Scutoids as Building Blocks for Topologically Interlocking Material Systems

Topologically interlocking material (TIM) systems are constrained assemblies of building blocks with geometry such that individual unit elements cannot be removed from the assembly without complete disassembly. These assemblies can bear load in the absence of adhesive bonds. TIM systems with scutoid-shaped building blocks are investigated. Scutoids are prism-like shapes with two polygonal faces and contain vertices on the lateral sides which enable geometric interlocking. The quasi-static mechanical behavior of two types of scutoid-based TIM systems is investigated and compared to reference tetrahedron-based TIM systems. TIM systems are realized as plate-type assemblies and a central point-force load is considered. The computational analysis is conducted with the finite-element method. Scutoid-based TIM systems are found, in aggregate, to match or exceed the performance of the tetrahedra-based systems. It is documented that TIM systems in general, but scutoid-based systems in particular, emerge to possess chiral characteristics. The combination of building block symmetry and assembly symmetry together determines the type of chirality in the mechanical response. Experimental data validates the computational finding. In summary, considering scutoids as building blocks for load-carrying TIM assemblies opens the pathway to new classes of mechanical behavior in systems where structure and microstructure strongly interact with each other. Scutoid building blocks provide alternatives to polyhedra and osteomorphic bricks when constructing topologically interlocked material systems. Assemblies of pentagon and hexagon scutoid building blocks are found to possess higher stiffness and strength than assemblies of tetrahedra, over a large range of inter-block friction conditions. Scutoid assemblies exhibit a rich mechanical response characteristic which can include transverse and in-plane chirality. image (c) 2024 WILEY-VCH GmbH