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根据三维机织复合材料中细观几何和变形的周期性 ,提出了一种反映细观周期约束条件的组合梁单元模型 ,该模型既考虑了纤维束的偏轴拉压效应 ,又考虑了纤维束的弯 /剪耦合效应和纤维束之间的相互作用 ,可以描述纤维束和基体中的细观应力分布。针对一种典型的三维机织复合材料 ,研究了根据编织参数确定材料细观结构的方法 ,在此基础上选取材料中最小周期的一段纤维束作为分析胞元 ,用上述模型分析了面内拉伸荷载下胞元中各相材料的细观应力 ,进而得到材料平均的宏观模量。材料试验和二维细观有限元分析证明了本模型的可靠性。研究表明 ,三维机织复合材料中 ,纤维束拉、弯耦合效应引起的细观应力在应力分析中不可忽略
According to the mesoscopic geometry and the periodicity of deformation in 3D woven composites, a composite beam element model reflecting the mesoscopic period constraints was proposed. The model not only considered the off-axis tension-compression effect of the fiber bundles, but also considered the fiber Beam shear / shear coupling effects and the interaction between fiber bundles can describe the distribution of mesostructures in fiber bundles and matrices. Aiming at a typical three-dimensional woven composite material, a method of determining the mesostructure of the material according to the weaving parameters was studied. Based on the selected section, a fiber bundle with the smallest period in the material was selected as the analytic unit cell. The above- The mesostructural stresses of the materials in each cell in the cell under load can then be obtained as the average macroscopic modulus of the material. Material testing and two-dimensional mesoscopic finite element analysis demonstrate the reliability of this model. The research shows that in three-dimensional woven composites, the mesoscopic stress caused by the pull-bend coupling effect of fiber bundles can not be neglected in stress analysis