Low Cost Fabrication Techniques for Propulsion Structures

Cylindrical composite structures are often manufactured by winding, because of its ability to produce large parts at a low tooling cost. Fibers are wound in adjacent bands or in a repeated pattern until the surface is covered. However, winding cannot directly incorporate longitudinal (0º) fibers, except by introduction of an extra step. For geometries with surface features, this is difficult. Without axial reinforcement, wound parts have limited applications where hoop stress is the predominate load (pressure vessels) A technique to address these issues is braiding. Braiding is an automated fiber placement process where multiple fibers are intertwined as they are wound around a mandrel. Tri-axial braiding has longitudinal reinforcement integrated into the layup process which increases the stiffness in the axial direction without the need of an extra step during fiber layup. Braiding can also be used for layups with complicated geometries including those with reverse curvature. The proposed program will investigate braided composites.