Natural Armor: Interdisciplinary Convergence Among Engineering, Architecture and Evolutionary Biology

Biological exoskeletons or "natural armor" systems are multilayered, hierarchical structures that serve many functions, in particular protective mechanical roles such as; penetration, wear, and scratch resistance, minimization of back deflection and potential blunt trauma, damage detection and sensing, self-repair and regeneration, and, in certain cases, flexibility and mobility. We can learn much from biological organisms that have evolved over millions of years a veritable encyclopedia of environmentally-friendly engineering designs for protection against specific predatory and environmental threats. Natural armor functions efficiently by elegantly balancing protection, tissue damage tolerance, weight, and mobility requirements to maximize survivability. In order to elucidate the design principles of these fascinating materials, nanomechanics methodologies have been employed including; the measurement and prediction of extremely small forces and displacements, the quantification of nanoscale spatially-varying mechanical properties, the identification of local constitutive laws, the formulation of molecular-level structure-property relationships, and the investigation of new mechanical phenomena existing at small length scales. Additionally, the quantification and understanding of how animal exoskeletons utilize morphometry or shape to achieve maximum survivability from predatory and environmental threats will be discussed. Exoskeletons are imaged in three-dimensions using X-ray microcomputed tomography and then these data are used to fabricate, experimentally test and simulate the mechanical behavior of macroscopic 3D printed bio-inspired prototypes of exoskeletal assemblies in order to elucidate morphometric design principles, the interplay between morphometry and materiality, and to create new bio-inspired hybrid flexible protective designs. This talk will focus on a number of classes of natural armor: flexible, transparent, those that exhibit resistance to biochemical toxins, kinetic attacks, extreme thermal fluctuations, and blast. Model systems to be discussed include "living fossils" such as armored fish, deep sea hydrothermal vent species, echinoderms and molluscs with articulating segmented armor (e.g. chitons, urchins), and the transparent exoskeletons of certain crustaceans.