UC San Diego

Designs derived from nature have become a perfect blueprint for today's engineers and scientists to follow and implement. One particularly noted area is the defense industry, wherein flexible dermal armor inspired by nature has been pioneering many sophisticated technologies and designs in recent years. Designers today are considering borrowing aspects of flexibility and mobility of natural dermal armors to enhance the maneuverability of man-made armor by imitating the following mechanisms : (1) 3D interlocking; (2) interconnectivity; (3) hierarchical structure; (4) structural toughening mechanisms. The motive of this research is to examine the flexible dermal armors that Mother Nature has offered. The innate structure and mechanical properties of osteoderms in the following animals have been investigated: armadillo, alligator, and leatherback sea turtle. All these animals have one commonality: they have bony plates embedded in their soft shell that make their skin flexible and compliant while also offering protection. Each of these animals has its own unique way with associated functional mechanisms to achieve this. First, the armadillo uses a flexible biological material, collagen, to connect the bony plates and to provide flexibility. Second, the osteoderms of an alligator have bone-toughening mechanisms to reinforce themselves from a predator's attack. Third, the leatherback sea turtle exhibits a zigzag suture design that incorporates interlocking methods into its armor that enables it to dive deep into the ocean (depth of 1200 meters). Mechanical tests, characterization, and analysis were performed to identify the principal mechanisms that provide both toughness and flexibility in the three different dermal armors. The damage mechanisms are connected to the microstructural characteristics. The toughness and flexibility of the natural designs were found to be quite remarkable