Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves and insect wings,which enhance the hydrophobicity of the natural surfaces and play a role of self-cleaning.We presented the ...Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves and insect wings,which enhance the hydrophobicity of the natural surfaces and play a role of self-cleaning.We presented the fabrication technology of a superhydrophobic surface using high energy ion beam.Artificial insect wings that mimic the morphology and the superhydrophobocity of cicada's wings were successfully fabricated using argon and oxygen ion beam treatment on a polytetrafluoroethylene (PTFE)film.The wing structures were supported by carbon/epoxy fibers as artificial flexible veins that were bonded through an autoclave process.The morphology of the fabricated surface bears a strong resemblance to the wing surface of a cicada,with contact angles greater than 160°,which could be sustained for more than two months.展开更多
With the development of aviation industry,civil aviation has become an indispensable part.Our team will take all the structural dimensions,loads and material parameters in the wing beam structure as the specific value...With the development of aviation industry,civil aviation has become an indispensable part.Our team will take all the structural dimensions,loads and material parameters in the wing beam structure as the specific values determined during the structural design to conduct deflection analysis on the wing beam structure of A380 passenger plane.According to the deflection and parameters analyzed,the stress distribution and maximum stress position on the wing beam can be known.Through the analysis of the wing parameters,the finite element analysis of the wing beam,the mesh sensitivity analysis,and the analysis of the wing tip deflection,the relevant safety factors of the aircraft are obtained.The results show that the wing of airbus A380 is more reliable and safer through the calculation of deflection,stress and safety factor.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
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology(2009-0083068 and 2009-0082607)
文摘Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves and insect wings,which enhance the hydrophobicity of the natural surfaces and play a role of self-cleaning.We presented the fabrication technology of a superhydrophobic surface using high energy ion beam.Artificial insect wings that mimic the morphology and the superhydrophobocity of cicada's wings were successfully fabricated using argon and oxygen ion beam treatment on a polytetrafluoroethylene (PTFE)film.The wing structures were supported by carbon/epoxy fibers as artificial flexible veins that were bonded through an autoclave process.The morphology of the fabricated surface bears a strong resemblance to the wing surface of a cicada,with contact angles greater than 160°,which could be sustained for more than two months.
基金This paper was supported by Educational Reform Project of Zijin College,Nanjing University of Science and Technology(No.20200101002)。
文摘With the development of aviation industry,civil aviation has become an indispensable part.Our team will take all the structural dimensions,loads and material parameters in the wing beam structure as the specific values determined during the structural design to conduct deflection analysis on the wing beam structure of A380 passenger plane.According to the deflection and parameters analyzed,the stress distribution and maximum stress position on the wing beam can be known.Through the analysis of the wing parameters,the finite element analysis of the wing beam,the mesh sensitivity analysis,and the analysis of the wing tip deflection,the relevant safety factors of the aircraft are obtained.The results show that the wing of airbus A380 is more reliable and safer through the calculation of deflection,stress and safety factor.
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.
