Abstract
Many biological systems have developed dermal armors to protect themselves against claws and teeth of predators. These protective coverings are mostly composites of minerals and organics arranged in complex hierarchical structures. In this study, we investigated and compared the structural and mechanical properties of various dermal armors, focusing on alligator osteoderms. Alligator possesses a bulletproof dorsal armor composed of bony plates called osteoderms, connected by non-mineralized collagen fibers to provide flexibility. Intricate porous system within the osteoderm was observed through synchrotron x-ray μ-CT scans, whereas the unique interwoven microstructure of the mineralized collagen fibrils was revealed by FE-SEM. Nano-indentation, compression and impact tests were performed to obtain multi-scale mechanical properties of osteoderms under both dry and hydrated conditions. Results were compared with other natural dermal armors, such as fish scales and turtle shells, and bio-inspired composite designs were proposed.