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Session: Poster session & drinks
Session starts: Tuesday 18 June, 18:00
Presentation starts: 18:02
Room: Room 1.1

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Zexuan Yang (Beihang University/Nanyang Technological University)
Faying Zhang (Beihang University)
Chao Yang (Beihang University)
Bing Feng NG (Nanyang Technological University)
Zhigang Wu (Beihang University)

Abstract:
In order to enable wing morphing (e.g. change in camber or folds) without incurring additional weight to the aircraft, lightweight flexible materials such as membrane is needed. At present, the research on fluid-structure coupling of membranes is mainly focused on airbags and parachutes. However, there is a lack of research on supersonic membrane structures. In this study, a rectangular membrane of length 0.6m and width 0.4m is investigated. A finite element modeling method using shell elements was proposed to study membranes deformation. Establishing a shell model with a very small thickness can approximate a membrane structure due to its low bending stiffness. The method is more effective in solving deformation than using membrane elements directly. Examples are provided to verify the effectiveness of the proposed methodology. Moving a step further, in order to capture aeroelastic effects of the membrane in supersonic flow, a fluid-structure coupling framework was established. It involves an aerodynamic module (involving the piston theory or commercial CFD solvers), a structural module (through ABAQUS) and the coupling is performed through an in-house code developed in Python. Two aerodynamic force solvers are used to analyze the static deformation and dynamic response of the rectangular membrane, and the results are consistent. Subsequently, A parametric analysis is performed on the dynamic pressure and Mach number for their effects on membrane structures. A theoretical analysis is also conducted on a specific phenomenon where the membrane structure vibrates randomly at small angles of attack, but deformation amplitude converges to a common value at large angles of attack. Finally, considering the fact that membrane structure is relaxed, a model with initial relaxation was designed. The results prove that the initial relaxation has a great influence on the deformation, and the influence of various shape relaxations on the results are discussed. Research highlights are as follows: 1. A finite element modeling method using shell elements to simulate membrane structures was proposed. 2. A general framework for fluid-structure coupling of flexible structures in supersonic flow was established, and the aerodynamic force can be solved by piston theory or Fluent. 3. The dynamic response of membrane structure has two forms, the vibration is random at small AoA, and the deformation amplitude tends to converge to a common value at large AoA. 4. A membrane structure with initial relaxation was designed, and the effect of the initial relaxation size and form of deformation were analyzed.