Materials Science and Engineering Program, Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093-0418, United States.
J Mech Behav Biomed Mater. 2011 Jul;4(5):723-32. doi: 10.1016/j.jmbbm.2011.01.010. Epub 2011 Feb 4.
Mechanical characterization of the cortex of rectrices (tail feathers) of the Toco Toucan (Ramphastos toco) has been carried out by tensile testing of the rachis cortex in order to systematically determine Young's modulus and maximum tensile strength gradients on the surfaces and along the length of the feather. Of over seventy-five samples tested, the average Young's modulus was found to be 2.56±0.09 GPa, and maximum tensile strength was found to be 78±6 MPa. The Weibull modulus for all sets is greater than one and less than four, indicating that measured strength is highly variable. The highest Weibull moduli were reported for dorsal samplings. Dorsal and ventral surfaces of the cortex are both significantly stiffer and stronger than lateral rachis cortex. On the dorsal surface, cortex sampled from the distal end of the feather was found to be least stiff and weakest compared to that sampled from proximal and middle regions along the length of the feather. Distinctive fracture patterns correspond to failure in the superficial cuticle layer and the bulk of the rachis cortex. In the cuticle, where supramolecular keratinous fibers are oriented tangentially, evidence of ductile tearing was observed. In the bulk cortex, where the fibers are bundled and oriented longitudinally, patterns suggestive of near-periodic aggregation and brittle failure were observed.
已经通过对尾羽轴皮质的拉伸测试对托哥巨嘴鸟（Ramphastos toco）尾羽的皮质进行了机械特性研究，以便系统地确定表面和沿羽轴长度的杨氏模量和最大拉伸强度梯度。在测试的超过七十五个样本中，平均杨氏模量被发现为 2.56±0.09 GPa，最大拉伸强度被发现为 78±6 MPa。所有组的威布尔模数都大于一且小于四，表明测量的强度变化很大。报告的最高威布尔模数是来自背部采样。皮质的背侧和腹侧表面都比侧面轴皮质更硬且更强。在背侧表面上，与从羽轴长度的近端和中部区域取样的皮质相比，从羽毛末端取样的皮质发现硬度最小且强度最低。与断裂模式相对应的是在表皮层和轴皮质的大部分中发生的失效。在表皮中，超分子角蛋白纤维沿切线方向取向，观察到韧性撕裂的证据。在皮质的大部分中，纤维被捆绑并沿纵向取向，观察到接近周期性聚集和脆性失效的模式。
