Airframe Structure Of Thermal Vibration Analysis

The aerothermoelastic analysis of missile structure includes the thermal stiffness, thermal vibration and thermal flutter analysis. This dissertation emphasizes on thermal vibration analysis of the aerial vehicle under aerodynamic heat condition.In this paper, some methods are developed to solve the relative problems on thermal vibration of the elastic structure. Firstly, the finite element method is used to analyze the temperature filed and thermal stress, and discuss the three-dimension thermal conductivity mode. The temperature effect which has been calculated is taken as 'thermal load' forced on the body, then such thermal stress is settled as general elasticity mechanics question; Secondly, the thermal stress is taken as 'surface force' forced on the body, and the new system stiffness is formed which include the extra stiffness matrix, then it changes the nature frequency of the structure. Thirdly, this dissertation briefly introduces the engineering estimation method of the aerodynamic heat and supplies the simplified formulas. Not considering the rejection, the ablation and some other factors, the author calculates the stagnation heat flux and the non-stagnation field heat flux distribution of some fly situation as the example aerodynamic heat environment. Finally, by using the ANSYS program, the thermal vibration characters of the plate and missile body structures with different materials is analyzed. The conclusions obtained as follows: firstly, the structure's free frequency is decreased by the reduction of the mechanical property of the material with the increasing temperature; secondly the thermal stress produced by the temperature gradient may decrease or enlarge the structures natural frequency; thirdly, the variety of natural frequency of the alloy structures effected by the heat effect apparently higher than that of the composite material structures.