SiC/SiC陶瓷基点阵复合材料夹芯结构的力学性能研究

Lattice sandwich structure is a kind of advanced material which has been given priority in the world due to its light weight and multi-function characteristics. Ceramic lattice sandwich structure is the advance material for future hypersonic vehicle because of its light weight, high temperature resistance and oxidation resistance. Different from the traditional lattice structure, the lattice structure of ceramics is complex and its fracture is probabilistic. How to establish a ceramic matrix lattice structure analysis method considering random effects has become an urgent research topic in this field. In this study, the theoretical analysis model of ceramic matrix sandwich structure is established based on the stress-strength interference theory and Monte Carlo method and the effects of strength probability density function and stress field on its mechanical properties are emphatically studied. Moreover, this project explores the organic integration of 3D printing technology and PIP technology, and proposes a new method to fabricate high-precision SiC/SiC ceramic matrix composite sandwich structure in order to solve the difficult problem of traditional process and high cost. The mechanical experiments of ceramic-based lattice composite sandwich structure under typical load are carried out. Base on the experiments result, the failure mode and failure mechanism of the structure are analyzed and the failure criterion of ceramic-based lattice composite sandwich structure is proposed. The research results provide an exploratory method for the characterization and strength prediction of lightweight ceramic lattice structures, as well as theoretical basis and technical reserves for the design and application of new generation spacecraft structures.

点阵夹芯结构具有轻质和多功能特性，是当前国际上优先发展的一种先进材料。陶瓷点阵夹芯结构在满足轻质的前提下，还具备耐高温、抗氧化等特性，是未来高超声速飞行器的首选材料。陶瓷点阵断裂呈现出概率性，如何建立考虑随机效应的陶瓷点阵夹芯结构的分析方法已成为当前该领域亟需开展的研究课题。本项目基于应力-强度干涉理论和蒙特卡洛法，建立陶瓷点阵夹芯结构的理论分析模型，研究强度概率密度函数和应力场对其力学性能的影响。探究将3D打印技术与PIP工艺进行有机的融合，提出制备高精度陶瓷基点阵复合材料夹层结构的新方法，以解决复杂形状的陶瓷基复合材料结构难于加工和制造成本高的难题。开展陶瓷基点阵复合材料夹芯结构典型力学实验，分析结构的失效模式和失效机理，提出陶瓷基点阵复合材料夹芯结构的失效准则。研究成果为陶瓷点阵结构力学行为的表征提供一种探索性的方法，同时也为新一代航天飞行器结构的设计和应用提供理论基础和技术储备。

本项目在陶瓷点阵夹芯结构的制备工艺、理论分析、数值模拟等方面取得了创新性成果，对超高速飞行器的工程应用具有重要的意义。主要表现在以下几方面：.1.针对陶瓷基复合材料结构难于加工和制造成本高的难题，提出了将3D打印技术与PIP工艺进行有机的融合制备工艺，成功实现了高精度陶瓷点阵夹芯结构的快速制备。.2.提出了陶瓷点阵夹芯结构的理论分析模型，基于陶瓷点阵夹芯结构的应力场和材料最弱链环理论，通过Weibull函数建立了陶瓷点阵夹芯结构可靠性的理论分析模型。.3.基于Python语言和布尔运算，采用舍选抽样法在Weibull分布函数中对材料属性随机取样并赋予不同单元，实现陶瓷点阵夹芯结构数值模型的建立。.4.基于材料静态等效理论，提出了陶瓷点阵夹芯结构的均匀化理论分析模型，推导了其受迫振动的精确解析解。.上述研究成果已发表SCI论文3篇，实现成果转化1项，培养硕士研究生7名，参加学术会议3次。