Axial impact compressive behaviors of a novel 3-D integrated multilayer fabric reinforced composite tubular structures

Axial impact compression often leads to delamination in laminated composite tubes. A novel 3D fully integrated multilayer tubular fabric invented by authors can eliminate the delamination. This fabric is in tubular form with several layers of crimp-free in-layer yarns oriented at prescribed orientations, fully interlocked by a set of through-layers yarns, which often are made of the same type of fibers as the in-layer yarns. We investigated axial impact compressive behaviors of carbon/epoxy composite circular tubes with reinforcement of the 3D integrated multilayer tubular fabrics. Four different levels of impact energies, i.e., 20 J, 30 J, 40 J and 50 J, were set in tests. The load-displacement curves have been obtained and the damage morphologies have been photographed. The tested results were compared with those in finite element analyses (FEA) with a microstructure model. The tubes were in bulging deformation, resin crack and yarn breakage. We found that the selection of winding yarn is more important to improve axial compressive strength. For the tube designing, the high strength polymer fibers such as polyester fibers could be used for the winding yarns. While high stiffness and strength fibers, such as carbon fibers, must be used for the axial yarns.