基于能量法的三维四向编织复合材料细观建模

基于三维四向编织携纱器运动规律和内部纤维束受力分析,提出一种基于能量法的细观建模方法,将建模过程分解为纤维束打紧后控制点的调整、纤维束相互挤压缠绕空间位置的改变和应变能最小时纤维束轨迹的确定.通过单胞模型几何尺寸分析,建立了单胞模型与编织参数之间的对应关系.该建模方法得到的纤维束模型互不干涉且紧密压实,纤维束轨迹为空间曲线与其两条相切直线组成,轨迹接近直线.通过实验对比,纤维束轨迹、模型横截面图与电镜扫描得到的图像一致,计算得到的编织结构尺寸与实验测得数据吻合.花节长度最大计算相对误差在5%左右,特别是编织角在21°左右时,计算相对误差在2%以下.

Mesoscopic modeling of three-dimensional four-directional braided composites using energy method

Based on the motion rules of three-dimensional four-directional braiding yarn carriers and the interior fiber bundle's force analysis, a mesoscopic modeling approach using energy method was established, which divided the modeling process as follows: adjusting the control point after jamming of fiber bundle, changing the position of fiber bundle due to extrusion and interwinding to each other and establishing the fiber bundle trajectory according to the minimum strain energy. By analyzing the geometric dimension of unit cell model, the relationship between unit cell model and braided parameters was provided. The fiber bundle model established by this approach was not interfered but compacted, and the fiber bundle trajectory, composed of a space curve and two tangent lines, was almost a straight line. Compared with the experiment result, the fiber bundle trajectory and cross section of model are consistent with the electron microscope scan images, and braided structure size calculated is in agreement with the measured data. The maximum relative calculation error of pitch length is about 5%, especially when braided angle is 21 degree or so, the relative calculation error is below 2%.