Dragonfly Wing Research Articles

Aerodynamic Effects of Time-Varying Corrugations on Dragonfly Wings in Flapping Flight.

The aerodynamic effects of wing corrugation on insect flight have received widespread attention. However, there has hardly been any specific focus on dynamic changes to corrugation angle in the models. The flexible vein joints containing resilin in the wings of dragonflies and damselflies enable the longitudinal veins to rotate and thereby change the corrugation angles throughout flapping cycles. Therefore, a two-dimensional corrugated airfoil with time-varying corrugation angles is proposed and the aerodynamic performance is evaluated in terms of aerodynamic force, power and efficiency. The results indicate that the airfoil with time-varying corrugations outperforms the rigid one in terms of enhancing thrust and reducing power consumption. The aerodynamic performance of time-varying corrugated airfoils is optimal when the angle varies in a specific range, and an excessively large angle variation may have negative effects. In addition, excessive height or a negative leading edge of the corrugation can lead to a reduction in the thrust. A design concept for the 2D airfoil with time-varying corrugations is provided and the findings are of significance for enhancing the aerodynamic performance of biomimetic flexible flapping-wing vehicles.

A novel dragonfly wing shape auxetic tubular structure with negative Poisson’s ratio

Mechanical structures abilities to absorb and dissipate energy have a variety of applications in daily life, including the ability to dampen mechanical vibrations and shock effects. In the present study, inspired by the dragonfly wing (DFW) shape, a novel auxetic unit cell was developed with the goal of proposing a novel structure with a lower stress concentrator and consequently increasing energy absorption. The negative Poisson’s ratio behavior was also studied. The DFW shaped unit cells were applied in a tubular structure, and the experimental samples were produced utilizing an additive manufacturing process with polylactic acid filament. To validate the ability to absorb energy of the novel unit cell, a comparison was proposed with the classical reentrant auxetic tubular structure following two different parameters: weight and the number of unit cells being developed in two different DFW structures. The study of the novel unit cell was performed using finite element analysis and experimental testing, and excellent agreement was observed between them. As a result, the bio-inspired DFWs shape in both configurations proposed when compared to the classical reentrant presented an excellent result in terms of absorbing energy, where the structure with the same quantity of unit cells and the structure with the same weight respectively absorb 163% and 79% when compared to the classical Reentrant, finally the new structure presented the negative Poisson’s ratio of −0.5, presenting an auxetic behavior and being able to resist more force and displacement

Soft nanotechnology: Used as a functional coating on a nanostructured germicidal surface

Bacterial contamination has emerged as a significant threat to human health over the past century. Initially, antibiotics were seen as the solution to this problem, but their overuse has led to the development of drug resistance and the rise of superbugs. These superbugs are resistant to most, if not all, conventional antibiotics, making them particularly difficult to treat. Interestingly, research has shown that the wings of dragonflies and cicadas possess natural nanopillar structures that are capable of inhibiting bacterial growth. These nanopillars puncture bacterial cell membranes, leading to bacterial death. This discovery has opened up new avenues for combating bacterial contamination. Recent advancements in soft nanotechnology have introduced innovative antibacterial coatings that are crucial for combating these antibiotic-resistant superbugs. These coatings work by mimicking the nanopillar structures found on the wings of dragonflies and cicadas. Understanding the interaction between bacteria and these nanoantibacterial coatings is essential for achieving effective bactericidal outcomes. Different bacteria require varying optimum aspect ratios, which can be achieved through various formation methods. Therefore, this paper elucidates the principles of soft nanocoating, with a focus on comparing aspect ratios obtained through different preparation techniques and, according to the different aspect ratio, determining the corresponding applicable sterilization scene. It also explores the practical application of nanostructure bactericidal surface coatings to address the growing threat of antibiotic resistance and enhance public health. Moreover, as an emerging field, this paper examines the challenges in soft nanocoating applications and the directions that can be improved in the future. The versatility and potential of soft nanotechnological coatings seems to apply to various industries, promising enhanced performance and safety standards. This is a crucial step towards creating a safer and healthier future for all.

Analysis of fluid-structure coupling during the flapping of dragonfly hind wings under different flexible distributions

Abstract To investigate the influence of flexible distribution on the aerodynamic characteristics of a dragonfly hind wing during flapping flight, this study establishes a simplified plate model of the dragonfly hind wing based on the actual size, while neglecting the wrinkled microstructure. Six different flexible distribution patterns are proposed for the model. The overlapping grid technique is employed to achieve fluid-structure coupling calculations during the flapping motion of the dragonfly hind wing, by customizing the Young’s modulus in the solid region to represent different levels of flexibility. The results show that gradually increasing the flexibility along the chordwise direction of the dragonfly wing can induce a stronger leading-edge vortex during flapping, intensifying the accumulation of vorticity near the wingtip and resulting in a higher peak lift coefficient. The flexible wing has a positive impact on the formation and development of the trailing-edge vortex, leading to an increase in the thrust coefficient peak and time-averaged thrust coefficient of the dragonfly hind wing. Consequently, all aspects of the aerodynamic characteristics are significantly improved.

Research of biomimetic corrugation on the blade flutter suppression in large-scale wind turbine systems

Aiming at the blade flutter of large horizontal-axis wind turbines, a method by utilizing biomimetic corrugation to suppress blade flutter is first proposed. By extracting the dragonfly wing corrugation, the biomimetic corrugation airfoil is constructed, finding that mapping corrugation to the airfoil pressure side has better aerodynamic performance. The influence of corrugation type, amplitude λ, and intensity on airfoil flutter is analyzed using orthogonal experiment, which determines that the λ has the greatest influence on airfoil flutter. Based on the fluctuation range of the moment coefficient ΔC m, the optimal airfoil flutter suppression effect is obtained when the type is III, λ= 0.6, and intensity is denser (n = 13). The effective corrugation layout area in the chord direction is determined to be the leading edge, and the ΔC m of corrugation airfoil is reduced by 7.405%, compared to the original airfoil. The application of this corrugation to NREL 15 MW wind turbine 3D blades is studied, and the influence of corrugation layout length in the blade span direction on the suppressive effect is analyzed by fluid-structure interaction. It is found that when the layout length is 0.85 R, the safety margin S f reaches a maximum value of 0.3431 Hz, which is increased 2.940%. The results show that the biomimetic corrugated structure proposed in this paper can not only improve the aerodynamic performance by changing the local flow field on the surface of the blade, but also increase the structural stiffness of the blade itself, and achieve the effect of flutter suppression.

Tough, Waterproofing, and Sustainable Bio‐Adhesive Inspired by the Dragonfly Wing

AbstractThe development of multifunctional bio‐adhesive plays a critical role in achieving a sustainable society, where the intrinsic sensitivity to water and poor dynamics severely bottlenecks its scale‐up application. Inspired by the microstructure of dragonfly wings, a strong and tough adhesive with excellent reprocessability is designed and developed by creating a dynamic network consisting of a lignin polyurea (LPU) framework with soybean protein (SP). The LPU framework act as the rigid nervures to slow crack propagation and transfer stress, while the SP dissipate the strain energy through the interplay from the graded hydrogen and imine bonds generated between LPU and SP. The bio‐adhesive achieves significant enhancements in fracture toughness and water resistance by ≈7 and 23 folds, respectively, compared with SP. Furthermore, the capacity for diffusion and restoration of dynamic network endows the adhesive with superior reprocessability, enabling recycled particleboard to achieve high retention of modules (over 80%). This sustainable bio‐adhesive approach offers a promising eco‐friendly alternative to the conventional petrochemical adhesive.

Aerodynamic performance of a flyable flapping wing rotor with dragonfly-like flexible wings

Drawing inspiration from insect flapping wings, a Flapping Wing Rotor (FWR) has been developed for Micro Aerial Vehicle (MAV) applications. The FWR features unique active flapping and passive rotary kinematics of motion to achieve a high lift coefficient and flight efficiency. This study thoroughly investigates the aerodynamic performance and design of a bio-inspired flexible wing for FWR-MAVs, emphasizing its novel backward-curved wingtip and variable spanwise stiffness resembling a dragonfly's wing. The research departs from previous aerodynamic studies of FWR, which focused predominantly on rectangular and rigid wings, and delves into wing flexibility. Employing Computational Fluid Dynamics (CFD), Computational Structural Dynamics (CSD), and experimental measurements, the study demonstrates the aerodynamic benefits of the dragonfly-inspired FWR wingtip shape and its reinforced structure. Fluid-Structure Interaction (FSI) analysis is used to examine the effects of elastic deformation encompassing twist and bending on aerodynamic forces. The results underscore the importance of bending deformation in enhancing lift and power efficiency and propose a method for analysing variable stiffness along the wingspan using a vortex delay mechanism that is induced by delayed flapping motion. By comparing modelled and measured stiffness, the study validates the flexibility of the FWR wing, revealing optimal aerodynamic efficiency is achieved through moderate flexibility and spanwise stiffness variation. The curving leading-edge beam forming the sweep-back wingtip offers a practical approach to obtaining variable stiffness and aerodynamic benefits for FWR-MAVs. Using the same pair of dragonfly-like flexible wings, FWR-MAVs have effectively exhibited VTOL and hovering flight capabilities, spanning from a 25-g single-motor drive model to a 51-g dual-motor drive model. This research provides valuable insights into flexible wing design for FWR-MAVs, leveraging biomimicry to improve flight efficiency.

Desirable Strong and Tough Adhesive Inspired by Dragonfly Wings and Plant Cell Walls.

The production of wood-based panels has a significant demand for mechanically strong and flexible biomass adhesives, serving as alternatives to nonrenewable and toxic formaldehyde-based adhesives. Nonetheless, plywood usually exhibits brittle fracture due to the inherent trade-off between rigidity and toughness, and it is susceptible to damage and deformation defects in production applications. Herein, inspired by the microstructure of dragonfly wings and the cross-linking structure of plant cell walls, a soybean meal (SM) adhesive with great strength and toughness was developed. The strategy was combined with a multiple assembly system based on the tannic acid (TA) stripping/modification of molybdenum disulfide (MoS2@TA) hybrids, phenylboronic acid/quaternary ammonium doubly functionalized chitosan (QCP), and SM. Motivated by the microstructure of dragonfly wings, MoS2@TA was tightly bonded with the SM framework through Schiff base and strong hydrogen bonding to dissipate stress energy through crack deflection, bridging, and immobilization. QCP imitated borate chemistry in plant cell walls to optimize interfacial interactions within the adhesive by borate ester bonds, boron-nitrogen coordination bonds, and electrostatic interactions and dissipate energy through sacrificial bonding. The shear strength and fracture toughness of the SM/QCP/MoS2@TA adhesive were 1.58 MPa and 0.87 J, respectively, which were 409.7% and 866.7% higher than those of the pure SM adhesive. In addition, MoS2@TA and QCP gave the adhesive good mildew resistance, durability, weatherability, and fire resistance. This bioinspired design strategy offers a viable and sustainable approach for creating multifunctional strong and tough biobased materials.

Novel Skin-Reinforcement Design by Cross–Longitudinal Layout Inspired by Dragonfly Wing

The objective of this study is to develop a novel aircraft design approach using biomimetics as an alternative to traditional airframes. This approach is primarily inspired by the dragonfly wing, which possesses reinforcement structures composed of cross veins and longitudinal veins. These structures are assumed to regulate deformation and enhance stiffness, respectively. The cross veins were replicated using weighted centroidal Voronoi tessellation (WCVT) based on the out-of-plane displacement of the skin. In contrast, the longitudinal veins were replicated by extracting a centerline from the topology optimization (TO) results on the skin, achieved through image analysis techniques such as binarization and skeletonization. The longitudinal layout effectively reduces compliance by distributing internal loads, utilizing only essential reinforcements on the skin without increasing its mass. The WCVT layout significantly enhances the buckling resistance of the reinforced skin. As a result, the skin reinforced using both cross–longitudinal layouts from TO and WCVT exhibited a buckling load 2.7 times greater while maintaining a lower mass compared to conventional layouts.

Effects of kinematic parameters and corrugated structure on the aerodynamic performance of flexible dragonfly wings

The effects of unsteady motions of flapping flat plates and corrugated structures in different parameters are studied using fluid–solid coupling and overlapping grid methods. Based on the dragonfly’s right forewing and right hindwing model, these actions include sweeping and pitching, take-off acceleration, and tandem wings cruising in the reverse phase at 180°. The results show that when the advance ratio J=0.36, the “inflow deflection” improves the aerodynamic force in two degrees of freedom compared to simple flapping. When considering only the impact of flexibility, the aerodynamic forces of flexible flat plates and corrugated structures are better than those of the rigid wing models. Considering the effect of corrugated structures, the lift of flexible corrugated wings diminishes, but more thrust is generated. From the perspective of vortex street, vortex rings materialize only in the downstroke stage, while the attachment effect of leading-edge vortices is noticeable in several models. In the same phase flapping, the two wings combine to form a giant wing, which generates significant forward flight momentum. In out-of-phase flapping mode, the series wings generate two lifts and two or three thrust peaks to attain the required forward flight speed while sustaining a high lift.

Effect of Blood Circulation in Veins on Resonance Suppression of the Dragonfly Wing Constructed by Numerical Method

Effect of Blood Circulation in Veins on Resonance Suppression of the Dragonfly Wing Constructed by Numerical Method

Study on Miura Folding Technology and Its Application in Sound Insultation

Based on the wings of dragonflies, Japanese astrophysicist Koryo Miura invented a new folding technology called Miura folding. The core principles of Miura folding include symmetry, periodicity, and compactness. The structure of Miura folding is arranged alternately by multiple parallel creases, which can remain stable when unfolding and folding. The Miura folding has the advantages of compactness, speed, structural stability, mathematical controllability, and multi-field application. Compared with traditional methods, the Miura folding provides more efficient, flexible, and more controllable solutions for a variety of application scenarios, from space technology to practical tools in daily life. This article reviews the origin and advantages of Miura folding and discusses its applications, focusing on the design and innovation of Miura folding sound insulation walls. The progress in design, the challenges related to the control of sound insulation, and the sound insulation of Miura folding are discussed. In addition, this article also discusses the application of Miura folding in other fields, the application of Miura folding technology in the era of globalization, and the prospect of future Miura folding technology in the emerging technology field. This article may offer a reference for the development of folding technology.

DYNAMIC BEHAVIOR OF DRAGONFLY WING VEINS INCLUDING THE ROLE OF HEMOLYMPH

Due to some outstanding properties of dragonfly wings, such as a lightweight structure with good aerodynamic performance, they have attracted the attention of many researchers. The microscopic and macroscopic structures of dragonfly wings play important roles in their behaviors. One of these structures that are spread all over the wing is vein. In this study, as the first endeavour, the geometric characteristics of the vein are modeled precisely, and the natural frequencies of it are calculated. Next, the vibration of the vein with considering structural damping, stationary and moving hemolymph is investigated. In the cases where hemolymph is considered, the influences of fluid–structure interaction (FSI) of hemolymph on the vibrational behavior of wing vein are included. To show the accuracy of the used methodology, the present model is compared with the microscopic image of the vein. Besides, some comparisons with theoretical and experimental findings are also proposed.

Machine learning-driven multi-level composite SERS platform for trace detection of chlorogenic acid as pharmacodynamic substance in honeysuckle

We reported a multi-level composite SERS platform which could provide a new method for accurate and quantitative trace detection for pharmacodynamic substance in traditional Chinese medicine (TCM). Using natural dragonfly wings as the template, Ag NPs were deposited on V-Ti nano-columns through controllable magnetron sputtering technology. Ag30@V-Ti20@D.W possessed a uniform nanostructure and exhibited High-performance SERS signal sensing capability. The detection limit (LOD) of R6G was 1 × 10−10 M. Through machine learning, we accurately classified and recognized R6G at different concentrations. The multi-level composite structure provided a wide range of “hot spots” areas and ensured good reproducibility with a relative standard deviation (RSD) value of 7.13%. When quantitatively detected chlorogenic acid, an active ingredient in honeysuckle, LOD value of 1 × 10−6 g/l was obtained. In the future, the combination of SERS spectroscopy technology and machine learning will provide theoretical and experimental support for the development of new strategies for detecting Other pharmacodynamic substances in TCM.

Investigation of the antiadhesive properties of biomimetic titanium nanostructures in fluidic flow

Abstract Within this work, the bacterial adhesion on biomimetic titanium nanostructures is investigated in fluidic flow. The motile, gram-negative bacteria strain Escherichia coli was used for the experiments and was incubated on nanostructured titanium, polished titanium and on the wings of the dragonfly Neuorbasis kaupi. After incubation period different flow velocities have been applied and the reduction of adhered bacteria was determined via fluorescence microscopy. Results show that nanostructured titanium surfaces have the ability to reduce the bacterial contamination as it is for the dragon fly wings used in this study. This behavior can also be predicted by analyzing the bearing area of the nanotopography which describes the actual part of the topography which is in contact to the bacteria.

Bio-Inspired Deformable Propeller Concept for Smooth Human-UAV Interaction and Efficient Thrust Generation

This letter presents a novel deformable propeller concept, 3D-printed in flexible thermoplastic polyurethane, which stores impact energy in the form of elastic energy for smooth collisions, reducing risk in human-UAV interactions. However, such a design experiences elastic deformations when exposed to aerodynamic and centrifugal loads. The most relevant occur in the 3-5 krpm range. At higher speeds, the centrifugal force is dominant and the propeller becomes quite stiff. This work provides an investigation of the propeller deformation angles (which ultimately alter the aerodynamic profile and limit thrust generation) based on Fluid-Structure Interaction (FSI) simulations. These results are leveraged to introduce two complementary solutions: deformation reduction oriented internal fiber distributions, inspired by the ultra-efficient dragonfly wings (I); anticipatory designs which pre-modify pitch and roll angles based on simulation results to ensure optimal performance at the target rotational velocity (II). This letter offers a multi-configuration analysis, yielding an easy to manufacture propeller with a specific design methodology which results in increased efficiency and reduced impact recovery time. This work presents collision tests with various objects, as well as a proof of concept for its flight capabilities in a conventional quadrotor, including physical interaction with humans. These findings are valuable for the development of collision control strategies for UAVs.

Highly Transparent Carbon Nanofibrous Membranes Inspired by Dragonfly Wings.

Carbon nanofibrous membrane (CNFM) materials are commonly black and opaque, and their poor optical performance severely limits their application in emerging fields, such as electronic skin, wearable devices, and environmental technologies. However, it is extremely difficult for carbon nanofibrous membranes to achieve high light transmittance owing to their complex fibrous structures and high light absorption. Few researchers have studied transparent carbon nanofibrous membrane (TCNFM) materials. In the current study, a biomimetic TCNFM inspired by dragonfly wings is fabricated using electrospinning technologies and a self-designed patterned substrate, with the aim to construct a differential electric field. Compared with the disordered CNFM, the resultant TCNFM yields an approximately 18-fold higher light transmittance. The freestanding TCNFMs also exhibit high porosities (>90%), good flexibility, and good mechanical properties. The mechanism by which the TCNFMs achieve high transparency and reduce light absorption is also elucidated. In addition, the TCNFMs display a high PM0.3 removal efficiency (>90%), low air resistance (<100 Pa), and good conductive properties, including a low resistivity (<0.37 Ω·cm).

Dragonfly-Inspired Wing Design Enabled by Machine Learning and Maxwell's Reciprocal Diagrams.

This research is taking the first steps toward applying a 2D dragonfly wing skeleton in the design of an airplane wing using artificial intelligence. The work relates the 2D morphology of the structural network of dragonfly veins to a secondary graph that is topologically dual and geometrically perpendicular to the initial network. This secondary network is referred as the reciprocal diagram proposed by Maxwell that can represent the static equilibrium of forces in the initial graph. Surprisingly, the secondary graph shows a direct relationship between the thickness of the structural members of a dragonfly wing and their in-plane static equilibrium of forces that gives the location of the primary and secondary veins in the network. The initial and the reciprocal graph of the wing are used to train an integrated and comprehensive machine-learning model that can generate similar graphs with both primary and secondary veins for a given boundary geometry. The result shows that the proposed algorithm can generate similar vein networks for an arbitrary boundary geometry with no prior topological information or the primary veins' location. The structural performance of the dragonfly wing in nature also motivated the authors to test this research's real-world application for designing the cellular structures for the core of airplane wings as cantilever porous beams. The boundary geometry of various airplane wings is used as an input for the design proccedure. The internal structure is generated using the training model of the dragonfly veins and their reciprocal graphs. One application of this method is experimentally and numerically examined for designing the cellular core, 3D printed by fused deposition modeling, of the airfoil wing; the results suggest up to 25% improvements in the out-of-plane stiffness. The findings demonstrate that the proposed machine-learning-assisted approach can facilitate the generation of multiscale architectural patterns inspired by nature to form lightweight load-bearable elements with superior structuralproperties.

Numerical Design of the Roof Structure of a Vehicle Charging Carport Based on the Dragonfly Wing Grid Pattern

The realization of the global “Double carbon” target is closely related to the energy-saving travel of human beings. Along with the increase in the number of new energy vehicles around the world, the number of new energy vehicle charging post carports has also increased. However, the collapse of the carport of the new energy vehicle charging post often occurs. The search for ways to optimize the carport structure construction and build a lighter and more stable charging post carport structure has become one of the hot spots in the new energy vehicle industry. Dragonfly wings have a comprehensive evolution in structure, form and function, and their stiffness, stability and resistance to deformation may be a potential solution to optimize the structure of the shed roof. Inspired by this, the study designs two new energy vehicle charging pile canopies based on the dragonfly wing mesh structure to enhance the loading capacity and structural stability of the canopies. The study firstly concludes that the dragonfly wing mesh can enhance the stiffness through experimental analysis, and simulates and models the structure based on the quadrilateral mesh wrinkling and hexagonal mesh arching in its mesh morphology, combined with the national design standard of the charging pile canopy. Studies on the numerical design experiment of the new energy vehicle charging station canopy model based on finite element software under different natural loads, the deflection of shed under the action of self-weight and the deflection, tensile stress and compressive stress under external load are analyzed, and the results show that: (1) The grid structure of the dragonfly wing bionic charging pile shed can optimize the stiffness of the car charging pile shed. (2) According to the wing structure, the test results of the shed roof structure under different working conditions are better than the national standard. (3) Compared with the vertical load, the transverse load of the arched membrane structure, which is represented by the charging pile shed of the new energy vehicle, is larger. (4) According to the stress point of the shed, the structure constraint of the shed can effectively reduce the pressure on the and share part of the load, which can enhance the stability of the shed. (5) In comparison with the displacement of common carport types, the bionic carport shows superior stability and durability. The new bionic carport structure proposed by the research, with stronger pressure bearing, smaller force deformation and lighter weight, is a kind of membrane structure for stable new energy vehicle charging pile carports, which will help further the optimization and promotion of the new energy vehicle industry.

Bionic Mechanical Analysis of Dragonfly Wings: The Feasibility of Mesh Combination to Improve Structural Stiffness

The nodes of the object will show different degrees of deformation and displacement or even damage over time. The mesh structure is flexible and different mesh shapes and arrangements will affect the structural stiffness of the object. The unique structure of dragonfly wing veins allows the dragonfly to withstand pressures several times higher than itself and to fly freely. This study is based on dragonfly wing bionics to disassemble the structure of dragonfly wing vein geometry. And it aims to investigate the deflection under different geometries and three-dimensional spatial structures by using the drawing software Auto CAD to draw dragonfly sample graphics, the finite element software Hyper mesh to build the model and the solver OptiStruct to analyze the structure of wrinkling, arching deflection, z-direction maximum displacement, y-direction maximum rotation angle, combined displacement test under the different loads. The results show that: (1) The dragonfly wing vein mesh structure can enhance the stiffness under load. (2) In contrast, the displacement deformation of quadrilateral and combined hexagonal is smaller. (3) The structural stiffness of quadrilateral hexagon is enhanced as the height of wrinkling and arching increases. (4) The improvement of grid deflection with membrane structure is better than that without membrane structure. According to the above experimental results, the quadrilateral wrinkling and hexagonal arching structure has a significant improvement on the load bearing and deflection of the mesh, and has the potential to make structural optimization of the mesh series products, which is suitable for practical application and promotion.