| 초록 |
At high speeds of spacecrafts in atmosphere, skin panels may experience severe structural problems such as thermal post-buckling, flutter etc. Functionally Graded Materials (FGMs) have been developed with continuous change from metal to ceramic. FGMs possess excellent high thermal resistance and fracture toughness as compared with metal, ceramic and composite material. In this study, thermal post-buckling and flutter boundaries of functionally graded (FG) panels in hypersonic airflows are investigated. The volume fraction and the material properties of FGMs are gradually changed from metal to ceramic in the thickness direction agreeably to a simple power law distribution and a linear rule of mixture respectively. The material properties of the panels are dependent on the temperature in high temperature environments. The governing equations are derived by using the principle of virtual work and solved by using the finite element method. The panels based on the first-order shear deformation theory (FSDT) are modeled by the von Karman strain-displacement relation and the third-order piston theory is employed to consider the aerodynamic nonlinearity. The Newton-Raphson iteration method is used to solve the nonlinear equation of motions. Flutter boundaries are obtained by linear flutter analysis. The effects of volume fraction, aerodynamic pressure, boundary conditions and temperature change on thermal post-buckling and flutter boundaries are studied. |
