复杂载荷下三维角联织物大变形机理研究

Three dimensional (3D) angle-interlock fabrics are widely used in aerospace composite structures due to their advantages of fine structural integrity, high designability and low preparation cost. The deformation molding of 3D fabrics is a key basic problem in the process of composite materials forming. Due to its complex interlacing structure, the mechanism of large deformation of fabric has not been clarified yet. In this project, shear-tension coupling tests and torsion-tension coupling tests combined with digital correlation image testing technology will be used to study the effects of different structures and braiding parameters on the deformation mechanical behavior of fabrics. The pattern of fabric wrinkling is obtained, and the macroscopic deformation characteristics of 3D fabric are illustrated. μ-CT testing technique is going to be used to reconstruct the internal structure of the fabric without deformation and deformation, the morphology, orientation and distribution of yarn are obtained, and the interaction mechanism between yarns is analyzed, revealing the large deformation mechanism of fabric from mesoscale. On this basis, a 3D fabric analysis model is constructed from fiber-yarn-fabric to form a multi-scale analysis method for large deformation of 3D fabric. The critical criterion of wrinkling is formulated. The study of this project will provide the theoretical foundation and design basis for parameters optimization, defect control and performance analysis of 3D angle-interlock fabric composites with complex structures.

三维角联织物因其结构整体性好、可设计性强以及制备成本低等优点而广泛的应用于航空航天复合材料结构件中。三维织物变形成型是复合材料成型过程中的一个关键基础问题，由于其内部交织结构复杂，织物变形机理还未弄清楚。本项目拟采用拉剪和拉扭试验结合数字相关图像测试技术研究不同结构、不同编织参数对织物变形力学行为的影响规律，获取织物的起折模式，阐明三维织物宏观变形特征；利用μ-CT测试技术重构织物未变形和变形状态下的内部结构，获得纱线的形貌、取向以及分布的状态，分析纱线间的相互作用机制，从细观尺度上揭示织物大变形机理；在此基础上，从纤维-纱线-织物构建三维织物数值分析模型，建立三维织物大变形的多尺度分析方法，形成织物起折临界判据。通过本项目的研究为复杂异形结构三维织物复合材料工艺参数的优化、缺陷控制、性能分析提供理论基础和设计依据。

三维角联织物因其结构整体性好、可设计性强以及制备成本低等优点而应用于航空发动机叶片中。然而，三维角联织物在成型为曲面形状叶片时，会发生剪切、扭转等复杂的变形模式，织物的变形成型性能决定了复合材料的质量。项目通过设计不同结构、不同工艺参数的织物试样。在此基础上，设计了三维角联织物的试验工装，形成了织物剪切性能和扭转性能测试方法；利用μ-CT测试技术研究了三维角联织物变形前后的细观结构变化，揭示了织物在不同载荷作用下的变形机理；根据织物的宏细观变形特征，建立了织物变形本构理论；并利用数值仿真方法，模拟了织物的宏细观变形过程，结合试验结果，分析了织物变形过程中纱线的相互作用机制；基于织物的细观变形特征，形成了织物起皱失效判断理论。通过项目研究为复杂异形结构三维织物复合材料工艺参数的优化、缺陷控制、性能分析提供理论基础和设计依据。通过项目实施，已发表了高水平期刊论文12篇(其中SCI共10篇)；申请发表专利2项，授权1项；获得中国纺织工业联合会科技进步奖1项。项目研究结果已在某型号航空发动机叶片的设计及制备中得到应用，并且通过了应用单位的试验考核验证。