3 Dimensional Nano-Scale Reinforcement Architecture for Advanced Composite Structures

Three-dimensional woven and braided fiber architectures provide important advantages to composites, including suppression of delamination, high damage tolerance, improved through-the-thickness properties, simplicity and cost-effectiveness of manufacturing complex composite structural components. However, in order to diversify applications and reach high volumes of utilization of these materials in high-performance composite structures, such problems as relatively low (compared to tape laminates) fiber volume fraction, reduced in-plane stiffness and strength characteristics have to be resolved. A novel approach to designing and manufacturing 3-D woven and 3-D braided preforms for advanced polymeric and high temperature composites proposed here. The approach is based on the use of very small diameter, ultra-strong and ultra-tough continuous carbon nanotube fibers (developed and produced by the Research Institution of this proposal) as part of the multidirectional reinforcement architecture. Specifically, this kind of fibers will be used as Z-reinforcement in 3-D woven preforms to maximize volume fraction of warp and fill fibers, and as braided tows in special 3-D braided architectures to maximize volume fraction of axial fiber. Finally, it is proposed that carbon nanotube fibers will be selectively integrated into regular, `host' tows to increase local strength, fracture toughness in the zones of anticipated high stress concentration.