Disorder Enhances the Fracture Toughness of Two-Dimensional Mechanical Metamaterials
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Subject
disordered materials
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Funder
US Department of Defense NDSEG
Villum Foundations Experiment Programme
Grant number
DMR-2309043
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Abstract
Mechanical metamaterials with engineered failure properties typically rely on periodic unit cell geometries or bespoke microstructures to achieve their unique properties. We demonstrate that intelligent use of disorder in metamaterials leads to distributed damage during failure, resulting in enhanced fracture toughness with minimal losses of strength. Toughness depends on the level of disorder, not a specific geometry, and the confined lattices studied exhibit a maximum toughness enhancement at an optimal level of disorder. A mechanics model that relates disorder to toughness without knowledge of the crack path is presented. The model is verified through finite element simulations and experiments utilizing photoelasticity to visualize damage during failure. At the optimal level of disorder, the toughness is more than 2.6 times of an ordered lattice of equivalent density.