Reverse engineering nature : design principles for flexible protection inspired by ancient fish armor of Polypteridae

Abstract

This thesis is about designing structures that combine the dual functions of mechanical protection and flexibility of motion. The structures are inspired by principles observed in the ganoid squamation (scale assembly) of an ancient fish species called Polypteridae, which first appeared 96 million years ago. Prior work on Polypteridae has focused on understanding the role of the inherent material properties (e.g., stiffness, strength, etc.) of the individual bony scales to provide penetration resistance. Here, geometric design is explored at increasingly larger length scales including 1) morphometric features within individual scales, 2) morphometry of the individual scales as a whole, 3) scale-to-scale interconnections and anisotropic ranges of motion, and, lastly, 4) the entire assembled scale squamation and anisotropic ranges of motion of the entire fish body. Experimental, computational, and mathematical methods employed were micro-computed tomography, microscopy, morphometric analysis, and three-dimensional printing of prototypes. The geometrical design principles discovered were related to biomechanical mobility and protection and then implemented into a generalized, functional design system which possesses similar anisotropic distinctive degrees of freedom and ranges of motion as Polypteridae. The design system offers potential for applications in fields of transportation, military, and architecture.