Novel additively manufactured dihedral tiling architected metamaterial conformed with pentagon and rhombus: design and mechanical properties

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The design of novel mechanical metamaterials has drawn inspiration from several sources to develop new structures. Additionally, additive manufacturing has widened the possibilities for producing intricate geometries. With this in mind, a novel architected metamaterial based on dihedral tiling is presented here, and its mechanical response is characterized experimentally. The architecture comprises two shapes: a pentagon and rhombuses, arranged in a manner dependent on each other. Three parameters were defined as variables to generate several design variations and analyze the impact of geometry on their effective mechanical properties: pentagon edge length (l), pattern rotation angle (θ), and strut thickness (t). For this purpose, the selected designs were additively manufactured using Thermoplastic Polyurethane (TPU) and tested under compression. It was found that t is directly proportional to relative density, and consequently, to apparent stiffness, while l is inversely proportional to both properties. On the other hand, θ has a minor influence on apparent stiffness and is more related to the deformed shape obtained. Overall, it was observed that the response depends on the combination of all geometrical parameters, meaning the apparent properties cannot be related to the response of only one of the shapes. This behavior differs from lattices based on a singular shape, in which the properties of the whole metamaterial are usually related to those of the unit cell.