Development of a 3D Braided Preform for a Rotorcraft Flex-beam

Abstract:
A novel 3-dimensional braiding concept, 4StepPlus, suitable for rotorcraft components where high damage tolerance and fatigue cycles are critical is explored in this paper. 3D textiles such as woven and braided fabrics provide through the thickness reinforcement and thus improved interlaminar strength properties over laminated composites. However, there are challenges in creating shapes with varying cross-sectional shapes and areas. A 4StepPlus 3D braiding approach is used to fabricate a subscale flexbeam with substantial changes in cross-section throughout the length of the part. The mechanical properties of 3D braided composites employing IM7 carbon and S2-glass with RTM epoxy are investigated. The effects of fiber bundle sizes is also assessed as it plays an important role in the performance as well as manufacturing of the component. The results indicate no significant effects of yarn size on the performance of the composites.

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