Fracturing and Controlled Cracking Path in Topological Maxwell Lattice

We show fracturing analysis of topologically polarized Maxwell lattices upon external stretching. Topological mechanics led to the discovery of topologically protected floppy modes and states of self-stress at the edges and the domain walls of Maxwell lattice. To put Maxwell lattice into practical fabrication, we need realistic structural lattices characterized by non-ideal, finite-thickness hinges. Recent progress has shown that in both ideal and realistic lattices, when topological Maxwell lattices are being stretched, stress focuses on states of self-stress domain walls, and bond-breaking events start at these domain walls, even in the presence of cracks, implying the robustness of topological polarization in the Maxwell lattice. In this work, we stretch the lattices to the failure stress of the material and observe non-trivial cracking paths in the topological materials. We use simulations and theory to understand the cracking behaviors, and we further show how to use defects, material properties, and topological decay rate to control and program the failure patterns.