3 Dimensional (3D) Braiding of Non-Uniform Solid Cross Sections

An innovative"4StepPlus"three-dimensional braiding method is proposed for fabricating composite fiber preforms having solid, non-uniform cross sections. The method allows braid unit cells to be individually activated and deactivated after each braiding cycle for applications where changes in part cross section require the addition or removal of yarns. For parts having a cross section that changes in shape while maintaining a similar area, yarns may be moved in any of four directions to simply relocate them to new positions within the integral braid. The ability to incorporate interlocking yarns in two directions enhances the preform's integrity during handling and subsequent processing. Compactness of machinery and high carrier density reduce fiber damage and maintain uniform braid density throughout the part's cross section. The flexible apparatus can be modularly built up in differing complexities, thus keeping costs low. In Phase I, a prototype braider was developed to fabricate prototype fiber preforms demonstrating the ability to change cross-sectional area and shape. In Phase II, we will continue development of our method and machine, and demonstrate fabrication and development of a ceramic-matrix composite fastener with a variable cross section.