三维编织复合材料细观结构建模关键问题研究

A study of key issues in modeling the microstructure of 3D woven composites

基于细观力学的数值分析方法是研究三维编织复合材料力学性能的有效方法,其中细观模型的建立是力学分析的基础。纤维束的空间走向和细观结构几何参数表征是细观结构建模中的两个关键问题。围绕这两个关键问题,针对三维四向编织复合材料的三单胞模型开展研究,全面分析了单胞45°划分方式和水平划分方式中纤维束的各种空间走向,获得了详细的三单胞的纤维束方向余弦;针对三种形状的纤维束横截面,分析推导了编织工艺参数与单胞几何参数的复杂关系,利用编织工艺参数作为初始参数对单胞结构进行定量化表征,并获得了纤维束体积分数和纱线填充系数的计算方法。研究工作为三维多向编织复合材料的细观结构建模提供理论参考,具有一定的工程实用价值。

Numerical analysis based on micromechanics is an effective method to study the mechanical properties of three-dimensional(3D)braided composites,in which the establishment of micromechanics model is the basis of mechanical analysis.The direction cosine of fiber yarns and the characterization of geometric parameters of microstructure are two key issues in the modeling of microstructure.Focusing on these two key issues,the three-cell model of 3D four-directional braided composites is studied to analyze various spatial directions of fiber yarns in the 45°division and horizontal division of unit cell,so as to obtain the detailed fiber yarn direction cosine.Aiming at the cross sections of three types of fiber yarns,the complex relationship between the braiding process parameters and the geometric parameters of the unit cell is analyzed and deduced.The unit cell structure is quantitatively characterized by using the braiding process parameters as the initial parameters,and the calculation methods of the volume fraction of fiber yarns and yarn filling coefficient are obtained.This paper can provide a theoretical reference for the microstructure modeling of 3D multi-directional braided composites,and has certain practical value in engineering.