三维五向编织复合材料纤维束真实形态观测

Observation on the real shape of fiber bundles in three-dimensional five-directional braided composites

为了对三维五向编织复合材料细观纤维束的真实形态进行描述,采用显微计算机断层扫描技术(Micro-CT)获得三维五向编织复合材料的内部结构切片图像。通过调节灰度差值保留复合材料中纤维束的真实挤压形态,进而利用多层截面堆积的方式提取纤维束的真实形态。在此基础上,利用图像处理技术成功提取纤维束的横截面形状,建立坐标系,计算每一个截面的面积、截面中心点位置、截面偏转角度等纤维束参数,并对其进行分析。结果表明:纤维束在空间中表面存在螺旋状纹路,不同位置的截面变形情况也会不同;编织纱截面形状为凸透镜形,在编织过程中截面形状基本不变;轴纱截面形状呈三角形和扇形过渡变化,在2h/8和6h/8处截面面积最大,4h/8处面积最小;编织纱截面积大小随着花节高度增加呈近正弦式变化,在4h/8处截面积最小,截面偏转角度也最小。研究结果可为后期建立精细化三维五向编织复合材料模型奠定基础。

In order to describe the real shape of microfiber bundles in three-dimensional five-directional braided composites,the internal structure slice image of the three-dimensional five-directional braided composites was obtained by the micro computer tomography(Micro-CT),and the fiber bundles in the composite material were retained by adjusting the difference value of the gray scale.The real shape of the fiber bundles was improved by real extrusion,and the real shape of the multiple fiber bundles was extracted by the accumulation of multi-layer sections.The cross section shape of the fiber bundle was extracted by the image processing technology.The area of each section,the center point position of the cross section and the deflection angle were calculated by the coordinate system.The test results show that there is a spiral pattern on the surface of the fiber bundle in the space,and the deformation of the cross section is also different.The cross section shape of the braiding yarn is convex,and the shape of the cross section is basically the same in the process of braiding;the shape of the axial yarn changes in triangle and fan-shaped transition,and the cross-section area is the largest at 2h/8 and 6h/8 and the smallest at 4h/8.The cross-sectional area of braided yarns varies sinusoidal with the increase of flower node height,and the cross-sectional area at 4h/8 is the smallest and the section deflection angle is the smallest.The research results can lay a foundation for establishing a fine model of three-dimensional five-directional braided composites.