometrical design of cellular structures and allow for programming of these structures. The developed ideal cell structure will be transformed into an actual cell structure by consideration of the processing conditions of industrial production processes, i.e. casting and selective laser melting. On the one hand, casting allows for affordable production of parts with larger dimensions. However, the process-related boundary conditions (such as demoldability) limit the freedom of the geometrical design. On the other hand, selective laser melting enables production of geometrically very complex parts. Prototypes and specimens consisting of the actual cell structure will then be manufactured and comprehensively characterized with respect to their microstructure and mechanical properties including benchmarking. The results of simulations and characterization serve as a basis for determination of structure-properties-relationships. The findings will be used to develop advanced materials models that allow for arbitrary adjustment of the behavior of the actual cell structures (programming).

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr.-Ing. Christian Haase