关键词: 热环境, 壁板结构, 热屈曲临界温度, 固有振动频率, 固有振型

Abstract:

Hypersonic vehicles are exposed to a severe combination of aerodynamic, thermal and acoustic environments during cruise or re-entry flights, which presents a significant challenge for the integrity and the durability of thermal protection systems of aerospace vehicles. Dynamic properties of structures are the basis of dynamic response analysis and optimum design. Thermal dynamic properties of typical stiffened titanium panels with simply supported condition for aerospace vehicles are analyzed in this paper. A finite element model of panels is created using the software NASTRAN. The critical thermal buckling temperature of panels is solved using theoretical and finite element methods. Moreover, natural vibration frequencies and shapes which change with the increase of panel temperature are researched. Modal parameters of panel structures are compared between uniform and nonuniform temperature fileds. Results show that the thermal buckling of panel structures occurs easily in a thermal environment. Therefore, the thermal buckling and large deformation should be considered in thermal modal analysis. It is concluded that the thermal environment has an important effect on the dynamical properties of aerospace vehicle panel structures. The natural vibration frequencies of the panel structures will decrease with the reduction of elastic modulus in the thermal environment. Thermal stresses have many effects both on natural vibration frequencies and on natural vibration shapes. When temperature distribution is changed, the variations of natural vibration frequencies are approximately the same, but the variations of natural vibration shapes are different.

Key words: thermal environment, panel structure, critical thermal buckling temperature, natural vibration frequency, natural vibration shape