Nonlinear Thermal Flutter Analysis Of Two-dimensional Panels In Supersonic Flow

With the emergence of high-speed aerocraft, researchers home and abroad pay close attention to panel thermal flutter issue, which always leads to the fatigue failure of the skin panels and has a harmful influence on the flight performance and even flight safety. Considering the geometrically nonlinear effects of the structure, combined with first-order piston theory, the nonlinear dynamics behavior of the two-dimensional flat and curved panels in supersonic airflow and thermal environment is investigated. The main contents of the thesis are as follows:(1) Based on the Kirchhoff thin plate theory and the von Karman's nonlinear large deformation strain-displacement relations, the dynamic equations of the flat panel are established, where the first-order piston theory is used to calculate the nonlinear aerodynamic load. Then the equations are simplified into dimensionless forms and converted into modal space. In the analysis, only the first two modals of the flat panel are selected. The supercritical Hopf bifurcation point of system is obtained by the algebraic criterion of Hopf bifurcation, then the Normal Form direct method is used to obtain the coefficient of Normal Form at the bifurcation point. The Wash-out-filter technology is introduced to design the controller, in order to control the thermal flutter actively. The theoretical analysis is verified by numerical simulations.(2) The nonlinear flutter analysis of a curved panel with thermal effect is carried out, The aerothermoelastic equations are established by Hamilton's principle, the Galerkin approach is adopted to simplify the equations into discrete forms, then the equations are transformed from physical coordinates into modal coordinates, eventually the four-dimensional one-order differential equations are derived. The numerical simulation is carried out to analyse the effects of various parameters on flutter amplitude values. Using pressure of airflow and initial geometric curvature as bifurcation parameter, the nonlinear dynamic behavior of the panel is studied. The results show that, within different ranges of the bifurcation parameter, the two-dimensional curved panel shows complex nonlinear vibration behavior, such as limit-cycles, period-doubling movements as well as chaotic motions.(3) The flutter behavior of the flat panel and curved panel under the same situations is compared.The researches of the thesis provide a theoretical basis for the cubic nonlinear system, and provide a reference for the nonlinear dynamics study of aircraft panels as well as the anti-shake design.