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The optimization of materials has accompanied us since time immemorial. Even today, mostly manageable variations in the chemical composition or in the process parameters are used to improve established materials step by step. However, it is increasingly the reverse route, top-down, based on a desired functionality or a specific application as a starting point. The material or the workpiece is then generated from scratch on a computer-based basis using complex numerical processes. The “Materials of Design” developed in this way also include the Architectured Materials, which are currently still essentially in the basic research stage.

An exact definition of this new class of materials also has yet to be established. In any case, it is about the inclusion of architectural features in the material development. So the arrangement of units in three-dimensional space - in addition to z. B. chemical composition and grain size - can be made an independent adjusting screw in the development of new materials. The aim is to expand the limits of the currently available combinations of material properties. Architectured Materials specifically combine different materials or material and free space. The result is composites and lattices with a highly complex hierarchical structure that extends over many orders of magnitude and is increasingly referred to as the architecture of the material.

Multifunktionalität ist integraler Bestandteil des Konzepts der Architectured Materials, ein Großteil der Forschungsarbeiten zielt auf die Erweiterung eines Werkstoffs um eine gewünschte Funktionalität ab. Beispiele hierfür sind selbstheilende Fähigkeiten, elektromagnetische Absorption, optimaler Wärmeaustausch, Selbstüberwachung, optische Eigenschaften oder ein negativer thermischer Ausdehnungskoeffizient. Darüber hinaus werden Architectured Materials entwickelt, die über ausgezeichnete mechanische Eigenschaften verfügen, insbesondere eine hohe Schadenstoleranz. Mit diesem Ansatz könnte ein sehr leichtes Material entwickelt werden, das aber gleichzeitig über ein hohes Energieabsorptionsvermögen zur Dämpfung von Druckwellen verfügt, wie sie z. B. bei Explosionen auftreten. In der Luftfahrt könnten Entwicklungen dieser Art zum wirkungsvollen Schutz von Strukturen vor Schall oder Vibrationen eingesetzt werden, auch der Erdbebenschutz soll Anwendungsgebiet solcher Architectured Materials werden. Einen weiteren Aspekt im Bereich der Luftfahrt und auch der Automobilindustrie stellt das Crash-Verhalten unter Berücksichtigung des Leichtbaus dar. Im Bereich der Energieerzeugung könnten Architectured Materials darüber hinaus auch als Trägermaterial für Solarzellen und elektrochemische Generatoren eingesetzt werden. Grundsätzlich ist die Entwicklung von Architectured Materials interessant für Anwendungsbereiche, bei denen konträre Anforderungen von einem einzigen Material erfüllt werden sollen.

Such a multifunctionalization of a material should succeed through the incorporation of design elements such as a wide variety of cellular, fiber, layer, tubular or spiral structural elements, but also recurring structural overlays, interlocking seam structures or gradients in the form of a continuous spatial course. The decisive factor is the combination of different structural levels, mostly from macroscopic structuring down to nanostructuring (multiscale). So a property of the material can be structured on z. B. microscopic level can be achieved, while another property is realized through the combination of several design elements on the nanoscopic level.

The use of the term Architectured Material is still at an early stage and can be observed primarily in two large and dynamic research directions, the periodic lattice structures and the biocomposites. The most prominent examples include replicas that are based on natural, extremely resistant materials such as mother-of-pearl or bone. In contrast to lattice structures, they have very different design elements, which significantly increases the simulation effort. This complexity over several orders of magnitude requires very specific manufacturing methods. Especially with structural details in the sub-μm range, the required precision of the structural units on the one hand and the size of the overall object on the other hand represent a hurdle. The unique design freedom of additive manufacturing processes as well as their rapid development and distribution predestines them for the production of such materials. However, the simultaneous processing of different materials is still at the beginning of the development. With this complexity, the characterization of the architecture and especially the checking of integrated functionalities is a challenge.

The Architectured Materials is based on an overall concept that includes the core competencies of design of structural features, manufacturing technology and characterization. High development costs must therefore be assumed for the implementation of such structures. At the moment there are only a few approaches on the way to commercialization, above all complex lattice structures that could be commercially available in the medium term. The development of practically usable, multifunctional multicomponent materials, as they are contemplated in very few research projects, is to be assessed much more long-term, since a stronger bundling of research efforts in the three required core competencies (i.e. design, manufacturing technology, characterization) would have to succeed.

Dr. Heike Brandt