Geometry does matter²

Nature is full of materials that exhibit astonishing properties that are not available in engineering materials. The study of the underlying structure of such materials has revealed that geometry plays an important role in achieving such properties. Unusual physical and mechanical properties such as structural coloring in butterfly wings and shock absorption in woodpecker skull are examples of how geometry could be used for functionalization of materials. At the same time, recent advancements in (additive) manufacturing techniques have enabled us to fabricate engineering materials whose ultrastructure is geometrically very complex. It is therefore now possible to design engineering materials with unusual properties. In this dissertation, two types of geometrical designs are used for development of mechanical metamaterials with unusual properties. That includes 1. Cellular structures working on the basis of mechanical instability, and 2. Origami-based designs. The dissertation has been organized in two parts each covering one of the above-mentioned design types..