摘要: Composite materials have several advantages over other materials in lightweight aerospace or automotive applications due to their high specific strength, specific stiffness, tailorability, and corrosion resistance. However, due to... 展开 Composite materials have several advantages over other materials in lightweight aerospace or automotive applications due to their high specific strength, specific stiffness, tailorability, and corrosion resistance. However, due to their low interlaminar tension and shear strengths, delaminations and microcracking severely degrade the overall mechanical response of the composite structure. Through-the-thickness stitching of layered composites can provide the necessary reinforcement in the z-direction that enhances the interlaminar tensile and shear properties while maintaining structural continuity. However, stitching reduces the in-plane properties of composites, which can have serious implications for the application of such composites in different aerospace load-bearing structures. Graphene nanoplatelets (GNPs) and 'thin plies' have been found to be efficient in increasing the mechanical properties of unstitched composites. Therefore, the objective of this study is to investigate the influence of GNPs and embedded thin plies on the tensile properties of three-dimensional stitched composites. Stitched and unstitched carbon fiber preforms (|+45/-45]4s) were infused with an unmodified epoxy resin and used as the baseline. The same epoxy resin was modified by dispersing graphene nanoplatelets (GNPs) and was infused into stitched carbon preforms with and without embedded thin plies at the midplane. Specimens were stitched with two different stitch seam angles (0° and 90°) and the fabricated specimens were tested under uniaxial loading. Digital image correlation was used to obtain the surface strain fields. Significant differences were observed in the strain distributions and tensile properties of stitched specimens with GNP modified epoxy when compared to the baseline. Specimens with the GNP modified resin and embedded thin ply showed the largest increment in the modulus of elasticity with severely reduced strain concentration zones around the stitching sites. 收起