高超声速飞行器因为其具有5马赫以上的飞行速度，结构材料所处的热力学环境极端恶劣，飞行器表层材料长时间处于高温状态、且承受了宽频强噪声激励作用，这种复杂的气动力热载荷环境对高超声速飞行器结构的安全性和可靠性提出了严峻挑战，尤其是当高超声速飞行器追求结构极致轻量化设计目标时，热噪声激励诱发的耦合效应愈加明显。

本文针对高超声速飞行器飞行时面临严酷的热噪声环境，开展飞行器主体结构和轻量化功能结构在高温、强噪声激励下的随机振动动力学响应特性研究，初步建立了基于频域分析方法的热噪声激励结构动力学行为分析方法。结合数值和实验研究获得了热噪声联合作用下结构的动力学响应规律，可望为高超声速飞行器的结构优化提供理论方法和实验技术参考。

本文包含的研究工作进展主要在于：

1. 高超声速飞行器复杂结构的随机振动频域分析方法研究。考虑到噪声载荷是一种具有随机性的动态压力载荷，同时兼有一定的时间和空间分布的特征，基于多自由度系统的离散格式动力学基本方程，推导了高温环境、宽频强噪声共同作用下结构的动力学控制方程。研究进一步验证了对于飞行器结构噪声激励响应，本文仿真模拟所采用的随机振动频域分析方法的可靠性；随后，基于随机振动频域分析方法，开展了高速飞行器主体结构热噪声环境激励动力学响应分析。结合高速飞行器主体结构的模态数值分析和试验测试分析，获得了常温条件飞行器结构固有频率、振型和阻尼比等结构动力学固有属性；然后对高速飞行器主体结构同时施加高温和强噪声载荷，通过有限元数值求解动力学方程，得到高速飞行器主体结构的位移均方根分布和部件结构位移功率谱密度曲线。激励响应结果证实，热噪声环境中高超声速飞行器结构的垂直尾翼部件变形明显，这在飞行器结构动力学行为的后续优化设计中应当得到足够重视。

2. 热防护结构的轻量化设计研究。由于高超声速飞行器结构材料所处的复杂气动力热环境，飞行器结构设计时应综合考虑热防护的要求，本文研究对典型夹芯层轻量化结构在热防护系统中的主动冷却功能实现作了初步探讨。首先建立了多种典型夹芯板的几何模型，采用随机振动频域分析方法对比分析了这些典型轻量化夹层结构在热噪声环境激励的动力学响应，分析结果显示圆柱壳夹层板结构在高超声速飞行器所处的复杂热噪声环境中的力学性能相对而言具有一定的优越性。随后针对圆柱壳夹芯的多层排列结构研究了圆柱壳直径梯度变化的设计布局，通过随机振动频域分析方法对比分析了圆柱壳无梯度板结构、圆柱壳顺梯度板结构和圆柱壳逆梯度板结构在热噪声环境下的动力学响应，结果证实圆柱壳逆梯度结构可以更好的发挥圆柱壳夹层板的优势。

3. 典型轻量化夹层结构在热噪声环境下响应规律分析。本文首先研究实现了圆柱壳夹层板结构的模态试验方法，并结合试验结果和有限元模态分析结果，获得了单层圆柱壳夹层板结构的固有频率、振型和阻尼比等结构动力学固有属性。然后，针对环境温度的变化，开展了圆柱壳夹层板结构的热模态分析，计算结果证实了结构的固有频率随着温度升高而下降的明显趋势。针对不同幅值/强度的热噪声激励，开展了热噪声共同作用下圆柱壳夹层板结构的动力学响应规律研究。通过分析结构危险点的横向位移功率谱密度分布结果发现：环境温度给定时，结构动力学响应峰值位置对应的频率即已确定，峰值幅值主要取决于噪声强度；噪声强度给定时，温度水平将同时决定结构动力学响应峰值和峰值位置对应的频率。最后，本文尝试建立了声激励结构响应试验系统，试验分析了结构响应对噪声声压级的依赖关系，为后续热噪声联合加载复杂结构试验方法奠定部分基础。

Hypersonic vehicles have a flight speed of more than Mach 5, and the thermodynamic environment of the structural materials is extremely harsh, the surface material of the vehicle is in a high temperature state for a long time, and it is subjected to a wide range of strong noise excitation. This complex aerodynamic thermal loading environment puts forward severe challenges to the safety and reliability of hypersonic vehicle structures, especially as the coupling effects caused by thermal noise excitation become increasingly evident as hypersonic vehicles pursue their ultimate lightweight design goals.

In this paper, the random vibration dynamics response characteristics of the main structure of the vehicle and the lightweight functional structure under high temperature and strong noise excitation are studied for the severe thermal noise environment faced by the hypersonic vehicle in flight, and a preliminary analysis method of the structural dynamics behavior based on frequency domain analysis is established. The dynamical response of the structure under the combined effect of thermal noise is obtained by combining numerical and experimental studies, which is expected to provide theoretical methods and experimental technical references for the structural optimization of hypersonic vehicles.

The progress of research work included in this paper mainly lies in:

1. The study of frequency domain analysis method of random vibration of complex structure of hypersonic vehicle. Considering that the noise load is a kind of dynamic pressure load with randomness and certain characteristics of both time and space distribution, the dynamic control equations of the structure under the joint action of high temperature environment and wide frequency strong noise are derived based on the basic equations of discrete format dynamics of multi-degree-of-freedom system. The study further verifies the reliability of the random vibration frequency domain analysis method used in the simulation for the noise excitation response of the vehicle structure; subsequently, the dynamic response analysis of the thermal noise environment excitation of the main structure of the high-speed vehicle is carried out based on the random vibration frequency domain analysis method. By combining the modal numerical analysis and experimental test analysis of the main structure of the high-speed vehicle, the inherent properties of the structure dynamics such as the inherent frequency, vibration type and damping ratio of the vehicle structure at room temperature are obtained; then the high temperature and strong noise loads are applied to the main structure of the high-speed vehicle at the same time, and the kinetic equations are solved numerically by finite elements to obtain the root mean square distribution of the displacement of the main structure of the high-speed vehicle and the displacement power spectrum density curves of the component structure. The excitation response results confirm that the vertical tail component of the hypersonic vehicle structure deforms significantly in the thermal noise environment, which should be paid sufficient attention in the subsequent optimization design of the vehicle structure dynamics behavior.

2. Research on the lightweight design of thermal protection structure. Due to the complex aerodynamic thermal environment in which the structural materials of hypersonic vehicles are located, the requirements of thermal protection should be considered comprehensively in the design of vehicle structures. In this research, a preliminary discussion of the active cooling function of the typical chip layer in the thermal protection system is realized. Firstly, the geometric models of various typical sandwich panels are established, and the dynamic response of these typical lightweight sandwich structures in the thermal noise environment is compared and analyzed using the random vibration frequency domain analysis method. The analysis results show that the mechanical properties of the complicated thermal noise environment of the cylindrical shell mezzanine structure in the hypersonic flyer have a certain superiority in terms of relative terms. The design layout of the cylindrical shell with varying diameter gradient is then studied for the multilayer arrangement structure of the cylindrical shell sandwich core, and the dynamic response of the cylindrical shell without gradient plate structure, the cylindrical shell with gradient plate structure and the cylindrical shell with inverse gradient plate structure are compared and analyzed by the random vibration frequency domain analysis method in the thermal noise environment, and the results confirm that the cylindrical shell with inverse gradient structure can better exploit the advantages of the cylindrical shell sandwich plate.

3. Analysis of the response law of a typical lightweight sandwich structure under thermal noise environment. In this paper, firstly, the modal test method of the cylindrical shell sandwich panel structure is studied and implemented, and the inherent properties of the structural dynamics such as the inherent frequency, vibration pattern and damping ratio of the single-layer cylindrical shell sandwich panel structure are obtained by combining the test results and the finite element modal analysis results. Then, the thermal modal analysis of the cylindrical shell sandwich panel structure was carried out for the change of ambient temperature, and the calculation results confirmed the obvious trend that the inherent frequency of the structure decreases with the increase of temperature. For the thermal noise excitation of different amplitude/intensity, the study of the dynamic response law of the cylindrical shell sandwich panel structure under the joint action of thermal noise is carried out. By analyzing the results of the transverse displacement power spectrum density distribution of the structural hazard points, it is found that: when the ambient temperature is given, the frequency corresponding to the peak position of the structural dynamic response is determined, and the peak amplitude mainly depends on the noise intensity; when the noise intensity is given, the temperature level will determine both the peak of the structural dynamic response and the frequency corresponding to the peak position. Finally, this paper attempts to establish an acoustically excited structural response test system and analyzes the dependence of the structural response on the noise sound pressure level, laying part of the foundation for the subsequent thermal-noise combined loading test method for complex structures.