Extreme Mechanics of Metamaterials: From ideal to realistic conditions

Projektbeschreibung

Leistungsfähige Materialien für Luft- und Raumfahrt bis Prothetik

Mechanische Metamaterialien sind künstliche Strukturen, die gleichzeitig sehr leicht und sehr fest sein können. Gleichermaßen können sie ihre Form selbständig verändern, um die gewünschte Funktionalität zu realisieren. Die digitale Fertigungstechnik hat sich in den vergangenen Jahren derart weiterentwickelt, dass diese Materialien in das Reich der Mechanik vorgedrungen sind und die Zahl ihrer Funktionalitäten zugenommen hat. Das EU-finanzierte Projekt Extr3Me erforscht nun die Auswirkungen inhomogener Randbedingungen. Außerdem wird es die Empfindlichkeit gegenüber geometrischen Fehlstellen untersuchen und die Rolle der Dissipation berücksichtigen. Das Gesamtziel des Projekts besteht darin, die Grenzen der Festkörpermechanik zu erkunden und robuste, moderne Funktionalitäten zu entwickeln, die für ein breites Spektrum an Bereichen geeignet sind.

Ziel

Manipulating physical signals such as light, sound, heat or motion is a vital challenge in multiple areas of science. Due to recent advances in digital fabrication techniques, the last years have seen a revolution in artificial periodic composites with on-demand electromagnetic, acoustic, thermal and mechanical properties. These so-called metamaterials become particularly interesting in mechanics, where geometrical effects and nonlinearities are much stronger than in any other physical field. Over the past 5 years, the community -including myself- has discovered a plethora of “extreme” functionalities, e.g. mechanical metamaterials that are very light, stiff and strong at the same time, that have negative elastic moduli or that exhibit programmable shape-changes. Importantly, such advanced properties are typically designed through a purely geometrical framework. Yet, this impressive progress is so far confined to idealized settings, namely for homogeneous boundary conditions, imperfection-free structures and purely elastic constituents under quasi-static driving. This traditional focus severely limits our understanding of metamaterials and their potential for applications. Here, I propose to uncover the extreme mechanics of metamaterials under realistic conditions. Specifically, by generalizing the geometrical framework to allow for deviations from the ideal limit, and by validating it through a wide array of experimental and numerical techniques, I will establish: 1) the effect of inhomogeneous boundary conditions; 2) the sensitivity to geometric imperfections; 3) the role of dissipation. Just as the fundamental understanding of defects and dislocations revolutionized materials science, by exploring perturbations in metamaterials I will push the frontiers of solids mechanics and open up avenues for the design of robust advanced functionalities tailored to realistic complex scenarios, from prosthetics to aerospace.