| Abstract | Natural suture structures, characterized by hard segments joined along a patterned weak interface, are found to provide unique toughening mechanisms for brittle bulk biological materials. Hierarchical ceramic sutures inspired by white-tailed deer crania and diabolical ironclad beetle exoskeletons are developed using a biomimetic approach. Overlapping geometries unlock twin energy absorption mechanisms. Ceramics with Surlyn-infiltrated precision laser-cuts are fabricated using a semi-automated and smart advanced manufacturing platform. A parametric study comprising four-point bending, fracture toughness, and tensile tests is conducted to evaluate toughness, strength, and stiffness with geometrical interlocking in two hierarchical orders. Digital image correlation is utilized to analyze the local toughening mechanisms and failure modes in the fracture tests. For all three metrics, the panels with second-order hierarchy outperform the anti-trapezoidal equivalents. The ceramic sutures show up to 590%, 340%, and 700% improvements in energy absorption in the tensile, bending, and fracture tests, respectively, owing to the optimal first- and second-order interlocking angles. The high-order fractal interlocking at multiple scales and overlapping teeth are found to provide high flexibility and failure resistance, whereas progressive fracture mechanisms delay catastrophic failure by up to 50%. The concept of hierarchical suture can lead to industrially applied ceramic systems with tailored mechanical performances. |
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