Investigation of Natural Frequencies and Vibration Modes of Dragonfly Wing Considered Sandwich、Zigzag Cross-section Structure

In order to explore the excellent structure of dragonfly wing and to provide technical reference for the design of flapping wing aircraft, the natural frequency and vibration mode of 2D model、3D model and the 3D model considered sandwich structure of dragonfly wing were analyzed by means of finite element method in this paper. Modal analysis results showed that the zigzag cross-section structure can significantly improve the natural frequencies of the dragonfly wing, sandwich structure had slightly negative effect on dynamic performance. The first nature frequency of 3D model is much larger than the flapping frequency of the dragonfly, so resonance damage will not occur. Then a group of simplified model of dragonfly wing was established and the first three natural frequency curves with the wrinkling height and protein ratio in the vein were drawed. As the wrinkling height increased in a certain range, the natural frequency of the model increased gradually. While the protein layer's ratio enlarged, the frequency of the model decreased significantly, the optimal ratio of protein was obtained. This research is helpful in answering why insect wings are so impeccable. The research provided possibility of improving the design of flapping-wing aerial vehicles.