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Micro Hierarchical Structure and Mechanical Property of Sparrow Hawk (Accipiter nisus) Feather Shaf

Yichen Lu1, Zongning Chen1, Enyu Guo1,*, Xiangqing Kong2, Huijun Kang1, Yanjin Xu3, Rengeng Li4, Guohua Fan4, Tongmin Wang1,*

1 Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Engineering, Dalian University of Technology, Dalian, 116024, China
2 School of Civil Engineering, Liaoning University of Technology, Jinzhou, 121001, China
3 AVIC Manufacturing Technology Institute, Beijing, 100024, China
4 Key Laboratory for Light-Weight Materials, Nanjing Tech University, Nanjing, 211816, China

* Corresponding Authors: Enyu Guo. Email: ; Tongmin Wang. Email:

(This article belongs to this Special Issue: Recent Advances in Biomechanics and Biomimetic Mechanics)

Computer Modeling in Engineering & Sciences 2021, 127(2), 705-720.


In this study, the real 3D model of the feather shaft that is composed of medulla and cortex is characterized by X-ray computer tomography, and the structural features are quantitatively analyzed. Compression and tensile tests are conducted to evaluate the mechanical performance of the feather shaft and cortex at different regions. The analysis of the 3D model shows that the medulla accounts for ∼70% of the shaft volume and exhibits a closed-cell foam-like structure, with a porosity of 59%. The cells in the medulla show dodecahedron and decahedron morphology and have an equivalent diameter of ∼30 μm. In axial compression, the presence of medulla enhances the shaft stability. Especially, the combined effect of the medulla and cortex increases the buckling strength of the middle and distal shaft by 77% and 141%, respectively, compared to the calculated value of the shaft using linear mixed rule. The tensile properties of the cortex along the shaft axis are anisotropic because of the different fiber structures. As the fiber orientation gradually becomes uniform in the axial direction, the Young’s modulus and tensile strength of the cortex on the dorsal gradually increase from calamus to the distal shaft, and the fracture mode changes from tortuous fracture to V-shaped fracture. The cortex on the lateral shows the opposite trend, that is the distal shaft becomes weaker due to fiber tangles.


Cite This Article

Lu, Y., Chen, Z., Guo, E., Kong, X., Kang, H. et al. (2021). Micro Hierarchical Structure and Mechanical Property of Sparrow Hawk (Accipiter nisus) Feather Shaf. CMES-Computer Modeling in Engineering & Sciences, 127(2), 705–720.

This work is licensed under a Creative Commons Attribution 4.0 International License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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