热环境对FGM壳模态频率的影响

为了推动功能梯度材料(FGM)在高超音速飞行器热防护结构设计中的应用,旨在探讨不同温度场对热防护壳模态频率的影响,提供热防护壳动力学设计参考。从陶瓷金属基FGM的热物性参数模型入手,结合圆柱薄壳能量原理,建立FGM圆柱壳的模态方程。在此基础上,首先分析热物性参数变化规律对FGM壳模态频率的影响,然后探讨考虑热应力后不同热环境下FGM壳模态频率的变化规律。结果表明,FGM物性参数变化对模态频率的影响没有热力耦合影响明显;温度梯度300 K时,物性参数变化对模态频率起主导作用,反之温度梯度300 K时,热应力和热变形对模态频率起主导作用。

Impacts of thermal environment on modal frequency of FGM shells

In order to promote the application of functionally graded materials (FGMs) in the structure of thermal protection systems,the aim of this work is to study the impacts of different temperature fields on the modal frequencies of thermal protection shells and to provide some methods for dynamical design of hypersonic aircrafts. Starting from the thermal-physical property model of the ceramic and metal based FGMs,the modal frequency equation of an FGM shell was derived by using the energy principle. Thereafter,the impacts of the change law of thermal physical properties on modal frequencies were analyzed. And the change law of modal frequency of the FGM shell with thermal stress was discussed under different thermal conditions. Results indicate that the impacts of the change of physical properties on the modal frequency are less than that of thermal-mechanic coupling on the modal frequency. The change law of physical properties plays a main role on modal frequency when the temperature grade below 300 K while the thermal stress and strain plays a main role when the temperature grade above 300 K.