Study On The Key Technology Of Circular Braiding Machine Used 2D Multi-Layer Knitted

2D braided composites have been widely used in aeronautics and astronautics, transportation and so on, because of its excellent integrated properties. The novel preform structure of tubular braided composites has not been reported, which use 2D multi-layer circular tubular knitting technology.Multi-layer 2D tubular synchronous suture technique, a novel knitting method which based on the single-layer 2D tubular knitting process, has been proposed in the paper. The multiple single-layer 2D tubular braided arrays were arranged concentrically, their array numbers are equivalent. A group of radial synchronous suture yarn was added in this braiding process. The fabric could be sutured between layers while used multi-layer 2D tubular knitting process.The carriers'driving mechanism, which was used in 2D multi-layer tubular braiding machine, was designed and analyzed in these works. The 3D model of the main components of the machine was established. The rationalization of the mechanism was validated through carriers'motion simulation.The method of position automatic correction of radial carriers was studied, which resolved the problem of cooperatively movement between circumferential carriers and radial carriers. The cooperatively movement scheme was also designed. The detection circuit of the machine was designed, according to the condition of yarn broken or exhausted. It provides technical implementation to realize multi-layer 2D tubular synchronous suture braiding process and 2D multi-layer circle braiding machine design.Geometric properties of braiding material has been described using unit-cell methods, according to distribution and morphology of unit-cell of 2D tubular multi-layer fabric, symmetry of the braided structure and repeatability of the unit-cell. The relationship has been established between geometry characteristics of the fabric and the braiding parameters. The fiber volume percentage of the braided composites was predicted. And compared with experimental results, verified the establishment of a simplified geometric unit cell model is reasonable. These works are technical conditions for subsequent research in the future.