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Flutter analysis of Aircraft Wing Using Equivalent-Plate Models with Orthogonal Polynomials

Transactions of Nanjing University of Aeronautics and Astronautics 2015年第5期32卷 508-516页

作者：唐健谢长川杨超 School of Aeronautic Science and Engineering Beihang University

A method of equivalent simplification,using equivalent-plate models(EPMs),is developed.It is to achieve goals of rapid modeling and effective analysis in structural dynamics and Flutter analysis of complex wing structures.It is on the assumption that the wing structures discussed are composed of skin,beams and ribs,and the different plate units(such as skin,beam web,rib web)are not distinguished in modeling,which is to avoid the complex pre-processing and make it more generalized.Taking the effect of transverse shear deformation into consideration,the equivalence is based on the first-order shear deformation theory,and it can import the model files of MSC/NASTRAN and process the information to accomplish the equivalent modeling.The Ritz method is applied with the Legendre polynomials,which is used to define the geometry,structure and displacements of the wing.Particularly,the selection of Legendre polynomials as trial functions brings good accuracy to the modeling and can avoid the ill-conditions.This is in contrast to the EPM method based on the classical plate theory.Through vibration and Flutter analysis,the results obtained by using EPM agree well with those obtained by the finite element method,which indicates the accuracy and effectiveness in vibration and Flutter analysis of the EPM method.

关键词： equivalent-plate model(EPM) Flutter analysis vibration analysis Ritz method orthogonal polynomials

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Structural design and modal behaviors analysis of a new swept baffled inflatable wing

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Defence Technology（防务技术） 2023年第6期24卷 382-398页

作者： Nuo Ma Li Liu Fanmin Meng Junhui Meng School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081PR China

Inflatable wing has significant application value in the design of loitering munitions because of its advantages such as lightweight and foldability.However,due to the flexible characteristics,aeroelastic behaviors of inflatable wings such as flutter are nonnegligible in flight.By designing a certain angle between the inflatable beam and the wing span,the structural dynamic and even the aeroelastic performance of the inflatable wing can be effectively improved.Based on the analysis of the mechanical and geometric characteristics of the inflatable structure,a new inflatable wing with sweep arranged inflatable beams is proposed,and the main design variables and methods are analyzed.For purpose of investigating the aeroelastic performance of the swept baffled inflatable wing,the modal behaviors by considering the wet mode are studied.In consideration of the deficiencies of the traditional wet modal analysis method,by introducing the influence on the additional stiffness of flow field,an added massstiffness method is proposed in this paper,and the advantages are verified by ground vibration experiments.On this basis,the effects of baffles sweep angle,pressure,and boundary conditions on the modal parameters and aeroelastic performance of inflatable wing are analyzed.The results show that the aeroelastic performance of the inflatable wing can be designed by changing the baffles sweep angle,which is enlightened for the aeroelastic tailoring design on inflatable wings.

关键词： Inflatable wing Structural design Wet mode Flutter analysis

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A New Smoke Detection Method of Forest Fire Video with Color and flutter

A New Smoke Detection Method of Forest Fire Video with Color...

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2015年中国智能自动化学术会议

作者： Zhong Zhou Ya-qin Zhao College of Mechanical and Electronic Engineering Nanjing Forestry University

Big region area, long distance, and fast motion are the main characteristics of smoke video. Traditional smoke video detection has a high false alarm rate.In order to improve the detection accuracy, we propose a novel method to detect smoke video based on color information and Flutter analysis. The proposed method can effectively exclude the influence of those objects resembling the smoke motion and reduce false detection rate resulting from illumination change and smoke-color objects. In detail, a background updating model of forest fire smoke video is first built using the Kalman filtering method. Combining updating model with the smoke HSV and RGB color space, candidate smoke video region is segmented.Then, three flutter features, including flutter direction of the video smoke, changing rate of the smoke area, and background ambiguity, are extracted by sliding time window analysis of the candidate smoke. Finally, the characteristic values are used to judge whether it is smoke. Experiment results show that our method can detect the video smoke more accurately as well as faster than the state-of-the-art methods.

关键词： Smoke video detection Kalman filtering Color space Flutter analysis Wavelet transform

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