Design of responsive materials using topologically interlocked elements

Abstract

In this work we present a novel approach to designing responsive structures by segmentation of monolithic plates into an assembly of topologically interlocked building blocks. The particular example considered is an assembly of interlocking osteomorphic blocks. The results of this study demonstrate that the constraining force, which is required to hold the blocks together, can be viewed as a design parameter that governs the bending stiffness and the load bearing capacity of the segmented structure. In the case where the constraining forces are provided laterally using an external frame, the maximum load the assembly can sustain and its stiffness increase linearly with the magnitude of the lateral load applied. Furthermore, we show that the segmented plate with integrated shape memory wires employed as tensioning cables can act as a smart structure that changes its flexural stiffness and load bearing capacity in response to external stimuli, such as heat generated by the switching on and off an electric current.

The mechanics of tessellations – bioinspired strategies for fracture resistance

“…materials have shown to be defect-tolerant, exhibit tunable bending stiffness and even allow for acoustic absorption. 28 A natural (but largely unexamined) example of such geometric interlocking structures is seen among the several genera of durophagous (hard-prey crushing) myliobatid stingrays. 27 The teeth of these fishes look nothing like the familiar pointed cusps of sharks, rather ranging in form from blunt-ended bars to extended hexagons to chevrons, nesting together with interlocking morphologies described anecdotally as ''overlapping shelve'' or ''tongue-groove'' mechanisms and with varying degrees of tightness of fit 29 (Fig.…”

Short review on architectured materials with topological interlocking mechanisms

“…Schematics and examples of topological interlocking material (TIM). A, Individual tetrahedral building block whose mid plane section (ABCD) is square; B‐D, Individual building block (grey) geometrically constrained by four neighboring identical building blocks (blue); D, Plate‐like interlocked structure with periodic arrangement of tetrahedral building blocks; E, TIM with truncated tetrahedral building blocks; F, TIM with osteomorphic building blocks…”

“…This results in a pseudo‐ductile behavior without the catastrophic failure exhibited by plain glass (Figure C). Additionally, it has been shown that the overall structural integrity of TIM is not largely affected by failure or damage of a few blocks . The dependence of various mechanical properties on the interlocking angle θ , ie, the tilt angle of the interfaces versus a vertical plane, has been investigated for TIM with truncated tetrahedral blocks, and is summarized in Table .…”

“…Additionally, it has been shown that the overall structural integrity of TIM is not largely affected by failure or damage of a few blocks. 2,19 The dependence of various mechanical properties on the interlocking angle θ, ie, the tilt angle of the interfaces versus a vertical plane, has been investigated for TIM with truncated tetrahedral blocks, 22 and is summarized in Table 1. It shows that stiffness increases with increasing interlocking angle.…”

“…Architectured materials have attracted much attention in recent years. Their general concept is to design unit cells with special microstructures in order to obtain the desired material responses in terms of mechanical, acoustic, optical, and thermal properties on the macroscopic level. Generally, architectured materials can be divided into two types based on the filling patterns of unit cells: cellular materials with slender structures and dense materials made from solid building blocks.…”