In order to analyze the effects of forward-swept angle and skin ply-orientation on the static and dynamic aeroelastic characteristics, the aeroelastic modeling and calculation for high-aspect-ratio composite wings wit...In order to analyze the effects of forward-swept angle and skin ply-orientation on the static and dynamic aeroelastic characteristics, the aeroelastic modeling and calculation for high-aspect-ratio composite wings with different forward-swept angles and skin ply-orientation are performed. This paper presents the results of a design study aiming to optimize wings with typical forward-swept angles and skin ply-orientation in an aeroelastic way by using the genetic/sensitivity-based hybrid algorithm. Under the conditions of satiated multiple constraints including strength, displacements, divergence speeds and flutter speeds, the studies are carried out in a bid to minimize the structural weight of a wing with the lay-up thicknesses of wing components as design variabies. In addition, the effects of the power of spanwise variation function of lay-up thicknesses of skins and iugs on the optimized weights are also analyzed.展开更多
A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness （CUS） configuration ...A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness （CUS） configuration and circumferentially asymmetric stiffness （CAS） configuration, are investigated. The present structural modeling method is validated through ANSYS FEM software for the case of a composite box beam. Then, the case of a single-cell composite wing with NACA0012 airfoil shape is considered. To investigate the aeroelastic problem of high-aspect-ratio composite wings, the linear ONERA aerodynamic model is used to model the unsteady aerodynamic loads under the case of small angle of attack. Finally, flutter speeds of the high-aspect-ratio wing with various composite ply angles are determined by using U-g method.展开更多
The stall flutter characters of high-aspect-ratio composite wing are investigated, and the effects of structure geometric nonlinearity and stiffness couple created by composite anisotropy on them also are discussed. F...The stall flutter characters of high-aspect-ratio composite wing are investigated, and the effects of structure geometric nonlinearity and stiffness couple created by composite anisotropy on them also are discussed. Firstly, the high-aspect-ratio wing is modeled as a composite thin-walled closed section Euler beam whose displacement and rotation both could be of finite value, and the nonlinear dynamic equations is build up on it with all the effects of geometric nonlinearity, aerodynamic nonlinearity and anisotropy of material being considered. Then vibration equations are deduced through perturbing the dynamic equations at wing＇s equilibrium position, and coupled with unsteady stall aerodynamic model and ONERA model, to obtain the nonlinear stall flutter analysis equations of wing. Finally, the flutter stabilities with various wind speeds are determined by the harmonic balance method. With several exampies, the validity of the stall flutter model is proved, and the significant effects of geometric nonlinearity on the stall flutter various characters as wall as the effects of ply angle on the stall flutter speed and frequency also are discussed.展开更多
A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels wi...A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels with manifold structures. On the basis of multi-tool milling process, the structural design of the manifold side height, microchannel length, width, number, and interval were analyzed. The heat transfer performances of high-aspect-ratio microchannel heat exchangers with two different manifolds were investigated by experiments, and the influencing factors were analyzed. The results indicate that the magnitude of heat transfer area per unit volume dominates the heat transfer performances of plate-type micro heat exchanger, while the velocity distribution between microchannels has little effects on the heat transfer performances.展开更多
The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wing...The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wings.The sensitivity information of wing spanwise stiffness distribution with respect to the twist angle at wing tip,the vertical displacement at wing tip,and the flutter speed are obtained using a sensitivity method for both models.Then the relationship between stiffness distribution and aeroelastic performance is summarized to guide the design procedure.By using the genetic/sensitivity-based hybrid algorithm,an optimal solution satisfying the strength,aeroelastic and manufacturing constraints is obtained.It is found that the summarized guidance is well consistent with the optimal solution,thus providing a valuable design advice with efficiency.The study also shows that the aeroelastic-optimization-based global stiffness design procedure can obtain the optimal solution under multiple constraints with high efficiency and precision,thereby having a strong application value in engineering.展开更多
In order to get an effective solution of the in-flight wing deformation measurement for high-wing aircrafts with high-aspect-ratio,a method based on three-dimensional(3D)speckle correlation technique is proposed.First...In order to get an effective solution of the in-flight wing deformation measurement for high-wing aircrafts with high-aspect-ratio,a method based on three-dimensional(3D)speckle correlation technique is proposed.Firstly,an in-flight wing deformation measurement system with two sets of conjugate cameras is designed based on structural characteristics and test requirements of high-wing aircrafts with large-aspect-ratio.Secondly,the in-flight wing deformation measurement method based on 3D speckle correlation technique is introduced including three aspects:measuring system and wing datum calibration,speckle image matching and 3D reconstruction,and wing deformation analysis.Fi-nally,ground simulation test of dynamic deformation measurement of a scaled model wing and flight test of dynamic deformation measurement of a large transport wing are carried out.The test results show that the measuring accuracy of single point coordinate in ground simulation test is better than 0.1 mm/m,in the airborne vibration environment,the static single-point positioning accuracy is bet-ter than 5 mm,and the in-flight wing deformation measurement data is well received by the flight test engineers.This method can satisfy the requirements of stability,reliability,high precision,non-con-tact and full-field measurement for dynamic deformation measurement of aircraft wing with high-as-pect-ratio.展开更多
For the strong coupling among the channels of bank-to-turn （BTT） missile with high-aspect-ratio wing, an autopilot is designed with a two loop control structure robust autopilot design methods. By the inner loop des...For the strong coupling among the channels of bank-to-turn （BTT） missile with high-aspect-ratio wing, an autopilot is designed with a two loop control structure robust autopilot design methods. By the inner loop design, the question of pole-zero cancellation is solved, and the stabilization of structured uncertainty is achieved. Through the outer loop of H∞ controller design, the flying performance and robustness can be guaranteed. The nonlinear simulation results show that the autopilot designed has perfect time domain response, and can suppress bad influence of the inertial and kinematics couplings. It can make the missile fly stably in the large flying areas. The control is very effective.展开更多
Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in ...Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.展开更多
High-aspect-ratio structures with heights or depths significantly exceeding their lateral dimensions hold broad application potential across various fields.The production of these structures is challenging,requiring m...High-aspect-ratio structures with heights or depths significantly exceeding their lateral dimensions hold broad application potential across various fields.The production of these structures is challenging,requiring meticulous control over materials,scale,and precision.We introduce an economical and efficient approach for fabricating high-aspect-ratio nanostructures using a two-photon polymerization process.This approach achieves feature sizes of around 37 nm with an aspect ratio of 10:1 using commercial photoresists.Offering advantages over traditional techniques,our approach simplifies operation and enhances design flexibility,facilitating the creation of smaller,more complex,and high-aspect-ratio structures.The capabilities of this approach are demonstrated by producing arrays of three-dimensional microstructures that exhibit sub-micron scales,extensive periodicity,and pronounced aspect ratios.These developments open new possibilities for applications in biomedical,precision engineering,and optical microdevice manufacturing.展开更多
Fixed-wing long-endurance aircraft play an important role in many fields.However,to reduce drag,these aircraft often have an enormous aspect ratio and wingspan,leading to challenges such as high requirements for takeo...Fixed-wing long-endurance aircraft play an important role in many fields.However,to reduce drag,these aircraft often have an enormous aspect ratio and wingspan,leading to challenges such as high requirements for takeoff and landing sites and poor wind resistance.Morphing may be able to solve this problem,but conventional morphing aircraft often employ complex actuation mechanisms and actuators to drive the morphing process.The associated costs in terms of structural weight increase and space occupancy are prohibitively high.First,this article develops a high-aspect-ratio aircraft with aerodynamic-driven morphing and validates the rationality and feasibility of this concept through flight tests.Then,focusing on the RQ-4‘‘Global Hawk”as the design baseline,the article explores multidisciplinary overall design methods for the aircraft,analyzing the comprehensive impact of morphing on aerodynamic,structural,and flight control design.Finally,the article elaborates on the benefits and costs associated with aerodynamic-driven morphing.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
文摘In order to analyze the effects of forward-swept angle and skin ply-orientation on the static and dynamic aeroelastic characteristics, the aeroelastic modeling and calculation for high-aspect-ratio composite wings with different forward-swept angles and skin ply-orientation are performed. This paper presents the results of a design study aiming to optimize wings with typical forward-swept angles and skin ply-orientation in an aeroelastic way by using the genetic/sensitivity-based hybrid algorithm. Under the conditions of satiated multiple constraints including strength, displacements, divergence speeds and flutter speeds, the studies are carried out in a bid to minimize the structural weight of a wing with the lay-up thicknesses of wing components as design variabies. In addition, the effects of the power of spanwise variation function of lay-up thicknesses of skins and iugs on the optimized weights are also analyzed.
文摘A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness （CUS） configuration and circumferentially asymmetric stiffness （CAS） configuration, are investigated. The present structural modeling method is validated through ANSYS FEM software for the case of a composite box beam. Then, the case of a single-cell composite wing with NACA0012 airfoil shape is considered. To investigate the aeroelastic problem of high-aspect-ratio composite wings, the linear ONERA aerodynamic model is used to model the unsteady aerodynamic loads under the case of small angle of attack. Finally, flutter speeds of the high-aspect-ratio wing with various composite ply angles are determined by using U-g method.
文摘The stall flutter characters of high-aspect-ratio composite wing are investigated, and the effects of structure geometric nonlinearity and stiffness couple created by composite anisotropy on them also are discussed. Firstly, the high-aspect-ratio wing is modeled as a composite thin-walled closed section Euler beam whose displacement and rotation both could be of finite value, and the nonlinear dynamic equations is build up on it with all the effects of geometric nonlinearity, aerodynamic nonlinearity and anisotropy of material being considered. Then vibration equations are deduced through perturbing the dynamic equations at wing＇s equilibrium position, and coupled with unsteady stall aerodynamic model and ONERA model, to obtain the nonlinear stall flutter analysis equations of wing. Finally, the flutter stabilities with various wind speeds are determined by the harmonic balance method. With several exampies, the validity of the stall flutter model is proved, and the significant effects of geometric nonlinearity on the stall flutter various characters as wall as the effects of ply angle on the stall flutter speed and frequency also are discussed.
基金Projects(50675070 50805052) supported by the National Nature Science Foundation of China+1 种基金Projects(07118064 8451064101000320) supported by the Natural Science Foundation of Guangdong Province
文摘A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels with manifold structures. On the basis of multi-tool milling process, the structural design of the manifold side height, microchannel length, width, number, and interval were analyzed. The heat transfer performances of high-aspect-ratio microchannel heat exchangers with two different manifolds were investigated by experiments, and the influencing factors were analyzed. The results indicate that the magnitude of heat transfer area per unit volume dominates the heat transfer performances of plate-type micro heat exchanger, while the velocity distribution between microchannels has little effects on the heat transfer performances.
基金supported by the National Natural Science Foundation of China (Nos.11302011,11372023, 11172025)
文摘The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wings.The sensitivity information of wing spanwise stiffness distribution with respect to the twist angle at wing tip,the vertical displacement at wing tip,and the flutter speed are obtained using a sensitivity method for both models.Then the relationship between stiffness distribution and aeroelastic performance is summarized to guide the design procedure.By using the genetic/sensitivity-based hybrid algorithm,an optimal solution satisfying the strength,aeroelastic and manufacturing constraints is obtained.It is found that the summarized guidance is well consistent with the optimal solution,thus providing a valuable design advice with efficiency.The study also shows that the aeroelastic-optimization-based global stiffness design procedure can obtain the optimal solution under multiple constraints with high efficiency and precision,thereby having a strong application value in engineering.
基金Supported by the National Natural Science Foundation of China(No.62271400).
文摘In order to get an effective solution of the in-flight wing deformation measurement for high-wing aircrafts with high-aspect-ratio,a method based on three-dimensional(3D)speckle correlation technique is proposed.Firstly,an in-flight wing deformation measurement system with two sets of conjugate cameras is designed based on structural characteristics and test requirements of high-wing aircrafts with large-aspect-ratio.Secondly,the in-flight wing deformation measurement method based on 3D speckle correlation technique is introduced including three aspects:measuring system and wing datum calibration,speckle image matching and 3D reconstruction,and wing deformation analysis.Fi-nally,ground simulation test of dynamic deformation measurement of a scaled model wing and flight test of dynamic deformation measurement of a large transport wing are carried out.The test results show that the measuring accuracy of single point coordinate in ground simulation test is better than 0.1 mm/m,in the airborne vibration environment,the static single-point positioning accuracy is bet-ter than 5 mm,and the in-flight wing deformation measurement data is well received by the flight test engineers.This method can satisfy the requirements of stability,reliability,high precision,non-con-tact and full-field measurement for dynamic deformation measurement of aircraft wing with high-as-pect-ratio.
文摘For the strong coupling among the channels of bank-to-turn （BTT） missile with high-aspect-ratio wing, an autopilot is designed with a two loop control structure robust autopilot design methods. By the inner loop design, the question of pole-zero cancellation is solved, and the stabilization of structured uncertainty is achieved. Through the outer loop of H∞ controller design, the flying performance and robustness can be guaranteed. The nonlinear simulation results show that the autopilot designed has perfect time domain response, and can suppress bad influence of the inertial and kinematics couplings. It can make the missile fly stably in the large flying areas. The control is very effective.
文摘Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.
基金supported by the National Natural Science Foundation of China(Nos.92050202 and 12274299)the Science and Technology Commission of Shanghai Municipality(No.22QA1406600)the Natural Science Foundation of Shanghai(No.20ZR1437600).
文摘High-aspect-ratio structures with heights or depths significantly exceeding their lateral dimensions hold broad application potential across various fields.The production of these structures is challenging,requiring meticulous control over materials,scale,and precision.We introduce an economical and efficient approach for fabricating high-aspect-ratio nanostructures using a two-photon polymerization process.This approach achieves feature sizes of around 37 nm with an aspect ratio of 10:1 using commercial photoresists.Offering advantages over traditional techniques,our approach simplifies operation and enhances design flexibility,facilitating the creation of smaller,more complex,and high-aspect-ratio structures.The capabilities of this approach are demonstrated by producing arrays of three-dimensional microstructures that exhibit sub-micron scales,extensive periodicity,and pronounced aspect ratios.These developments open new possibilities for applications in biomedical,precision engineering,and optical microdevice manufacturing.
基金supported by the National Natural Science Foundation of China(No.92741205)。
文摘Fixed-wing long-endurance aircraft play an important role in many fields.However,to reduce drag,these aircraft often have an enormous aspect ratio and wingspan,leading to challenges such as high requirements for takeoff and landing sites and poor wind resistance.Morphing may be able to solve this problem,but conventional morphing aircraft often employ complex actuation mechanisms and actuators to drive the morphing process.The associated costs in terms of structural weight increase and space occupancy are prohibitively high.First,this article develops a high-aspect-ratio aircraft with aerodynamic-driven morphing and validates the rationality and feasibility of this concept through flight tests.Then,focusing on the RQ-4‘‘Global Hawk”as the design baseline,the article explores multidisciplinary overall design methods for the aircraft,analyzing the comprehensive impact of morphing on aerodynamic,structural,and flight control design.Finally,the article elaborates on the benefits and costs associated with aerodynamic-driven morphing.
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.
