金属点阵夹层板高温热屈曲行为与失效机理研究

Thermal buckling is one of the most important failure mechanisms in the large-scale thermal protection structures for high speed flights. This project aims to reveal the controlling and influencing parameters of thermal buckling behavior (critical temperature, buckling mode and failure mechanism) for sandwich structures with metal truss cores, and three aspects are concerned: the main structure parameters, damage and defects, and complex thermal-mechanical environment. Through systemic experimental approach and analytical method, the controlling mechanisms of macroscopic geometry and mesoscopic topology to the different buckling modes and failure behavior will be revealed, and the influence of fabricated damages and stochastic defects to the critical buckling temperature and buckling modes will be obtained, and the buckling behavior of sandwich panels subjected to non-uniform thermal-mechanical environment such as gradient heating in the through-thickness direction and plane direction will be examined. The study will provide theoretical foundation and experimental data to the thermal buckling design of truss core sandwich panels. Meanwhile, the project also emphasis the development of new experimental method and non-contact measurement technique for high temperature thermal buckling tests. The significances of the project are to propel the application of truss core sandwich in the thermal protection and light-weight structure design of high speed flights, and to promote the application of new thermal-mechanical loading method and full-field measurement technique in thermal-structural tests.

热屈曲是高速飞行器的大面积热防护结构的主要失效形式之一。本项目针对金属点阵夹层板的热屈曲行为（临界温度，屈曲模态和失效机理）的主控与影响因素开展研究，重点考察结构主控参数、损伤与缺陷、复杂热-力环境等三个方面对点阵夹层板热屈曲行为的影响规律。旨在揭示宏观几何尺寸和细观拓扑结构对点阵夹层板形成不同屈曲模式与失效行为的主控机制；获取不同形式的预制损伤和随机缺陷对热屈曲临界载荷与屈曲模态的影响机制；掌握沿厚度及面内方向梯度热加载等非均匀热力环境条件下的热屈曲行为，从而为点阵夹层板的抗热屈曲结构设计提供基础理论和实验数据。同时，本项目还将重点发展高温环境下的热屈曲的实验方法和非接触式全场测量技术。预期的成果有望推动点阵夹层板在高速飞行器热防护结构轻量化设计中的应用；促进新型热力加载方法与全场测量技术在高温环境下热结构测试中的应用。

热屈曲是高速飞行器的大面积热防护结构的主要失效形式之一。本项目通过理论分析获得了不同热力载荷下点阵夹层板热屈曲失效模式与失效机理，分析了宏、细观结构参数与材料参数对点阵夹层板热屈失效行为的影响规律，得到了不同失效模式之间的竞争与转换阈值，形成了高温热力载荷下点阵夹层板失效图谱；制备了含预制面板损伤和芯材损伤点阵夹层板试件，研究了损伤与缺陷的大小、数量和位置对点阵夹层板屈曲行为的影响；开展了面内及沿厚度方向非均匀温升环境下点阵夹层板热屈曲失效行为研究，获得了非均匀热-力环境条件下的结构响应与参数影响分析。通过本项目的研究，获取了结构主控参数、工艺状态和热-力环境对点阵夹层板热屈曲行为和失效机理的影响规律，掌握了高温环境下夹层板热屈曲的实验方法和全场测量技术，为促进点阵夹层板在高速飞行器的工程应用提供了关键的实验数据与理论依据。