Experimental analysis on micro-structure of three-dimensional full five-directional braided composites

Abstract

The micro-structure of three-dimensional( 3D) full five-directional braided composite is investigated. Three-dimensional full five-directional braided composite is a new kind of braided composite. The micro-structure plays an important role in predicting performance of the material. Micro-computed tomography( micro-CT) is used to get the cross-section images of the three-dimensional full five-directional braided composites. Glass fiber as tracer yarns is mixed into the sample made of carbon fiber to improve its contrast in the images. The solid model of tracer yarns created by 3D reconstruction with these images is used to study the cross-sections and orientations of the fiber tows through CAD technology. The results show that the crosssections of braiding yarns and axial yarns change with the regions and the heights in one pitch of the material;the spatial orientations of braiding yarns are not the same in different regions. The axial yarns are almost straightened in space. The surface of the axial yarns has helical indentation because of the extrusion of braiding yarns on axial yarns.