Microstructures and Mechanical Properties of the Feather Rachis
| Autor: | Tse-yu Lin, 林則余 |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 Feathers are the most complex integumentary appendage found in nature. The complex feather regeneration leads to its hierarchical branching, highly organized inner-outer structure, and multifunction in avian daily life. The feather has become an important topic in modern interdisciplinary research field. In contrast to early anatomy research of feathers, the excavation of prehistoric dinosaur feather fossils have inspired scientists to explore feathers in the perspective of evolution and regeneration recently. The novel feather development model and the confirmation of crucial biochemical signals during feather morphogenesis are important milestones in the modern feather research. The feather regeneration in an asymmetric avian follicle makes the composition of a feather exhibits non-uniform material properties. However, former researchers rarely investigate how the non-uniform composition of feather may contribute to its mechanical properties. In this thesis, we investigate the effect of non-uniform inner microstructure in the feather rachis among species, and study the influence of microstructure on rachis mechanical properties. We use a home-made bending test system to measure the bending elastic modulus of the rachis medulla and cortex in different bending direction. The result indicates that the non-uniform microstructure of the porous medulla from a single species do not introduce the anisotropy of the elastic modulus. However, the measured elastic modulus of medulla have a distinctive difference among feathers from various species. We also investigate the influence of the moisture to the rachis microstructure in order to understand the impact of the dehydration during feather development microscopically. We use the fluorescent microscopy to observe the morphology of medulla and cortex during hydration and dehydration of the rachis. We observe the swelling of the feather rachis associated with the hydration. The rachis prefer expanding anisotropically towards the barbs direction. The hydrated rachis medulla without cortex tends to expand perpendicularly to the direction of microstructure pattern. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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