In order to investigate the influence of the stitching process parameters on the interlaminar properties of large-thickness stitched composites

this paper prepared stitched composite specimens using a modified locking stitching technique combined with a vacuum-assisted resin infusion (VARI) molding process. The effects of the stitching spacing and prefabricated delamination position on the interlaminar tensile properties were tested using a universal material testing machine. The specimens were characterized by scanning electron microscopy (SEM) to determine the cross-sectional morphology after failure. The results showed that the interlaminar tensile properties of the specimens were best when the stitching spacing was 5mm×5mm and the prefabricated delamination position was at the depth of 17.5mm. The interlaminar fracture mode of the stitched composites was mainly presented as: fracture of the stitches after extraction from the matrix

direct fracture of the stitches within the matrix

and direct fracture of the stitches between the layers.