Research Of Biomimetic Foldable Wing Based On The Beetles Hind-wing

Micro Air Vehicle(MAV) has incomparable advantage than other aircraft when executing the task under tight spaces or complex terrain conditions, because its characteristics of small in size, easy to carry, good operation and strong concealment. With further reduction in size, the flapping-wing MAV showed more obvious advantages in maneuverability, propulsion efficiency and aerodynamic performance, which makes it an important direction for future development of the MAV. The wings of flapping-wing MAV must be light enough in order to reduce the total weight, so the membranous wing which is similar to the insect wings has been adopted. However, the membranous wing is very fragile and easy to damage.The beetles’ membranous hind-wings can be folded under the elytra when they have a rest, and be unfolded when flying. This characteristic makes it possess excellent flying ability and good environmental adaptability. Inspired by beetles, a new type of bionic foldable wing for the flapping-wing MAV was designed in this paper. This flapping wing can be expanded to get enough lifting force in flight, and can be folded up when not flying to reduce the wing area, to decrease the risk of damage to the wing.The folding/unfolding process and mechanism of beetles’ hind-wing is analyzed based on previous research in this paper. Several wings of Dorcus titanus platymelus in different unfolding state are scanned by using the SKYSCAN 1176 IN-VIVO MICRO-CT, and reconstruct its three-dimensional model. By analyzing the morphological changes of the unfolding process of beetles’ hind-wing, found that the unfolding process of the beetles’ hind-wing can be divided into two phases. In the first phase, the morphological changes of the wing tips mainly fan out around the central part of the wing, and in the second phase, the wing expanded longitudinally. The study also found that the hind-wing expanded from a complex three-dimensional structure to plane structure during the unfolding process.Based on the hydraulic mechanism and the morphological changes during the wing unfolding process, a bionic wing was designed which can be folded and unfolded driven by hydraulic. The relationship between the pressure of the bionic wing folding hydraulic and temperature was analyzed, the results show that the hydraulic pressure within the system tends to increase with the increase of temperature, which prove the feasibility of the design scheme in theory. An unfolding test by a bionic wing prototype was conducted in order to further verify the feasibility of the design scheme. Although the results do not meet expectations, the prototype shows a trend of unfolding clearly, which further proved the feasibility of the design. The reasons of deviations occurring in the test results were analyzed in this paper.The stress analysis of the bionic foldable wing was also conducted in the paper, the results showed that stress distribution and deformation of bionic wing in the positive and negative side loading are basically same, but there is a big difference between the bionic wing model and the three-dimensional model which imitated the Dorcus titanus platymelus’ hind-wing(Model Ι). The stress and strain in the bionic wing model are smaller than the Model Ι under the same load, which demonstrates that the strength of the bionic folding wings meet the requirements.In summary, a new bionic foldable wing for the flapping-wing MAV based on the Dorcus titanus platymelus’ hind-wing was designed in this paper. And the feasibility is proved from theory and experiment. The research work in this paper play an important role in reducing the size of carry flapping wing MAV, reducing the risk of damage to wing flapping, and increasing the service life of MAV.