针对高超声速飞行器在服役中的高温和高声强环境,分别从高温引起的结构附加热应力和材料物性改变出发,以X-43A为研究对象,使用混合有限元-统计能量分析(FE-SEA)法对其在高温环境、165 dB声压作用下的声振特性进行数值分析。建立由结构FE模型和内声场SEA模型构成的混合声振系统,得到1 800 Hz宽频范围内结构表面响应,并对其能量在空间和频域内的分布进行分析。结果表明:自由状态下,热应力对结构的模态频率影响较小;频域内速度响应曲线与室温相比具有相同的变化趋势,均方根(RMS)值以及多数频段内的功率谱密度(PSD)值略有下降。材料物性改变明显降低了结构的模态频率,响应峰值向较低频率处移动;在结构中部,物性改变引起结构速度响应RMS值的增大及若干频段能量的增加;在前端,物性变化引起结构速度响应RMS值的减小。

This paper presents a numerical study which investigates the effect of high temperature on the dynamic response of a vibro-acoustic system excited by 165 dB acoustic pressure based on a hybrid finite element-statistical energy analysis (FE-SEA) in 1 800 Hz broadband frequency. The study takes into consideration the thermal stress and temperature-dependent material properties mainly through which the thermal environment influences the dynamic response. The coupled system is composed of an FE model of X-43A and an SEA model of its internal acoustic field. The energy response distribution at the top-surface in the space and frequency domain are obtained, which reveals that the thermal stress has only slight effect on the natural frequencies due to the unconstrained structure condition. The velocity response has a similar trend as that in room-temperature, with a small decrease of root mean square (RMS) and power spectral density (PSD) in most bands. Changes in material property reduce obviously the natural frequencies of the structure, and shift the response peaks to lower frequencies. For the central part of the structure, the material property exerts an increasing effect on the RMS value and energy at several bands, while for the forepart the material property has a decreasing effect on the RMS value.