Shearing Properties Of3D Braided Composites With And Without Open-Holes

Three-dimensional braided composites are widely used in the military field, aerospace industry due to their internal structure where continuous carbon fiber bundles run through in four directions, which is definitely different with2D composite. Test and analysis for3D braided composites are keys to use them, while the shearing properties are the focus of engineers’attention. But there is little research of shearing properties of3D braided composites. Bolt or rivet connection is usually used in composites for connecting with other components. Research of composites with mechanical drilling holes is very important. This paper is mainly about shearing properties of3D braided composites with and without drilling holes.Shearing properties of3D braided composites with and without drilling holes were researched. Based on the section of3D braided composites, the damage mode was researched. The result revealed that both for3D braided composites with and without drilling holes, the lateral surface fracture, which was controlled to a small scale, distributed along the path of yarns near the loading point under the short beam load, bending failure occurred on the top and the bottom, no shearing failure occurred in the internal surface2mm and4mm away from the lateral surface except the top and the bottom. The research showed that mechanical opening hardly had extended damage to the3D braided composites, that is, the damage of shearing and drilling is controlled well on3D braided composites.Shearing strength of3D braided composites with and without drilling holes was tested. The results revealed that five-directional composites were better than four-directional composites; the shearing strength increased as the braided angel decreased; the shearing strength of3D braided composites with drilling holes, which diameter is33.3%of the sample width, kept a small range floating of33.3%, and the reduction of3D five directional composite was smaller than that of3D four directional composite. The research also showed that the3D braided composites had great advantage of shearing properties and mechanical opening damage assistant.