Wing design is a critical factor in the aerodynamic performance of flapping-wing(FW)robots.Inspired by the natural wing structures of insects,bats,and birds,we explored how bio-mimetic wing vein morphologies,combined ...Wing design is a critical factor in the aerodynamic performance of flapping-wing(FW)robots.Inspired by the natural wing structures of insects,bats,and birds,we explored how bio-mimetic wing vein morphologies,combined with a bio-inspired double wing clap-and-fling mechanism,affect thrust generation.This study focused on increasing vertical force and payload capacity.Through systematic experimentation with various vein configurations and structural designs,we developed innovative wings optimized for thrust production.Comprehensive tests were conducted to measure aerodynamic forces,power consumption,and wing kinematics across a range of flapping frequencies.Additionally,wings with different aspect ratios,a key factor in wing design,were fabricated and extensively evaluated.The study also examined the role of bio-inspired vein layouts on wing flexibility,a critical component in improving flight efficiency.Our findings demonstrate that the newly developed wing design led to a 20%increase in thrust,achieving up to 30 g-force(gf).This research sheds light on the clap-and-fling effect and establishes a promising framework for bio-inspired wing design,offering significant improvements in both performance and payload capacity for FW robots.展开更多
The core components of an aircraft and the source of its lift are its wings,but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired.Here,to inv...The core components of an aircraft and the source of its lift are its wings,but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired.Here,to investigate how this process influences the aerodynamic parameters of aircraft wings,the k-ωshearstress-transport turbulence model and the nested dynamic grid technique are used to analyze numerically the transient process of the muzzle jet of a 30-mm small-caliber aircraft gun in highaltitude(10 km)flight with an incoming Mach number of Ma=0.8.For comparison,two other models are established,one with no projectile and the other with no wing.The results indicate that when the aircraft gun is fired,the muzzle jet acts on the wing,creating a pressure field thereon.The uneven distribution of high pressure greatly reduces the lift of the aircraft,causing oscillations in its drag and disrupting its dynamic balance,thereby affecting its flight speed and attitude.Meanwhile,the muzzle jet is obstructed by the wing,and its flow field is distorted and deformed,developing upward toward the wing.Because of the influence of the incoming flow,the shockwave front of the projectile changes from a smooth spherical shape to an irregular one,and the motion parameters of the projectile are also greatly affected by oscillations.The present results provide an important theoretical basis for how the guns of fighter aircraft influence the aerodynamic performance of the wings.展开更多
Hypersonic morphing vehicle(HMV)can reconfigure aerodynamic geometries in real time,adapting to diverse needs like multi-mission profiles and wide-speed-range flight,spanwise morphing and sweep angle variation are rep...Hypersonic morphing vehicle(HMV)can reconfigure aerodynamic geometries in real time,adapting to diverse needs like multi-mission profiles and wide-speed-range flight,spanwise morphing and sweep angle variation are representative large-scale wing reconfiguration modes.To meet the HMV's need for an increased lift and a lift to drag ratio during hypersonic maneuverability and cruise or reentry equilibrium glide,this paper proposes an innovative single-DOF coupled morphing-wing system.We then systematically analyze its open-loop kinematics and closed-loop connectivity constraints,and the proposed system integrates three functional modules:the preset locking/release mechanism,the coupled morphing-wing mechanism,and the integrated wing locking with active stiffness control mechanism.Experimental validation confirms stable,continuous morphing under simulated aerodynamic loads.The experimental results indicate:(i)SMA actuators exhibit response times ranging from 18 s to 160 s,providing sufficient force output for wing unlocking;(ii)The integrated wing locking with active stiffness control mechanism effectively secures wing positions while eliminating airframe clearance via SMA actuation,improving the first-order natural frequency by more than 17%;(iii)The distributed aerodynamic loading system enables precise multi-stage follow-up loading during morphing,with the coupled morphing wing maintaining stable,continuous operation under 0-3500 N normal loads and 110-140 N axial force.The proposed single-DOF coupled morphing mechanism not only simplifies and improves structural efficiency but also demonstrates superior performance in locking control,stiffness enhancement,and aerodynamic responsiveness.This establishes a foundational framework for the design of future intelligent morphing configurations and the implementation of flight control systems.展开更多
Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or ...Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or attitude instability,seriously compromising mission reliability.To address this engineering challenge,this paper proposes a multi-point low-impact locking/release mechanism based on the mobility model and energy conversion strategy.Through establishing a DOF constraint framework system,this paper systematically analyzes the energy transfer and conversion characteristics during the wing separation process,reveals the generation mechanism of impact loads,and conducts research on low-impact design based on energy conversion strategy.Building on this foundation,a single-point locking/release mechanism employing parallel trapezoidal key shaft structure was designed,which increases frictional contact time and reduces the energy release rate,thereby achieving low-impact characteristics.The mechanism's performance was validated through physical prototype development and systematic functional testing(including unlocking force,synchronization,and impact tests).Experimental results demonstrate:(1)Under 14 kN preload condition,the maximum unlocking force was only 92.54 N,showing a linear relationship with preload that satisfies the"strong-connection/weak-unlock"design requirement;(2)Wing separation was completed within 46 ms,with synchronization time difference among three separation mechanisms stably controlled within 12-14 ms,proving rapid and reliable operation;(3)The unlocking impact acceleration ranged between 26 and 73 g,below the 100 g design limit,confirming the effectiveness of the energy conversion strategy.The proposed low-impact locking/release mechanism design method based on energy conversion strategy resolves the traditional challenges of high impact and synchronization deficiencies.The synergistic optimization mechanism of"structural load reduction and performance improvement"provides a highly reliable technical solution for wing separable mechanisms while offering novel design insights for wing connection/separation systems engineering.展开更多
High-aspect-ratio aircraft are widely used in military and civilian fields,such as reconnaissance,surveillance,and attacks,due to their high lift-to-drag ratio,strong payload capability,significant endurance effect,an...High-aspect-ratio aircraft are widely used in military and civilian fields,such as reconnaissance,surveillance,and attacks,due to their high lift-to-drag ratio,strong payload capability,significant endurance effect,and good stealth performance.However,compared to conventional aircraft,high-aspect-ratio aircraft are more susceptible to gust disturbances during flight.In response to this phenomenon,a full-scale dynamic model of a high-aspect-ratio unmanned aerial vehicle was developed.Considering the coupling among control surfaces,structural forces,and aerodynamic forces,along with sensor,actuator,and delay effects,an H_(∞)control law was designed using the principle of singular value energy flow reduction and weighted function,with a PID(Proportional-Integral-Derivative)control law for comparison.The two controllers were then subjected to pulse-response and jury stability tests.Finally,wind tunnel tests were conducted to investigate the gust alleviation principle,in which gust disturbances were generated using gust generators and control surface self-excitation.The results present that the average wing root bending moment and wing tip overload under the PID control law decrease by approximately 30%,while under the H_(∞)control law,both the average wing root bending moment and wing tip overload reduction rate exceed 50%,with peaks reaching 60%.This validates the feasibility and efficiency of the designed H_(∞)controller.展开更多
The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction...The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.展开更多
This paper investigates the influence of the spanwise-distributed trailing-edge camber morphing on the dynamic stall characteristics of a finite-span wing at Re=2×10^(5).The mathematical model of the spanwise-dis...This paper investigates the influence of the spanwise-distributed trailing-edge camber morphing on the dynamic stall characteristics of a finite-span wing at Re=2×10^(5).The mathematical model of the spanwise-distributed trailing-edge camber morphing is established based on Chebyshev polynomials,and the deformed wing surface is modeled by a spline surface according to the rib's morphing in the chordwise direction.The Computational Fluid Dynamics(CFD)method is adopted to obtain flow-field results and aerodynamic forces.The SST-γmodel is introduced and the overset mesh technique is adopted.The numerical results show that the spanwisedistributed trailing-edge morphing obviously changes the aerodynamic and energy transfer characteristics of the dynamic stall.Especially when the phase difference between the trailing-edge motion and the wing pitch is-π/2,the interaction between the three-dimensional(3-D)Leading-Edge Vortex(LEV)and Trailing-Edge Vortex(TEV)is strengthened,and the work done by the aerodynamic force turns negative.This indicates that the trailing-edge deformation has the potential to suppress the oscillation amplitude of stall flutter.We also found that as the trailing-edge camber morphing varies more complexly along the spanwise direction,the suppression effect decreases accordingly.展开更多
The optimization of wings typically relies on computationally intensive high-fidelity simulations,which restrict the quick exploration of design spaces.To address this problem,this paper introduces a methodology dedic...The optimization of wings typically relies on computationally intensive high-fidelity simulations,which restrict the quick exploration of design spaces.To address this problem,this paper introduces a methodology dedicated to optimizing box wing configurations using low-fidelity data driven machine learning approach.This technique showcases its practicality through the utilization of a tailored low-fidelity machine learning technique,specifically designed for early-stage wing configuration.By employing surrogate model trained on small dataset derived from low-fidelity simulations,our method aims to predict outputs within an acceptable range.This strategy significantly mitigates computational costs and expedites the design exploration process.The methodology's validation relies on its successful application in optimizing the box wing of PARSIFAL,serving as a benchmark,while the primary focus remains on optimizing the newly designed box wing by Bionica.Applying this method to the Bionica configuration led to a notable 14%improvement in overall aerodynamic effciency.Furthermore,all the optimized results obtained from machine learning model undergo rigorous assessments through the high-fidelity RANS analysis for confirmation.This methodology introduces innovative approach that aims to streamline computational processes,potentially reducing the time and resources required compared to traditional optimization methods.展开更多
A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produc...A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produce lift and thrust for hovering and forward flight. Considerations are given to the motion of a rigid and thin bi-wing and quad-wing ornithopter in flapping and pitching motion with phase lag. Basic Unsteady Aerodynamic Approach incorporating salient features of viscous effect and leading-edge suction are utilized. Parametric study is carried out to reveal the aerodynamic characteristics of flapping bi- and quad-wing ornithopter flight characteristics and for comparative analysis with various selected simple models in the literature, in an effort to develop a flapping bi- and quad-wing ornithopter models. In spite of their simplicity, results obtained for both models are able to reveal the mechanism of lift and thrust, and compare well with other work.展开更多
The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeogr...The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeographic studies(Wagner and Liebherr 1992;Peeters and Ito 2001;Helms 2018).展开更多
The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the vari...The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the variable drooping leading edge is proposed and extended to a single-aisle commercial aircraft with the swept wing.The outer-wing and full-spanwise drooping leading edge configurations are set up to distinguish the effect of different ice tolerant strategies.The Reynolds-averaged Navier-Stokes results reveal that the stall angle of attack is delayed by 25.0%,and the maximum lift coefficient is increased by 23.3%with the full-spanwise drooping in the presence of horn-shaped ice on the wing.This improvement is primarily driven by the recovery of leading-edge suction.With the formulation of the improved delayed detached eddy simulation,the structures and the behaviors of the separated flow near the stall point are analyzed via the comparison before and after drooping the leading edge in full-spanwise.The results indicate that the suppression of the spatial development of the shedding shear layer promotes the closure of the separation bubble and mitigates the sweeping motion of the large-scale spanwise vortex.These integrated effects contribute to the enhancement of ice tolerance.展开更多
Avian wings are central to their remarkable flight ability and diverse life history strategies,including behaviors such as fighting and mating.These multifaceted functions are intricately tied to wing shape,which vari...Avian wings are central to their remarkable flight ability and diverse life history strategies,including behaviors such as fighting and mating.These multifaceted functions are intricately tied to wing shape,which varies significantly across species because of the complex interplay of evolutionary and ecological pressures.Many indices have been developed to quantify wing characteristics to facilitate the study and comparison of avian wing morphology across species.This study provides a comprehensive overview of existing quantitative methods for analyzing avian wing shapes.We then constructed a new quantification framework through the beta distribution,which can generate indices reflecting the shape of avian wings(center,dispersion,skewness,and kurtosis).Next,we used the flight feathers of 613 bird species to perform different quantitative analyses and explore the relationships between various wing shape quantification methods and life history traits,which serve as proxies for the selective forces shaping wing morphology.We find that the wing shape indices are more strongly associated with ecological variables than with morphological variables,especially for migration,habitat and territoriality.This research guides the selection of appropriate methods for wing shape analysis,contributing to a deeper understanding of avian morphology and its evolutionary drivers.展开更多
This paper introduces an innovative approach to the deployment of folding wings on cruise missiles,aiming to overcome the issues associated with explosive devices.The proposed solution involves employing NiTi shape me...This paper introduces an innovative approach to the deployment of folding wings on cruise missiles,aiming to overcome the issues associated with explosive devices.The proposed solution involves employing NiTi shape memory wires for a nonexplosive self-deploying wing mechanism.The fundamental concept of the design revolves around the utilization of NiTi wires,which contract upon electric heating.This contraction action severs the shear pin,consequently releasing the folded wings.The operational performance of the NiTi wire is thoroughly examined through a series of electro-thermo-mechanical tests,offering valuable insights for selecting the appropriate wire material.Moreover,the mechanical dynamics involved in the self-deploying process are elucidated through finite element simulations.The simulations highlight that the thermally-induced phase transformation within the NiTi wires generates substantial actuation forces,exceeding 700 N,and strokes of over 6 mm.These forces are deemed sufficient for breaking the aluminum shear pin and effecting wing deployment.The proposed mechanism’s practical viability is substantiated through prototype tests,which conclusively establish the superiority of the nonexplosive self-deploying wing mechanism when compared to conventional methods.The experimental outcomes underscore the mechanism’s capability to markedly reduce overload stress while remaining compliant with the designated requirements and constraints.展开更多
Aeroelastic control is a critical technique for high-aspect-ratio flexible wings.A novel aeroelastic control method is introduced,utilizing the internal Moving Mass Control(MMC)technique,which demonstrates the potenti...Aeroelastic control is a critical technique for high-aspect-ratio flexible wings.A novel aeroelastic control method is introduced,utilizing the internal Moving Mass Control(MMC)technique,which demonstrates the potential to fulfill hybrid control demands without incurring a drag penalty.Dynamic equations for a flexible wing equipped with a spanwise moving mass under unsteady aerodynamic loading are derived using mass position as the input variable.Controloriented analyses indicate that intrinsic structural frequencies,flutter characteristics,and gust response can be actively modified by varying the spanwise and chordwise positions of the mass element.Among these,the chordwise position exerts a more significant impact on the structural modes and flutter speed of the wing.A hybrid aeroelastic control system,incorporating motion planning and control law,is proposed to evaluate real-time performance in Active Flutter Suppression(AFS)and Gust Load Alleviation(GLA).Control outcomes suggest that,with a mass ratio of 1/16 and a half-chord installation area for the guide rail,flutter speed increases by about 10%.Additionally,excitation amplitudes across different gust frequencies are substantially mitigated,achieving a maximum reduction of vibration amplitude by about 73%.These findings offer a comprehensive understanding of the MMC technique and its application to flexible aircraft.展开更多
This paper presents a novel modelling method to study the thrust generation mechanism of biplane flapping wings made of thin and highly deformable membrane.Based on the principle of strain energy equivalence,the membr...This paper presents a novel modelling method to study the thrust generation mechanism of biplane flapping wings made of thin and highly deformable membrane.Based on the principle of strain energy equivalence,the membrane structures were modelled by mass-spring systems.The aerodynamic loads were calculated by a simplified quasi-steady aerodynamic model with consideration of the clap-and-fling mechanism.The impact force was introduced into the system when two wing surfaces were in contact.For wing-dynamics simulation problems,convergence analyses were conducted to obtain suitable mesh resolution.To validate the present modelling method,the predicted thrust and required power of a biplane flapping-wing air vehicle were compared with the experimental data.The effect of the forward speed was also analyzed in this paper.It was shown that as the forward speed increases the thrust production efficiency becomes lower together with smaller wing deformation.展开更多
Superhydrophobic/superhydrophilic antifouling materials are widely used to solve the severe water pollution and bio-adhesion of marine equipment.However,conventional antifouling materials rely on the static superwetta...Superhydrophobic/superhydrophilic antifouling materials are widely used to solve the severe water pollution and bio-adhesion of marine equipment.However,conventional antifouling materials rely on the static superwettability of surfaces,which suffer from poorly sustained antifouling effects.Inspired by the unique dynamic antifouling strategies of Calliphora Vicina wing surface based on the hydrophobic micro-cilia arrays,a Biomimetic Magnetic-Responsive Antifouling Surface(BMRAS)is designed and fabricated using a method combining UV lithography and an inverse molding.The BMRAS is coated by high-aspect-ratio micro-cilia,which are filled with synthesized magnetic Fe3O4 nanoparticles.The bioinspired hydrophobic micro-cilia arrays endow the BMRAS with excellent intrinsic superhydrophobicity,benefiting from the high-aspect-ratio feature and roughness effect.Remarkably,the static contact angle is more than 156.9±1.6°and the rolling angle is less than 2.3±0.3°.The synthesized magnetic nanomaterials play a key role in implementing dynamic antifouling strategies.On the one hand,the surface tension can be adjusted as required under magnetically controlled oscillations.On the other hand,the doping of magnetic nanomaterials can enhance mechanical properties and reduce capillary force-induced aggregation of high-aspect-ratio micro-cilia.The antifouling tests demonstrate that the chemically modified micro-cilia can effectively expel gravels under the stimulation of an external magnetic field and enable the BMRAS to achieve dynamic self-cleaning.Specifically,0.17 g gravel distributed on BMRAS can be completely cleaned up within 0.296 s,which improved by 14.2%compared with the flat materials.This work provides a brief and effective strategy for designing dynamic antifouling surfaces with excellent physicochemical durability and great potential value in the applications of marine fouling.展开更多
The spatial constraints of aircraft have accelerated the development of multi-wing deployable mechanisms.These systems enable the rapid,sub-second deployment of multiple folding wings,which generate high-energy impact...The spatial constraints of aircraft have accelerated the development of multi-wing deployable mechanisms.These systems enable the rapid,sub-second deployment of multiple folding wings,which generate high-energy impacts upon locking-resulting in oscillations that can adversely affect aerodynamic performance.Despite their importance,the transient dynamic characteristics during deployment and locking remain insufficiently explored.This study presents an integrated dynamic model for a single-actuator,multi-wing deployable mechanism that accounts for joint clearances,component elasticity,and locking collisions.This model is used to analyze the influence of transient driving on the motion errors of multiple folding wings,the locking oscillation amplitude,and the complete stabilization time.Results indicate that as the driving force and transient deployment speed increase,all dynamic performance characteristics are notably affected.Specifically,raising the transient driving force from 3000 to 7000 N leads to a maximum increase of 60.8%in oscillation amplitude and 78.4%in stabilization time.By comparing the results of the prototype experiment with the theoretical model,it is found that the errors of the maximum locking oscillation amplitude and the complete stabilization time for the three groups of folding wings are all within the acceptable range,which verifies the theoretical model.These findings advance the theoretical understanding of transient deployment dynamics and locking oscillations in high-speed deployable mechanisms.展开更多
基金Nguyen Tat Thanh University,Ho Chi Minh City,Vietnam for supporting this study。
文摘Wing design is a critical factor in the aerodynamic performance of flapping-wing(FW)robots.Inspired by the natural wing structures of insects,bats,and birds,we explored how bio-mimetic wing vein morphologies,combined with a bio-inspired double wing clap-and-fling mechanism,affect thrust generation.This study focused on increasing vertical force and payload capacity.Through systematic experimentation with various vein configurations and structural designs,we developed innovative wings optimized for thrust production.Comprehensive tests were conducted to measure aerodynamic forces,power consumption,and wing kinematics across a range of flapping frequencies.Additionally,wings with different aspect ratios,a key factor in wing design,were fabricated and extensively evaluated.The study also examined the role of bio-inspired vein layouts on wing flexibility,a critical component in improving flight efficiency.Our findings demonstrate that the newly developed wing design led to a 20%increase in thrust,achieving up to 30 g-force(gf).This research sheds light on the clap-and-fling effect and establishes a promising framework for bio-inspired wing design,offering significant improvements in both performance and payload capacity for FW robots.
基金supported by the National Natural Science Foundation of China(Grant No.12402268)the Fundamental Research Funds for the Central Universities(Grant No.30925010410)。
文摘The core components of an aircraft and the source of its lift are its wings,but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired.Here,to investigate how this process influences the aerodynamic parameters of aircraft wings,the k-ωshearstress-transport turbulence model and the nested dynamic grid technique are used to analyze numerically the transient process of the muzzle jet of a 30-mm small-caliber aircraft gun in highaltitude(10 km)flight with an incoming Mach number of Ma=0.8.For comparison,two other models are established,one with no projectile and the other with no wing.The results indicate that when the aircraft gun is fired,the muzzle jet acts on the wing,creating a pressure field thereon.The uneven distribution of high pressure greatly reduces the lift of the aircraft,causing oscillations in its drag and disrupting its dynamic balance,thereby affecting its flight speed and attitude.Meanwhile,the muzzle jet is obstructed by the wing,and its flow field is distorted and deformed,developing upward toward the wing.Because of the influence of the incoming flow,the shockwave front of the projectile changes from a smooth spherical shape to an irregular one,and the motion parameters of the projectile are also greatly affected by oscillations.The present results provide an important theoretical basis for how the guns of fighter aircraft influence the aerodynamic performance of the wings.
基金supported by the National Natural Science Foundation of China(Grant No.52405257)the China Postdoctoral Science Foundation(Grant No.2024M764201).
文摘Hypersonic morphing vehicle(HMV)can reconfigure aerodynamic geometries in real time,adapting to diverse needs like multi-mission profiles and wide-speed-range flight,spanwise morphing and sweep angle variation are representative large-scale wing reconfiguration modes.To meet the HMV's need for an increased lift and a lift to drag ratio during hypersonic maneuverability and cruise or reentry equilibrium glide,this paper proposes an innovative single-DOF coupled morphing-wing system.We then systematically analyze its open-loop kinematics and closed-loop connectivity constraints,and the proposed system integrates three functional modules:the preset locking/release mechanism,the coupled morphing-wing mechanism,and the integrated wing locking with active stiffness control mechanism.Experimental validation confirms stable,continuous morphing under simulated aerodynamic loads.The experimental results indicate:(i)SMA actuators exhibit response times ranging from 18 s to 160 s,providing sufficient force output for wing unlocking;(ii)The integrated wing locking with active stiffness control mechanism effectively secures wing positions while eliminating airframe clearance via SMA actuation,improving the first-order natural frequency by more than 17%;(iii)The distributed aerodynamic loading system enables precise multi-stage follow-up loading during morphing,with the coupled morphing wing maintaining stable,continuous operation under 0-3500 N normal loads and 110-140 N axial force.The proposed single-DOF coupled morphing mechanism not only simplifies and improves structural efficiency but also demonstrates superior performance in locking control,stiffness enhancement,and aerodynamic responsiveness.This establishes a foundational framework for the design of future intelligent morphing configurations and the implementation of flight control systems.
文摘Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or attitude instability,seriously compromising mission reliability.To address this engineering challenge,this paper proposes a multi-point low-impact locking/release mechanism based on the mobility model and energy conversion strategy.Through establishing a DOF constraint framework system,this paper systematically analyzes the energy transfer and conversion characteristics during the wing separation process,reveals the generation mechanism of impact loads,and conducts research on low-impact design based on energy conversion strategy.Building on this foundation,a single-point locking/release mechanism employing parallel trapezoidal key shaft structure was designed,which increases frictional contact time and reduces the energy release rate,thereby achieving low-impact characteristics.The mechanism's performance was validated through physical prototype development and systematic functional testing(including unlocking force,synchronization,and impact tests).Experimental results demonstrate:(1)Under 14 kN preload condition,the maximum unlocking force was only 92.54 N,showing a linear relationship with preload that satisfies the"strong-connection/weak-unlock"design requirement;(2)Wing separation was completed within 46 ms,with synchronization time difference among three separation mechanisms stably controlled within 12-14 ms,proving rapid and reliable operation;(3)The unlocking impact acceleration ranged between 26 and 73 g,below the 100 g design limit,confirming the effectiveness of the energy conversion strategy.The proposed low-impact locking/release mechanism design method based on energy conversion strategy resolves the traditional challenges of high impact and synchronization deficiencies.The synergistic optimization mechanism of"structural load reduction and performance improvement"provides a highly reliable technical solution for wing separable mechanisms while offering novel design insights for wing connection/separation systems engineering.
基金supported by the National Natural Science Foundation of China(Nos.12272104,U22B2013).
文摘High-aspect-ratio aircraft are widely used in military and civilian fields,such as reconnaissance,surveillance,and attacks,due to their high lift-to-drag ratio,strong payload capability,significant endurance effect,and good stealth performance.However,compared to conventional aircraft,high-aspect-ratio aircraft are more susceptible to gust disturbances during flight.In response to this phenomenon,a full-scale dynamic model of a high-aspect-ratio unmanned aerial vehicle was developed.Considering the coupling among control surfaces,structural forces,and aerodynamic forces,along with sensor,actuator,and delay effects,an H_(∞)control law was designed using the principle of singular value energy flow reduction and weighted function,with a PID(Proportional-Integral-Derivative)control law for comparison.The two controllers were then subjected to pulse-response and jury stability tests.Finally,wind tunnel tests were conducted to investigate the gust alleviation principle,in which gust disturbances were generated using gust generators and control surface self-excitation.The results present that the average wing root bending moment and wing tip overload under the PID control law decrease by approximately 30%,while under the H_(∞)control law,both the average wing root bending moment and wing tip overload reduction rate exceed 50%,with peaks reaching 60%.This validates the feasibility and efficiency of the designed H_(∞)controller.
基金supported by the Istanbul Technical University Office of Scientific Research Projects(ITUBAPSIS),under grant MYL-2022-43776。
文摘The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.
基金co-supported by the National Natural Science Foundation of China(No.12472332)。
文摘This paper investigates the influence of the spanwise-distributed trailing-edge camber morphing on the dynamic stall characteristics of a finite-span wing at Re=2×10^(5).The mathematical model of the spanwise-distributed trailing-edge camber morphing is established based on Chebyshev polynomials,and the deformed wing surface is modeled by a spline surface according to the rib's morphing in the chordwise direction.The Computational Fluid Dynamics(CFD)method is adopted to obtain flow-field results and aerodynamic forces.The SST-γmodel is introduced and the overset mesh technique is adopted.The numerical results show that the spanwisedistributed trailing-edge morphing obviously changes the aerodynamic and energy transfer characteristics of the dynamic stall.Especially when the phase difference between the trailing-edge motion and the wing pitch is-π/2,the interaction between the three-dimensional(3-D)Leading-Edge Vortex(LEV)and Trailing-Edge Vortex(TEV)is strengthened,and the work done by the aerodynamic force turns negative.This indicates that the trailing-edge deformation has the potential to suppress the oscillation amplitude of stall flutter.We also found that as the trailing-edge camber morphing varies more complexly along the spanwise direction,the suppression effect decreases accordingly.
基金The funding for this publication was provided by Johannes Kepler University(JKU),Linz.Special thanks to Prof.Zongmin DENG from Beihang University for his invaluable guidance,insightful feedback,and constructive criticism,which greatly enhanced the quality of this manuscript.We extend our heartfelt gratitude to the PARSIFAL team for providing the supporting materials,which inspired this study.
文摘The optimization of wings typically relies on computationally intensive high-fidelity simulations,which restrict the quick exploration of design spaces.To address this problem,this paper introduces a methodology dedicated to optimizing box wing configurations using low-fidelity data driven machine learning approach.This technique showcases its practicality through the utilization of a tailored low-fidelity machine learning technique,specifically designed for early-stage wing configuration.By employing surrogate model trained on small dataset derived from low-fidelity simulations,our method aims to predict outputs within an acceptable range.This strategy significantly mitigates computational costs and expedites the design exploration process.The methodology's validation relies on its successful application in optimizing the box wing of PARSIFAL,serving as a benchmark,while the primary focus remains on optimizing the newly designed box wing by Bionica.Applying this method to the Bionica configuration led to a notable 14%improvement in overall aerodynamic effciency.Furthermore,all the optimized results obtained from machine learning model undergo rigorous assessments through the high-fidelity RANS analysis for confirmation.This methodology introduces innovative approach that aims to streamline computational processes,potentially reducing the time and resources required compared to traditional optimization methods.
文摘A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produce lift and thrust for hovering and forward flight. Considerations are given to the motion of a rigid and thin bi-wing and quad-wing ornithopter in flapping and pitching motion with phase lag. Basic Unsteady Aerodynamic Approach incorporating salient features of viscous effect and leading-edge suction are utilized. Parametric study is carried out to reveal the aerodynamic characteristics of flapping bi- and quad-wing ornithopter flight characteristics and for comparative analysis with various selected simple models in the literature, in an effort to develop a flapping bi- and quad-wing ornithopter models. In spite of their simplicity, results obtained for both models are able to reveal the mechanism of lift and thrust, and compare well with other work.
基金funded by the“Departments of Excellence”program of the Italian Ministry for University and Research(MIUR,2018-2022 and MUR,2023-2027).
文摘The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeographic studies(Wagner and Liebherr 1992;Peeters and Ito 2001;Helms 2018).
基金co-supported by the National Natural Science Foundation of China(Nos.12302300,12272312,12372288 and 12388101)the Open Fund of Key Laboratory of Icing and Anti/De-icing,China(No.IADL20220413)the 1-0 Major Engineering Science Problem Project of Northwestern Polytechnical University(No.G2024KY0613)。
文摘The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the variable drooping leading edge is proposed and extended to a single-aisle commercial aircraft with the swept wing.The outer-wing and full-spanwise drooping leading edge configurations are set up to distinguish the effect of different ice tolerant strategies.The Reynolds-averaged Navier-Stokes results reveal that the stall angle of attack is delayed by 25.0%,and the maximum lift coefficient is increased by 23.3%with the full-spanwise drooping in the presence of horn-shaped ice on the wing.This improvement is primarily driven by the recovery of leading-edge suction.With the formulation of the improved delayed detached eddy simulation,the structures and the behaviors of the separated flow near the stall point are analyzed via the comparison before and after drooping the leading edge in full-spanwise.The results indicate that the suppression of the spatial development of the shedding shear layer promotes the closure of the separation bubble and mitigates the sweeping motion of the large-scale spanwise vortex.These integrated effects contribute to the enhancement of ice tolerance.
基金supported by the National Natural Science Foundation of China(No.32170491)the Scientific Research Team Project of the College of Life Sciences,Beijing Normal University in 2024。
文摘Avian wings are central to their remarkable flight ability and diverse life history strategies,including behaviors such as fighting and mating.These multifaceted functions are intricately tied to wing shape,which varies significantly across species because of the complex interplay of evolutionary and ecological pressures.Many indices have been developed to quantify wing characteristics to facilitate the study and comparison of avian wing morphology across species.This study provides a comprehensive overview of existing quantitative methods for analyzing avian wing shapes.We then constructed a new quantification framework through the beta distribution,which can generate indices reflecting the shape of avian wings(center,dispersion,skewness,and kurtosis).Next,we used the flight feathers of 613 bird species to perform different quantitative analyses and explore the relationships between various wing shape quantification methods and life history traits,which serve as proxies for the selective forces shaping wing morphology.We find that the wing shape indices are more strongly associated with ecological variables than with morphological variables,especially for migration,habitat and territoriality.This research guides the selection of appropriate methods for wing shape analysis,contributing to a deeper understanding of avian morphology and its evolutionary drivers.
基金Supported by National Natural Science Foundation of China(Grant No.12372156).
文摘This paper introduces an innovative approach to the deployment of folding wings on cruise missiles,aiming to overcome the issues associated with explosive devices.The proposed solution involves employing NiTi shape memory wires for a nonexplosive self-deploying wing mechanism.The fundamental concept of the design revolves around the utilization of NiTi wires,which contract upon electric heating.This contraction action severs the shear pin,consequently releasing the folded wings.The operational performance of the NiTi wire is thoroughly examined through a series of electro-thermo-mechanical tests,offering valuable insights for selecting the appropriate wire material.Moreover,the mechanical dynamics involved in the self-deploying process are elucidated through finite element simulations.The simulations highlight that the thermally-induced phase transformation within the NiTi wires generates substantial actuation forces,exceeding 700 N,and strokes of over 6 mm.These forces are deemed sufficient for breaking the aluminum shear pin and effecting wing deployment.The proposed mechanism’s practical viability is substantiated through prototype tests,which conclusively establish the superiority of the nonexplosive self-deploying wing mechanism when compared to conventional methods.The experimental outcomes underscore the mechanism’s capability to markedly reduce overload stress while remaining compliant with the designated requirements and constraints.
基金supported by the National Natural Science Foundation of China(No.12102096)the Guangdong Basic and Applied Basic Research Foundation,China(No.2022A1515011885)the Research Fund of National Key Laboratory of Aerospace Physics in Fluids,China(No.2024-APF-KFQMJJ-08)。
文摘Aeroelastic control is a critical technique for high-aspect-ratio flexible wings.A novel aeroelastic control method is introduced,utilizing the internal Moving Mass Control(MMC)technique,which demonstrates the potential to fulfill hybrid control demands without incurring a drag penalty.Dynamic equations for a flexible wing equipped with a spanwise moving mass under unsteady aerodynamic loading are derived using mass position as the input variable.Controloriented analyses indicate that intrinsic structural frequencies,flutter characteristics,and gust response can be actively modified by varying the spanwise and chordwise positions of the mass element.Among these,the chordwise position exerts a more significant impact on the structural modes and flutter speed of the wing.A hybrid aeroelastic control system,incorporating motion planning and control law,is proposed to evaluate real-time performance in Active Flutter Suppression(AFS)and Gust Load Alleviation(GLA).Control outcomes suggest that,with a mass ratio of 1/16 and a half-chord installation area for the guide rail,flutter speed increases by about 10%.Additionally,excitation amplitudes across different gust frequencies are substantially mitigated,achieving a maximum reduction of vibration amplitude by about 73%.These findings offer a comprehensive understanding of the MMC technique and its application to flexible aircraft.
基金funded by Vietnam National Foundation for Science and Technology Development(NAFOSTED)(Grant No.107.01-2021.39).
文摘This paper presents a novel modelling method to study the thrust generation mechanism of biplane flapping wings made of thin and highly deformable membrane.Based on the principle of strain energy equivalence,the membrane structures were modelled by mass-spring systems.The aerodynamic loads were calculated by a simplified quasi-steady aerodynamic model with consideration of the clap-and-fling mechanism.The impact force was introduced into the system when two wing surfaces were in contact.For wing-dynamics simulation problems,convergence analyses were conducted to obtain suitable mesh resolution.To validate the present modelling method,the predicted thrust and required power of a biplane flapping-wing air vehicle were compared with the experimental data.The effect of the forward speed was also analyzed in this paper.It was shown that as the forward speed increases the thrust production efficiency becomes lower together with smaller wing deformation.
基金supported by the National Key Research and Development Program of China(2023YFB4605700)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)+4 种基金the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(No.52222509)the Natural Science Foundation of Jilin Province(No.20220101220JC)the Defense Industrial Technology Development Program(JCKY2023130C001)Changbai Talents Plan of Jilin Province“Fundamental Research Funds for the Central Universities”.
文摘Superhydrophobic/superhydrophilic antifouling materials are widely used to solve the severe water pollution and bio-adhesion of marine equipment.However,conventional antifouling materials rely on the static superwettability of surfaces,which suffer from poorly sustained antifouling effects.Inspired by the unique dynamic antifouling strategies of Calliphora Vicina wing surface based on the hydrophobic micro-cilia arrays,a Biomimetic Magnetic-Responsive Antifouling Surface(BMRAS)is designed and fabricated using a method combining UV lithography and an inverse molding.The BMRAS is coated by high-aspect-ratio micro-cilia,which are filled with synthesized magnetic Fe3O4 nanoparticles.The bioinspired hydrophobic micro-cilia arrays endow the BMRAS with excellent intrinsic superhydrophobicity,benefiting from the high-aspect-ratio feature and roughness effect.Remarkably,the static contact angle is more than 156.9±1.6°and the rolling angle is less than 2.3±0.3°.The synthesized magnetic nanomaterials play a key role in implementing dynamic antifouling strategies.On the one hand,the surface tension can be adjusted as required under magnetically controlled oscillations.On the other hand,the doping of magnetic nanomaterials can enhance mechanical properties and reduce capillary force-induced aggregation of high-aspect-ratio micro-cilia.The antifouling tests demonstrate that the chemically modified micro-cilia can effectively expel gravels under the stimulation of an external magnetic field and enable the BMRAS to achieve dynamic self-cleaning.Specifically,0.17 g gravel distributed on BMRAS can be completely cleaned up within 0.296 s,which improved by 14.2%compared with the flat materials.This work provides a brief and effective strategy for designing dynamic antifouling surfaces with excellent physicochemical durability and great potential value in the applications of marine fouling.
基金Supported by National Natural Science Foundation of China(Grant Nos.52192634,92471202,52105013,U2341237,T2388101).
文摘The spatial constraints of aircraft have accelerated the development of multi-wing deployable mechanisms.These systems enable the rapid,sub-second deployment of multiple folding wings,which generate high-energy impacts upon locking-resulting in oscillations that can adversely affect aerodynamic performance.Despite their importance,the transient dynamic characteristics during deployment and locking remain insufficiently explored.This study presents an integrated dynamic model for a single-actuator,multi-wing deployable mechanism that accounts for joint clearances,component elasticity,and locking collisions.This model is used to analyze the influence of transient driving on the motion errors of multiple folding wings,the locking oscillation amplitude,and the complete stabilization time.Results indicate that as the driving force and transient deployment speed increase,all dynamic performance characteristics are notably affected.Specifically,raising the transient driving force from 3000 to 7000 N leads to a maximum increase of 60.8%in oscillation amplitude and 78.4%in stabilization time.By comparing the results of the prototype experiment with the theoretical model,it is found that the errors of the maximum locking oscillation amplitude and the complete stabilization time for the three groups of folding wings are all within the acceptable range,which verifies the theoretical model.These findings advance the theoretical understanding of transient deployment dynamics and locking oscillations in high-speed deployable mechanisms.
