Braiding procedure and axial compressive behaviors of three-dimensional integrated braided composite three-way circular tubes

The three-dimensional braided composite multi-way tube is one kind of high strength joint with a unique seamless braided microstructure. Here we report a new method to prepare the three-way integrated braided preform. Quasi-static axial compressive damages and strengths of the three-way braided composite tubes were tested for revealing the effects of braided structure on the compressive behaviors. We have paid more attention to braiding yarn strain distribution at the connection region and have found the braided yarns are in a uniform braided structure in this region. Compressive strength and initial stiffness can be improved by reducing branch length or increasing braiding layers. The surface strain on the branch tube shows obvious periodicity related to the braided structure while that on the connection region is affected by the bulging movement due to the compression of the three branch tubes. The main damage mechanisms are yarn breakage, yarn debonding, and kink band. This uniform braided structure paves the way to form the seamless braided structure among three branch tubes with high compressive strength.