Toughening by interpenetrating lattices

As structural lattice metamaterials become more accessible through 3D printing, there is a need to better understand their fracture behavior, which sets practical limits for engineered structures. Lat-tices face a problem of decreasing toughness as their density and cell size decrease. Recently discovered interpenetrating lattices, made by weaving two or more physically separate lattices through the same volume, offer a potential path to significantly improve fracture toughness by increasing the fracture process zone size and inducing unique contact and friction toughening mechanisms. Interpenetrating lattices possess a steeply rising resistance-curve behavior, with the final toughness associated with catastrophic frac-ture an order of magnitude greater than the initiation toughness needed to begin advancing a crack. Remarkably, the interpenetrat-ing lattice's toughness in certain topologies can be five times greater than its corresponding, fully dense solid base material, and the toughening effect can be tailored by controlling the mechanical mismatch of the constituent sub-lattices.

Automated summary

As 3D printing technology advances, the accessibility of structural lattice metamaterials increases, requiring a better understanding of their fracture behavior. Interpenetrating lattices, created by weaving physically separate lattices together, offer a promising way to enhance fracture toughness by increasing the fracture process zone size and introducing unique toughening mechanisms. These lattices display a rising resistance-curve behavior, with significantly higher toughness than the initiation toughness needed to start a crack. In certain topologies, the toughness of interpenetrating lattices can be five times greater than that of their corresponding solid base material, and the toughening effect can be customized by controlling the mechanical mismatch of the constituent sub-lattices.