| Summary: | Fracture toughness, rather than strength, is often the limiting factor of structural materials. Developing new base materials with improved fracture toughness often takes more than a decade. Alternatively, topological design has recently been expanded by additive manufacturing. In the present study, architected planes of internal porosity mimicking a weak interface were found capable of arresting and deflecting a propagating crack, delaying fracture. This concept was demonstrated experimentally in solid beams of polymeric 3D printed material, and in gyroid metamaterials constructed from either a brittle polymer or stainless steel. Improvements in fracture toughness ranged from 22% to 300% depending on the material. Especially with topological optimization, toughening via designed porosity provides an avenue for cost-effective and simple toughening across a range of materials.
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