The Surface Hydrophobicty And The Finite Element Analysis On Structural Characteristics Of Cicade Wing

There are more than 10 million kinds of insects, accounting for 60% of all species, of which 95% have wings. In the evolutionary history of animals, insects are the very first animals that able to among fly and the only invertebrate ones can fly. After millions years of evolution, the wings possesses a variety of different functions, such as hydrophobic self-cleaning, anti-reflective, structural properties and material properties, as well as wonderful flying skills.Cryptotympana atrata Fabricius is a large insect among the flight ones, whose wings belong to Hymenoptera categories. The wings comprise of membrane and veins, which are thin and transparent, meanwhile have strong flight capacity and carrying capacity. The quality of cicada wings is equivalent to about 2/100 of overall body weightor (see section 5.2.1). Cryptotympana atrata Fabricius shows astonishing flying ability, through the wings'vein skeleton distribution as well as spatial structure. In this paper, we choosed the Homoptera Cicadidae of Cryptotympana atrata Fabricius as our study sample, collected from Linyi (Shandong, China).It used the OCA20 video optical contact Angle measuring instrument determinates the contact angles of the upper and lower Cryptotympana atrata Fabricius hymenopteras. In order to reduce the effect of the factor that different contact angles in different regions, we choose 10 Cryptotympana atrata Fabricius superior wings, and divide each wing is into three zones, respectively measuring, came to the conclusion that that the arithmetic mean±standard deviation of the overall contact angle on the upper wings is 145.01±1.4o at last.It used the JSM-5600 scanning electron microscope (SEM) to observation the upper Cryptotympana atrata Fabricius hymenopteras on the direction of overlooking and strabismus, found that the existence of columnar papillae structure in regular arrangement on the surface of cicada wings: Head of papillae was hemispheric body, the radius of the connection papillae root attach to epidermis was increasing, and the distance papillae btween each others approximate equal. The columnar papillae structure geometric parameters: The radius of papillae head R1=38.8829±3.01nm; the radius of papillae head bottom R2=72.3856±5.27nm; the distance papillae btween each others e=179.4412±15.12nm, Top high of columnar papillae h1=159.1191±12.22nm, The lower of columnar papillae h=53.0397±4.12nm.It used Wenzel and Cassie model to make an examination on hydrophobic mechanism of nano-scale columnar papillae on the structure of Cryptotympana atrata Fabricius hymenopteras, concluded that: theoretical contact angle based on the Wenzel model =132.0971o, 8.97% lower than the actual measured contact angle;whereas the theoretical contact angle based on the Cassie model Coincide with the actual measured measured contact angle. Based on Cassie model, we can conclude that: the Strong hydrophobic of the Cryptotympana atrata Fabricius hymenopteras due to the rough surface built by the regular nano-scale columnar papillae structure, and among papillaes, it adhere to air film to constitute a three-phase composite contact surface, which further induced the surface hydrophobicity of cicada wings.It used LSV50 three-dimensional laser scanning system to obtain the date of the upper and lower Cryptotympana atrata Fabricius Hymenoptera, and used sofeware Imageware to do noise removing, visualization and date reducing. Used the curve-fitting surface method and the point cloud surfaces method to Fit three-dimensional reconstructional model. Comparison the result error of two methods. Finally, choosed the Point Cloud Surfaces Method, The modeling result error: for the upper hymenoptera, the maximum Euclidean error is 0.0655mm, the average Euclidean error is 0.0063mm; the maximum Euclidean error of the lower hymenoptera is 0.0569mm, the average Euclidean error is 0.0054mm.Do smoothing treatment on the upper and lower hymenopteras, using surface seflection analysis and gaussian curvature analysis in the UG software to checkout the surface smoothness. For the former of Hymenoptera, surface smoothness is well, the maximum gaussian curvature is 0.0093mm-2, the minimum gaussian curvature is 0.010mm-2. For the back of Hymenoptera, the surface smoothness is well except the expansion parts.It used finite element software ANSYS do structural statics and modal analysis on Cryptotympana atrata Fabricius Hymenopteras. Introduced the former and back Hymenoptera model of Reverse Engineering into ANSYS, used Shell43 element to simulate membrane and Beam189 element to simulate vein, established element parameters and attributes according to the scanning electron microscopy photos for cicada wings section and relevant literatures.a. Executing structure linear Statics analysis on the former and back of Hymenoptera model, the boundary and load conditions: fixed the base of cicada wing, imposed gravity uniform load (P=1518.52bN/dmm2)the surface of Cryptotympana atrata Fabricius hymenoptera models. We can utilize the result of analysis to understand the basic deformation and axial stress of the upper and lower Hymenoptera under the graviry uniform load. the results showed that cicada wings appeared geometrical large distortion non-linear characteristics.b. Considering the factor of geometrical non-linear large distortion. Carry non-linear static structural analysis on the upper Cryptotympana atrata Fabricius hymenoptera model, choosing of 14 observation points from the results of linear static structural analysis., mainly on the structural displacement, veins parameters such as axial stress and bending moment. Using UG establish 5 models and 2 group comparison tests on veins structural factors and 4 models and 2 group comparison tests on membrane structural factors, the boundary and load conditions: fixed the base of cicada wing, imposed gravity uniform load (P=1518.52bN/dmm2)the surface of Cryptotympana atrata Fabricius hymenoptera model, obtained the following conclusions:Structural characteristics of veins: the impression of Media vein M on the stiffness of the Hymenoptera model is not significant, it can make axial force of Reticular formation veins conduction more evenly, and reduce the axial stresses of Leading edge veins Sc + R and Anal vein A; Cubitus vein Cu and Anal vein A has significantly contributed to the increase of the stiffness of the Hymenoptera model, except shouldering a greater stress axis; Cryptotympana atrata Fabricius Hymenoptera reticular formation veins have a excellent anti-bending performance, the bending rigidityof wing with veins and membraneis 5-6 times than the wing with only membrane; size distribution of natural veins no only effectively increase the stiffness of Hymenoptera structure , but also ensure the uniform distribution of veins bending moment, and uniformity of axial force conduction.Structural characteristics of membrane: the three-dimensional Cryptotympana atrata Fabricius hymenoptera structure has a better bending rigidity than the planar structures', which was mainly due to hymenoptera archs camber in the natural state. However, Increasing the camber of the Cryptotympana atrata Fabricius Hymenoptera medol will also lead to a negative impact: enhancing the axial stress of veins , especially the veins near the horizontal symmetry line of Hymenoptera.c. Executing modal analysis on the upper and lower Cryptotympana atrata Fabricius Hymenoptera medoles, mainly on the top 5 order natural vibration frequency and vibration model. Using UG establish 7 models and 2 group comparison tests mainly on the veins,membrane structure factors and the comparison between the upper and lower Cryptotympana atrata Fabricius Hymenoptera modals, obtained the following conclusions:Reticular formation veins structure of Cryptotympana atrata Fabricius wing is conducive to enhancing the natural frequencies of the model, the natural frequency of the Cryptotympana atrata Fabricius wing three-dimensional structure model (56.67Hz) is higher than the planar models'(26.40Hz), the vibration frequency of the flapping wing micro air vehicle wing btween 20-25Hz [82], in the design work of Biomimetic Flapping-Wing Micro Air Vehicle it tips us that: design the wing to be the biomimetic wing surface in order to prevent fatigue resonance of the wing structure, Increasing the camber of cicada wing model will lead to the enhancement of the natural frequencies, the upgrading percentage of the natural frequenciesl is approximately equal to the upgrading percentage of the model camber,the first, second and third order vibration mode of the upper and lower Cryptotympana atrata Fabricius hymenoptera models are very similar, while the first-order natural frequencies are only a difference of 1.49Hz (the upper 56.67Hz , the lower 58.16Hz), as a result of a long-term natural evolution.