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Progress on the studies of the material properties of the Homoptera’s wings

Date:2005-05-25Source:
The flight of insects has recently become an attractive research topic, for the sake of biomimetic design of the aerofoil of micro air vehicles. The material properties of the wings of insects are determined primarily by the need to optimize the production of favorable aerodynamic forces during flight. However, to-date the material properties of the wings of insects have never been systematically investigated so far. Dr. F. Song, a member of the research group leaded by Prof. Y.L. Bai of the institute of Mechanics of CAS, collaborated on the studies of the structural and mechanical properties of the forewings of cicadas with Prof. A.K. Soh’s group in the University of Hong Kong. By means of some experimental techniques, they obtained the relevant geometrical and physical characteristics of the forewings of cicadas. The main results are as the following. The measurement of the structures of the wings showed that the thickness of the membrane of each cell and the diameter of each vein were nonuniform in both the longitudinal and transverse directions, and their means were about 12.2 and 133.3mm, respectively. However, the aspect ratio of the wings and the bodies were quite uniform and were approximately equal to 2.98 and 2.13, respectively. Based on the measured thickness, weight and area of the membranes of the cells, the average density and the average area density of the wing were approximately 2.3 g/cm3 and 2.8´10-3 g/cm2, respectively. In addition, the diameters of the veins of the wings, including the diameters of the holes in the vein of the leading edge, were examined. The mechanical properties of the wing were investigated separately by nanoindentation and tensile testing. The results indicated that the average Young’s modulus, hardness and yield stress of the membranes of the wings were about 3.7GPa, 0.2GPa and 29MPa, respectively, and the average Young’s modulus and strength of the veins along the direction of the venation of wings were approximately 1.9GPa and 52MPa, respectively. Finally, the relevant results were briefly analyzed and discussed, which indicated that the optimization of the wing structures and the inter-cooperation of different materials that made the wings are directly associated with the flight capability and maneuverability of the insect. The results above provide a guideline to the biomimetic design of the aerofoil materials of micro air vehicles, and have been published in the Journal of Experimental Biology (Song, F., Lee, K.L., Soh, A.K., Zhu, F. and Bai, Y.L., Experimental studies of the material properties of the forewing of cicada (Homóptera, Cicàdidae), J. Exp. Biol., 2004, Vol.207: 3035-3042).