考虑褶皱和三明治结构的蜻蜓翼自然频率及振型分析

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

为探究蜻蜓翼的优异结构进而对扑翼飞行器的设计提供技术借鉴,因此利用有限元法对蜻蜓翼二维模型、考虑褶皱和翅脉三明治结构的三维模型的自然频率及振型进行了分析。模态分析结果表明:褶皱结构可以显著提高蜻蜓翼的自然频率,翅脉的三明治结构会略微降低蜻蜓翼的抗弯、抗扭性能,考虑褶皱和三明治结构的蜻蜓翼一阶自然频率远大于蜻蜓的振翅频率,从而保证蜻蜓飞行不会发生共振现象。进一步分析了蜻蜓翼褶皱简化模型前三阶自然频率随起皱高度以及翅脉中蛋白质比例的变化曲线图,表明在一定范围内随起皱高度增大,模型各阶自然频率显著增加,但达到特定起皱高度后反而不利于模型的抗振性能。随着蛋白质层占比的增加,模型各阶频率呈递减的趋势,并以频率的下降快慢得到了蛋白质含量较佳的比例。本研究有助于解释蜻蜓翼的完美结构表现,并为扑翼设计提供借鉴。

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.