A novel braiding method and impact behaviors of 3-D braided composite three-way integrated circular tubes

3-D braided composite three-way circular tubes are integrated seamless connected tubes used for high strength connecting joints. We developed a novel braiding method of 'yarn-added, yarn realigned' to prepare three-way tubular preforms. Low-velocity impact compressions (LVIC) along axial direction were conducted to find effects of branch length and braiding layers on impact damage with drop-weight tester, high-speed camera, Micro-CT and digital image correlation (DIC). It was found that the three-way braided tubes have uniform structure both at the branches and joint regions. There is shear band induced by the weakened interface appeared after the peak load and formed within 60 mu s under impact. The ultimate strength was positively correlated with the impact energy and braiding layers, while negatively correlated with the branch tube length. The test results showed that the branch length affected the position of stress concentration, and the influence of braiding layers on the LVIC behaviors is more significant than that of the branch length.

Automated summary

3-D braided composite three-way circular tubes are seamless connected tubes used for high strength connecting joints. A novel braiding method of 'yarn-added, yarn realigned' was developed to prepare three-way tubular preforms. Low-velocity impact compressions (LVIC) were conducted to study the impact damage effect of branch length and braiding layers. The test results showed that the ultimate strength was positively correlated with the impact energy and braiding layers, while negatively correlated with the branch tube length. The influence of braiding layers on the LVIC behaviors is more significant than that of the branch length.