Light-weight construction: Robust simulation of complex loaded cellular structures

In order to reduce the energy consumption of moving parts as well as the total amount of the material used, diverse light-weight strategies are currently in the focus of industry and research. One promising approach is the application of additively manufactured cellular structures, which due to their low relative density are characterized by high relative strength. In contrast to other low-density materials, such as the well-known aluminum foams, the design of the cellular structures can be adapted to the outer load by local modification of the strut diameter or strut orientation. Consequently, a more efficient design can be achieved allowing for reducing the structural weight as well as the overall material use. Further advantages are seen in the relatively low building time (in comparison to bulk material) due to the low cross sectional area exposed by the laser, and in the applicability of cellular structures for improving the cooling capability of thermally loaded parts by designing the hollow spaces as channels for cooling media. For characterizing the fundamental behavior of cellular structures a first project was drafted with a focus on the occurring deformation mechanisms of metallic specimens under uniaxial and bending load. The results proved a good specific loading capacity but also a high influence of the cellular design on the resulting failure mechanisms. Likewise, the actual microstructural condition of the material turned out to be highly influential on the mechanical performance. A very high brittleness resulted in a different deformation pattern than a high ductility. A straightforward simulation of a simple cell geometry under uniaxial load showed a good accordance between the observed and simulated local deformations, but a simulation under bending load still proves difficult and the microstructural condition could not yet be taken into account. For industrial application a robust and reliable simulation is imperative, as the structural performance in dependence of both the cellular design and the microstructure have to be predictable under complex loading scenarios prevailing in many actual applications. Thus, the establishment of a robust FEA model for complex loaded cellular light-weight structures will be the aim of the present project. Based on the findings of a preliminary linearelastic simulation the examinations will be extended to linear-plastic deformation behavior including diverse material conditions by applying Ti-6Al-4V alloy (brittle) and 316L stainless steel (ductile). Furthermore, plastic cellular structures will be manufactured by Laser Sintering (LS) in order to verify the developed FEA model for a fundamentally different kind of material.