THE IMPACT REGION OF THE MANTIS SHRIMP: A MULTIREGIONAL PARTICLE AND SINUSOIDALLY-ARCHITECTED HELICOIDAL BIOCOMPOSITE

摘要

We report on the structure of the outer region (termed "impact region") of the stomatopod raptorial appendages (dactyl clubs). Within this impact region we uncover a novel and previously unobserved architectural design, which we call "herringbone structure" that consists of a compacted and pitch-graded sinusoidal arrangement of helicoidally arranged alpha-chitin/hydroxyapatite fibers and exhibits a notable departure from the traditional helicoidal (Bouligand) structure found within most crustacean exoskeletons. We find this structure, which in combination with an outer dense particulate apatite layer enhances stress redistribution under compressive loading and yields a tough and impact-resistant structure capable of delivering high-energy strikes without failure. We also reveal previously unreported structural and mechanical details from this region that not only provide new insights to the design of impact resistant and damage-tolerant composite materials.