Synergistic strengthening in interlocking metasurfaces

Abstract

Interlocking metasurfaces (ILMs) are a new class of structural metamaterials consisting of autogenous latching features. ILMs offer non-permanent joints that are an alternative to fasteners, welds, or adhesives. The mechanical properties of ILMs, including strength and stiffness, are governed by both the shape of the individual latching unit cells and the interaction between unit cells. These cross-cell interactions provide a synergistic effect that distinguish ILMs from ordinary isolated latching features: specifically, as the number of interacting unit cells increase, the strength of the ILM also increases. Remarkably, in the present study, ILMs demonstrated interfacial tensile strengths that were as much as four times stronger, and stiffer, than the equivalent isolated latching components. Computational analysis and experimental measurements confirmed the cross-cell interactions associated with ILMs. Both finite element analysis and digital image correlation strain field mapping reveal that unit cells near the edge of the ILM have different load-limiting deformation and failure mechanisms than those away from the edge: unconstrained edge unit cells bend out of the way, thus allowing the interlocking features to move past one another whereas interior unit cells do not. Due to their synergistic strengthening, ILMs show promise as a novel joining technology.