ANALYSIS OF A CIRCULAR BRAIDING PROCESS FOR COMPLEX SHAPES

Circular braiders can be adapted to make complex shapes by overbraiding a contoured mandrel and adjusting the process parameters, usually by trial and error. To advance this technology, we developed a detailed model of the braiding process. The model relates the shape of the braid to the machine speeds (which can be profiled), and a number of other machine settings. In addition, the model predicts the local micro-geometry, e.g. orientation angle, yam volume fraction, cover factor, and jamming limits. Experimental results are presented for a number of cases and they confirm the validity of the model. Solutions for special geometries are also presented and some of them yield surprising counter-intuitive results. For example, we found that the direction in which a simple tapered shape is braided has a significant effect on its microstructure. Furthermore, in certain cases, it may be necessary to actually reverse the braiding direction momentarily to achieve a uniform braid.