Vibration and Flutter Analysis of Stiffened Composite Plate Considering Thermal Effect

Vibration and flutter analyses have been performed for stiffened composite laminated plates considering thermal effect. The FSDT (First order Shear Deformable plate Theory) and Timoshenko beam theory are used for the finite element modeling of a skin panel and stiffeners, respectively. The von Karman nonlinear strain-displacement relation is adopted to consider a large deflection due to the thermal buckling loads and severe aerodynamic loads. The first order piston theory is used for the modeling of aerodynamic loads. The temperature distribution is assumed to be constant over the surface and has a thermal gradient through the thickness of the plate. It is assumed that a degradation of the elastic properties of the constituent materials is a function of the temperature field itself. Guyan reduction method is employed to reduce the problem size and computational time. Newton-Rhapson iteration method is used to obtain the postbuckled deflection. Complex eigenvalue solver with LUM/NTF approximation method is used to obtain vibration and flutter characteristics. The effects of various parameters, such as ply orientation, temperature gradient, material property degradation and the stiffening scheme on flutter characteristics are investigated through some numerical examples. The degradation of material properties affects the aero-thermo-postbuckled deflection, vibration characteristics and flutter boundary. The selection of proper stiffening scheme results in great improvements of flutter characteristics of laminated panels without introducing considerable weight penalty.