3D Structural Simulation of Tubular Braided Fabrics for Net-Shape Composites

A circular braiding machine can be used to produce complex shapes by overbraiding a contoured mandrel and adjusting the process parameters. To simplify the design process and advance this technology, a CAD model is developed to describe the geometry of a 3D circular braid both externally and internally. A quadrilateral mesh is used to generate the over-all yarn appearance from a wire-frame model with texturing and light reflection applied to the surface. Comparison with other simulated structures using different models and with real yams shows that the simulated fabric described in this paper is more accurate and yields an improved visual representation of real preforms. The model takes into account the structural characteristics of yams and the finite dimensions of fibers. The effects of yam crimp, weave pattern, and tubular shape on the yarn appearance in the preform are examined. Some applications of the model to net-shape composite designs are presented, such as a canoe paddle, a drive shaft, and a shaped preform.