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Ren H.,Tsinghua University | Ren H.,Longyuan Beijing Wind Power Engineer Technology Co. | Wang X.,Tsinghua University | Li X.,Tsinghua University | And 2 more authors.
Journal of Bionic Engineering | Year: 2013

The configurations of dragonfly wings, including the corrugations of the chordwise cross-section, the microstructure of the longitudinal veins and membrane, were comprehensively investigated using the Environmental Scanning Electron Microscopy (ESEM). Based on the experimental results reported previously, the multi-scale and multi-dimensional models with different structural features of dragonfly wing were created, and the biological dynamic behaviors of wing models were discussed through the Finite Element Method (FEM). The results demonstrate that the effects of different structural features on dynamic behaviors of dragonfly wing such as natural frequency/modal, bending/torsional deformation, reaction force/torque are very significant. The corrugations of dragonfly wing along the chordwise can observably improve the flapping frequency because of the greater structural stiffness of wings. In updated model, the novel sandwich microstructure of the longitudinal veins remarkably improves the torsional deformation of dragonfly wing while it has a little effect on the flapping frequency and bending deformation. These integrated structural features can adjust the deformation of wing oneself, therefore the flow field around the wings can be controlled adaptively. The fact is that the flights of dragonfly wing with sandwich microstructure of longitudinal veins are more efficient and intelligent. © 2013 Jilin University. Source


Li X.-D.,Qingdao Campus of Naval Aeronautical Academy | Liu Z.-G.,Qingdao Campus of Naval Aeronautical Academy | Mu Z.-T.,Qingdao Campus of Naval Aeronautical Academy | Zhu W.-F.,Qingdao Campus of Naval Aeronautical Academy
Corrosion and Protection | Year: 2013

The fatigue crack growth behavior of LC9 aluminum alloy subjected to a transport aircratt loading spectrum was studied by immersing LC9 aluminum alloy in EXCO solution for different times to produce different degrees of corrosion damage. The results show that the corrosion damage can reduce the fatigue life of LC9 aluminum alloy severely. The depth of the corrosion pit was a suitable parameter for characterizing the corrosion damage and for predicting the fatigue life of LC9 aluminum alloy using commercial fatigue crack growth software. Source

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