Project description

Motivation

The use of ultra-high-strength aluminium alloys will play an important role in future lightweight structures in the field of mobility. The special properties of this class of materials are required above all in electromobility, since the total weight of the vehicle and in particular its load-bearing structure play a decisive role due to limited energy storage capacities. However, the processes used to manufacture the products are not yet fully mastered.

State Hessen plays a decisive role here, as three automobile manufacturers, more than 10 bicycle manufacturers and numerous suppliers, such as manufacturers of forming tools and equipment, build components for electric mobility vehicles in Hessen.

ALLEGRO’s central theme fits very well into the research strategy of the University of Kassel, the “increase of ecological sustainability” and the goals of the TU Darmstadt, “from material to product innovation”. In addition to “sustainability”, ALLEGRO also takes up the focus on “materials and production technology” anchored in the mission statement of the University of Kassel. With the completed SFB TRR 30 “Process-integrated production of graded structures on the basis of thermo-mechanically coupled phenomena” a joint project could be worked on in the past years, which has provided impulses for ALLEGRO.

Within the framework of current projects, ALLEGRO forms a complementary pillar to LOEWE's focus on “Safer Materials” in this central research area. Through the profile area "From material to product innovation", successful research on novel materials and their transfer into technical applications is also firmly anchored in the research profile of the TU Darmstadt. Evaluation with regard to criticality, efficiency and synthesis as well as design with regard to substitution, recycling and raw materials link the three pillars “materials, processes and product innovation”. ALLEGRO fits seamlessly into this research focus of the TU Darmstadt and thus strengthens the sustainability concept of all applicant research institutes.

ALLEGRO also fits into the research strategy and the complementary projects of the Fraunhofer LBF, which provides for the integration of production process-induced local material properties into the operational design and evaluation of cyclically stressed components and structures (process-related operational stability). Based on the characterization of the cyclic material behaviour under consideration of the manufacturing and joining processes, material models are developed for the CAx application in order to further develop the numerical lifetime estimation for components by exploiting the lightweight construction potential of modern materials, material systems and manufacturing processes. ALLEGRO explicitly pursues the declared goal of both universities and the Fraunhofer-Gesellschaft of increasing the number of young female scientists, especially in the MINT subjects in which they are underrepresented.


Aims and Visions

In ALLEGRO, plastic deformation at high temperatures is achieved by deep drawing (with stretch drawing components) and roll forming. The necessary tools are designed and integrated in fully instrumented test facilities. Strategies are implemented to achieve the highest possible spatial resolution of properties. Suitable heating methods must be identified and integrated for both forming processes. By varying the forming parameters, the field of process-property correlations is developed. The tribological system of tools and hot semi-finished aluminium products must be characterized and designed. Suitable coating systems must be developed, characterized and applied to the tools. 

The joinability of the formed semi-finished products is examined. FSW, LBW and MPW are suitable processes with little or no component influence. The challenge in joining is to maintain grading or even grading by the joining itself. The material properties, the microstructure and the component behaviour are evaluated by determining the static and cyclic material behaviour as a function of the degree of forming, the heat treatment and the joint. A trilinear approach for improved recording of the cyclic material behaviour and the implementation of the transient gradient material behaviour in a numerical stressability analysis deepen the understanding of the process.

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