Research on the dynamic and acoustic responses of flat plates in thermal environments is significant to the optimal design of hypersonic aircrafts. For laboratory tests, the high-temperature traveling-wave tube is usually employed to simulate the thermal and acoustic environment to investigate the thermal-acoustic responses of high-temperature structures. In this paper, the thermal-acoustic responses of high-temperature plates in traveling-wave tubes are studied. Based on thin-plate theory and finite element method, the influences of high temperature on the inherent characteristics of flat plates are investigated. The dynamic responses of a simply supported heated C/SiC plates under random acoustic excitation are calculated and analyzed. First of all, the influence of thermal effect on the intrinsic modal characteristics of the flat plate is analyzed. Then, the acoustic load of a one-dimensional traveling wave is added on the surface of the plate. Finally, the analytical method is used to solve dynamic response of the plate under the thermal-acoustic combined loading. The results show that in the heating process, the intrinsic frequency of the plate decreases initially to a minimum value and then increases gradually. In the stage of intrinsic frequency decreasing, the softening effect due to elastic modulus reduction and thermal stresses is stronger than the hardening effect due to the thermal deformation. While in the stage of the intrinsic frequency re-increasing, the hardening effect due to the thermal deformation is dominant. In the range of linear response, the acceleration response of the plate to the thermal-acoustic combined loading depends on its thermal modes.%研究热噪声复合载荷作用下结构的动力学响应对高超声速飞行器结构的设计具有重要的指导意义,实验室多采用高温行波管进行热噪声复合试验研究,本文针对行波管中高温平板结构动力学响应预示方法进行研究.选取四边固支C/SiC材料平板为研究对象,首先研究热效应对平板结构固有模态特性的影响,然后在平板表面施加一维行波声载荷模拟行波管中声场,利用解析方法求解结构在热噪声复合载荷下的动力学响应.结果表明,在加热过程中平板固有频率先减小至极小值,而后逐渐回升.在固有频率下降阶段,材料弹性模量减小和热应力对于结构刚度的软化效应强于热变形的硬化效应;在固有频率回升阶段,热变形的硬化效用起决定性作用.线性响应范围内,平板在热噪声复合载荷下的加速度响应特性取决于其热模态.
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