Weiss Ingrid M, Kirchner Helmut O K
INM - Leibniz Institute for New Materials gGmbH, Saarbrücken, Germany.
J Exp Zool A Ecol Genet Physiol. 2010 Dec 1;313(10):690-703. doi: 10.1002/jez.641. Epub 2010 Sep 17.
The feathers in the train of the peacock serve not for flying but for sexual display. They are long, slender beams loaded in bending by their own weight. An outer circular conical shell, the cortex, is filled by a closed foam of 7.6% relative density, the medulla, both of feather keratin. Outer diameter and thickness of the cortex decrease linearly from the body toward the tip. This self-similar geometry leads to a division of labor. The cortex (longitudinal Young's modulus 3.3 GPa, transverse modulus 1 GPa) provides 96% of the longitudinal strength and bending rigidity of the feather. The medulla (Young's modulus 10 MPa) provides 96% of the transverse compressive rigidity. Fracture stress of the cortex, both longitudinal and transverse, is 120 MPa.
孔雀尾羽并非用于飞行，而是用于求偶展示。它们是细长的羽轴，因自身重量而承受弯曲载荷。羽轴外部是一个圆形圆锥壳，即皮质层，内部填充着相对密度为7.6%的封闭泡沫状物质，即髓质层，二者均由羽毛角蛋白构成。皮质层的外径和厚度从羽根向羽尖呈线性减小。这种自相似的几何结构导致了分工。皮质层（纵向杨氏模量为3.3吉帕，横向模量为1吉帕）提供了羽毛96%的纵向强度和抗弯刚度。髓质层（杨氏模量为10兆帕）提供了96%的横向抗压刚度。皮质层的纵向和横向断裂应力均为120兆帕。
