Experimental characterization of multistitched two-dimensional (2D) woven E-glass/polyester composites under low-velocity impact load

The aim of this study was to understand the low-velocity impact energy absorption mechanism of the developed two-dimensional multistitched multilayer E-glass/polyester-woven composites. It was found that the specific front and back face damaged areas of the two-dimensional multistitched E-glass/polyester-woven composites were smaller than those of the two-dimensional unstitched structures. When the stitching density increases, the front and back face damaged areas generally decrease. In addition, when the number of stitching directions increased, the front and back face damaged areas decreased. Therefore, stitching density, stitching directions, stitching yarn, and stitching type on the composite structures were considered as important parameters. Impact load caused a small indentation in the center of front face and resulted in fiber splitting and fiber breakages in the center of the back face of the structure. On the surrounding area of the front and back face damaged zones of the structures, fiber-matrix debonding and matrix breakages were observed. These results indicated that multistitching suppressed the impact energy to a small area of the composite structure. Thus, the two-dimensional Kevlar®129 or E-glass-multistitched E-glass/polyester-woven composite structures showed better damage tolerance performance compared to the unstitched composite structures.