The Woodpecker\u27s Beak: An Optimally Designed Structure/Material for Energy Absorption and Shock Mitigation

Woodpecker beaks have the ability to absorb shock energy without any damage to their body. In his book Origin of the Species Charles Darwin mentioned that the “woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees” in trying to explain how adaptation led to evolutionary changes in the woodpecker. Did the woodpecker with its beak, tongue, tail, and feet really adapt over long periods of evolutionary time or was it designed by its Creator to live in its particular environment and conditions. The analysis in this study shows the intense complexity of the woodpecker’s beak arguing for an engineering design by its Creator. In particular, this study focuses on the structure-property relationships of the woodpecker beak at multiple length scales. In particular, the woodpeckers’ beaks were examined through microscopy and nano/micro indentation to quantify the structure-property relationships with the perspective of mitigating shock waves. The beak of a woodpecker comprises three layers; exterior keratin layer (rhamphotheca) composed of overlapping scales, middle foam layer, and inner bony layer composed of mineral and collagen fiber. Indentation testing revealed that the hardness value of the inner layer is two to three times higher than that of the exterior layer. The overall design of the beak, tongue, and hyoid bone with their specific structure-property relationships in addition to the subsystem designed for shock mitigation appears to have been specifically designed for absorbing energy as they effectively dissipate energy as a whole. The perfection of the beak’s architectural complexity and fine systemization are highly indicative of it being designed by its Creator

The effect of vanadium-carbon monolayer on the adsorption of tungsten and carbon atoms on tungsten-carbide (0001) surface

We report a first-principles calculations to study the effect of a vanadium-carbon (VC) monolayer on the adsorption process of tungsten (W) and carbon (C) atoms onto tungsten-carbide (WC) (0001) surface. The essential configuration for the study is a supercell of hexagonal WC with a (0001) surface. When adding the VC monolayer, we employed the lowest energy configuration by examining various configurations. The total energy of the system is computed as a function of the W or C adatoms’ height from the surface. The adsorption of a W and C adatom on a clean WC (0001) surface is compared with that of a W and C adatom on a WC (0001) surface with VC monolayer. The calculations show that the adsorption energy increased for both W and C adatoms in presence of the VC monolayer. Our results provide a fundamental understanding that can explain the experimentally observed phenomena of inhibited grain growth during sintering of WC or WC-Co powders in presence of VC

Atomistic Studies of Defect Nucleation during Nanoindentation of Au (001)

Atomistic studies are carried out to investigate the formation and evolution of defects during nanoindentation of a gold crystal. The results in this theoretical study complement the experimental investigations [J. D. Kiely and J. E. Houston, Phys. Rev. B, v57, 12588 (1998)] extremely well. The defects are produced by a three step mechanism involving nucleation, glide and reaction of Shockley partials on the {111} slip planes noncoplanar with the indented surface. We have observed that slip is in the directions along which the resolved shear stress has reached the critical value of approximately 2 GPa. The first yield occurs when the shear stresses reach this critical value on all the {111} planes involved in the formation of the defect. The phenomenon of strain hardening is observed due to the sessile stair-rods produced by the zipping of the partials. The dislocation locks produced during the second yield give rise to permanent deformation after retraction.Comment: 11 pages, 13 figures, submitted to Physical Review